Sire Lines & "Y" They Matter

[acespicoli]

Been interested in this topic for awhile now, maybe some others are as well?
Questions why is cannabis important to us?
Which genes are sex linked ?
What are the current and future implications of culling males and hermaphrodites ?

Is saving only female plants degrading the varieties and whole gene pool ?


Genome Res. 2020 Feb; 30(2): 164–172.
doi: 10.1101/gr.251207.119
PMCID: PMC7050526
PMID: 32033943

An efficient RNA-seq-based segregation analysis identifies​

the sex chromosomes of Cannabis sativa​

[IMG alt="An external file that holds a picture, illustration, etc.
Object name is 164f01.jpg"]https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7050526/bin/164f01.jpg[/IMG]

Figure 1.
Experimental design and bioinformatic pipeline to identify sex-linked genes. (A,B) The SEX-DETector analysis relies on obtaining genotyping data from a cross (parents + F1 progeny). (C) SEX-DETector infers the segregation type based on how alleles are transmitted from parents to offspring. Three segregation types are included: autosomal (alleles of the parents are transmitted to the progeny the same way in both sexes, in a Mendelian way), XY (one allele of the father—the Y allele—is transmitted exclusively to sons), X-hemizygous (the single allele of the father is transmitted exclusively to daughters; the sons get one allele from the mother only). See Methods for more information. C. sativa male and female plants pencil illustration by annarepp/Shutterstock.com.

An efficient RNA-seq-based segregation analysis identifies the sex chromosomes of Cannabis sativa

Cannabis sativa–derived tetrahydrocannabinol (THC) production is increasing very fast worldwide. C. sativa is a dioecious plant with XY Chromosomes, and only females (XX) are useful for THC production. Identifying the sex chromosome sequence would ...

www.ncbi.nlm.nih.gov

[IMG alt="An external file that holds a picture, illustration, etc.
Object name is 164f02.jpg"]https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7050526/bin/164f02.jpg[/IMG]
Figure 2.
Distribution of the sex-linked and sex-biased genes onto the C. sativa reference genome. From outer to inner rings: (1) Chromosomes from 1 to 10 and unassembled scaffolds of the reference genome (Grassa et al. 2018); (2) X-Y dS values (from 0 to 0.4); (3) proportion of XY-linked genes (in blue) and X-hemizygous genes (in red) in 2-Mb windows; (4) proportion of genes with sex-biased expression in 2-Mb windows: male-biased (light blue), female-biased (orange). THCAS and CBDAS genes found in Grassa et al. (2018) are indicated by two red dots near the outer ring.

 

[acespicoli]

https://www.jstage.jst.go.jp/article/cytologia1929/63/4/63_4_459/_pdf

some dioecious flowering species have an active-Y system of sex determination with
heterogametic males (XY) and
denoting the sex which has sex chromosomes that differ in morphology, resulting in two different kinds of gamete,

homogametic females (XX)
denoting the sex which has sex chromosomes that do not differ in morphology, resulting in only one kind of gamete


gam·ete
/ˈɡaˌmēt,ɡəˈmēt/
https://www.google.com/search?sa=X&...2ahUKEwiDwLKJkKyHAxWYMlkFHeRKBy0Q3eEDegQIOBAM
noun
BIOLOGY
noun: gamete; plural noun: gametes

1. a mature haploid male or female germ cell which is able to unite with another of the opposite sex in sexual reproduction to form a zygote.

https://floraflex.com/default/blog/post/understanding-cannabis-polyploidy-exploring-the-effects-of-chromosome-doubling#:~:text=Cannabis%20is%20typically%20diploid%2C%20meaning,be%20induced%20through%20laboratory%20techniques.

Plant genera Cannabis and Humulus share the same pair of well-differentiated sex chromosomes​

Djivan Prentout, Natasa Stajner, Andreja Cerenak, Theo Tricou, Celine Brochier-Armanet, Jernej Jakse, Jos Käfer, Gabriel A. B. Marais
First published: 12 May 2021

https://doi.org/10.1111/nph.17456
.

Molecular Cytogenetic Characterization of the Dioecious Cannabis sativa with an XY Chromosome Sex Determination System - PMC

Hemp (Cannabis sativa L.) was karyotyped using by DAPI/C-banding staining to provide chromosome measurements, and by fluorescence in situ hybridization with probes for 45 rDNA (pTa71), 5S rDNA (pCT4.2), a subtelomeric repeat (CS-1) and the ...

www.ncbi.nlm.nih.gov

.
https://link.springer.com/article/10.1007/s10681-004-4758-7
.

Frontiers | Hermaphroditism in Marijuana (Cannabis sativa L.) Inflorescences – Impact on Floral Morphology, Seed Formation, Progeny Sex Ratios, and Genetic Variation

Cannabis sativa L. (hemp, marijuana) produces male and female inflorescences on different plants (dioecious) and therefore the plants are obligatory out-cros...

www.frontiersin.org

Among the examined populations, natural
triploids were identified in 10 groups with an average frequency of approximately 0.5%. The highest
frequency of natural triploids was observed in a self-pollinated population at 2.3%. This research
demonstrates that polyploidy is a naturally occurring event in cannabis and triploids are present at
an average of approximately 0.5%, or 1 in 200 plants. These data shed light on the natural variation in
ploidy within cannabis populations and contribute valuable insights to the understanding of cannabis
genetics and breeding practices


...


Hermaphroditism carries both advantages and disadvantages.
Perfect flowers can, assuming no other constraints, self-pollinate and fertilize their own ovules. This sexual reproduction without the need for another individual of the same species gives the plant a certain set of advantages.

 

[numberguy]

[only females [xx] are useful for THC production], gov led missinformation at its finest.

 

[CharlesU Farley]

Hermaphroditism carries both advantages and disadvantages.
Perfect flowers can, assuming no other constraints, self-pollinate and fertilize their own ovules. This sexual reproduction without the need for another individual of the same species gives the plant a certain set of advantages.

I would respectfully disagree. I think staminate plants are vital to the continued development of superior cannabis.

Why I don't believe in fucking with the sexuality of cannabis

I don't care how outstanding my pistillate plants are, the staminate plants always bring something to the mix the pistillate plants just don't possess: An intensity and a vigor that is quite unique. If you don't have the patience and skill to develop cannabis without chemical manipulation of...

www.icmag.com

 

[acespicoli]

Revisiting the model for the evolution of plant sex chromosomes with C. sativa. ​

A) The current model for the evolution of plant sex chromosomes is as follows: ​

1) Sex chromosomes originate from autosomes on which sex-determining genes evolve, ​

2) The region encompassing the sex-determining genes stops recombining, ​

3) the non-recombining region grows larger due to additional events of recombination suppression, ​

4) the nonrecombining region of the Y chromosome accumulates repeats and can become larger than the corresponding region on the X chromosome, ​

5-6) the Y chromosome undergoes large deletions, and ultimately becomes smaller than the X chromosome. Steps 1-4 have been previously documented in plants (e.g. (Charlesworth et al. 2005; Ming et al. 2011; Muyle et al. 2017) for review) while steps 5-6 are very speculative. Our study is supportive of this scenario if we assume that the C. sativa Y chromosome has been larger in the past. ​

​

B) It is possible however that the accumulation of repeats has been slow in the Y chromosome of the C. sativa lineage and that X and Y chromosomes have always been of similar size (see text). ​

Here step 4 does not imply the elongation of Y chromosome.​

...

Journal Reference:

1. Kaitlin U Laverty, Jake M Stout, Mitchell J Sullivan, Hardik Shah, Navdeep Gill, Larry Holbrook, Gintaras Deikus, Robert Sebra, Timothy R Hughes, Jonathan E Page, Harm van Bakel.
2. A physical and genetic map of Cannabis sativa identifies extensive rearrangement at the THC/CBD acid synthase locus. Genome Research, 2018; gr.242594.118 DOI: 10.1101/gr.242594.118

Genome Res.-2019-Laverty-146-56.pdf

drive.google.com

---

University of Toronto. "How ancient viruses got cannabis high." ScienceDaily. ScienceDaily, 26 November 2018. <www.sciencedaily.com/releases/2018/11/181126105506.htm>.


Genome Res. 2020 Feb; 30(2): 164–172.
doi: 10.1101/gr.251207.119
PMCID: PMC7050526
PMID: 32033943

An efficient RNA-seq-based segregation analysis​

identifies the sex chromosomes of Cannabis sativa​

Abstract​

Moreover, as dioecy in the Cannabaceae family is ancestral, C. sativa sex chromosomes are potentially old and thus very interesting to study, as little is known about old plant sex chromosomes. Here, we RNA-sequenced a C. sativa family (two parents and 10 male and female offspring, 576 million reads) and performed a segregation analysis for all C. sativa genes using the probabilistic method SEX-DETector. We identified >500 sex-linked genes. Mapping of these sex-linked genes to a C. sativa genome assembly identified the largest chromosome pair being the sex chromosomes. We found that the X-specific region (not recombining between X and Y) is large compared to other plant systems. Further analysis of the sex-linked genes revealed that C. sativa has a strongly degenerated Y Chromosome and may represent the oldest plant sex chromosome system documented so far. Our study revealed that old plant sex chromosomes can have large, highly divergent nonrecombining regions, yet still be roughly homomorphic.

Plant genera Cannabis and Humulus share the same pair of well-differentiated sex chromosomes​

Djivan Prentout, Natasa Stajner, Andreja Cerenak, Theo Tricou, Celine Brochier-Armanet, Jernej Jakse, Jos Käfer, Gabriel A. B. Marais
First published: 12 May 2021

https://doi.org/10.1111/nph.17456

Summary​

• We recently described, in Cannabis sativa, the oldest sex chromosome system documented so far in plants (12–28 Myr old). Based on the estimated age, we predicted that it should be shared by its sister genus Humulus, which is known also to possess XY chromosomes.
• Here, we used transcriptome sequencing of an F1 family of H. lupulus to identify and study the sex chromosomes in this species using the probabilistic method SEX-DETector.
• We identified 265 sex-linked genes in H. lupulus, which preferentially mapped to the C. sativa X chromosome. Using phylogenies of sex-linked genes, we showed that a region of the sex chromosomes had already stopped recombining in an ancestor of both species. Furthermore, as in C. sativa, Y-linked gene expression reduction is correlated to the position on the X chromosome, and highly Y degenerated genes showed dosage compensation.
• We report, for the first time in Angiosperms, a sex chromosome system that is shared by two different genera. Thus, recombination suppression started at least 21–25 Myr ago, and then (either gradually or step-wise) spread to a large part of the sex chromosomes (c. 70%), leading to a degenerated Y chromosome.

Molecular Cytogenetic Characterization of the Dioecious Cannabis sativa with an XY Chromosome Sex Determination System​

Mikhail G. Divashuk, Oleg S. Alexandrov, Olga V. Razumova, Ilya V. Kirov, and Gennady I. Karlov *
Gabriel A. B. Marais, Editor
Author information Article notes Copyright and License information PMC Disclaimer

Go to:

Abstract​

Hemp (Cannabis sativa L.) was karyotyped using by DAPI/C-banding staining to provide chromosome measurements, and by fluorescence in situ hybridization with probes for 45 rDNA (pTa71), 5S rDNA (pCT4.2), a subtelomeric repeat (CS-1) and the Arabidopsis telomere probes. The karyotype has 18 autosomes plus a sex chromosome pair (XX in female and XY in male plants). The autosomes are difficult to distinguish morphologically, but three pairs could be distinguished using the probes. The Y chromosome is larger than the autosomes, and carries a fully heterochromatic DAPI positive arm and CS-1 repeats only on the less intensely DAPI-stained, euchromatic arm. The X is the largest chromosome of all, and carries CS-1 subtelomeric repeats on both arms. The meiotic configuration of the sex bivalent locates a pseudoautosomal region of the Y chromosome at the end of the euchromatic CS-1-carrying arm. Our molecular cytogenetic study of the C. sativa sex chromosomes is a starting point for helping to make C. sativa a promising model to study sex chromosome evolution.
...

in some cases, cross-pollination with cultivated varieties resulted in the loss of the wild species.

Recombinant DNA - Wikipedia

en.wikipedia.org

 

[acespicoli]

Front. Plant Sci., 05 June 2024
Sec. Plant Breeding
Volume 15 - 2024 | https://doi.org/10.3389/fpls.2024.1412079

Why not XY?​

Male monoecious sexual phenotypes challenge the female monoecious paradigm​

in Cannabis sativa L.​

Current evidence suggests partial recombination is possible between the X and Y chromosomes in the male parent due to a pseudo autosomal region on the sex chromosomes (Peil et al., 2003).

...
Not to stir up a battle of the sexes, but the X chromosome (females have two of them, while males have one) is five times larger than the Y chromosome, and has 10 times the number of genes.
That means it carries more traits — and diseases — than the Y chromosome.
...

X-linked recessive inheritance - Wikipedia

en.wikipedia.org

Plant sex determination and sex chromosomes​

Heredity volume 88, pages94–101 (2002)Cite this article

Abstract​

Sex determination systems in plants have evolved many times from hermaphroditic ancestors (including monoecious plants with separate male and female flowers on the same individual), and sex chromosome systems have arisen several times in flowering plant evolution. Consistent with theoretical models for the evolutionary transition from hermaphroditism to monoecy, multiple sex determining genes are involved, including male-sterility and female-sterility factors. The requirement that recombination should be rare between these different loci is probably the chief reason for the genetic degeneration of Y chromosomes. Theories for Y chromosome degeneration are reviewed in the light of recent results from genes on plant sex chromosomes.

Hermaphroditic plants are thought to be the ancestors of most flowering plants and vascular plants. Hermaphroditic plants can reproduce as both male and female,
which can be advantageous when colonizing new environments.
For example, many plant species that colonize remote oceanic islands are hermaphroditic.

https://www.nationsonline.org/oneworld/map/oceania_map.htm#google_vignette

Large-scale whole-genome resequencing​

unravels the domestication history of Cannabis sativa​

• July 2021

DOI:10.1126/sciadv.abg2286

Y does the male chromosome not have all the extra DNA

 

[acespicoli]

The degeneration of Y chromosomes​

Brian Charlesworth and Deborah Charlesworth
Published:29 November 2000 https://doi.org/10.1098/rstb.2000.0717

Abstract​

Y chromosomes are genetically degenerate, having lost most of the active genes that were present in their ancestors. The causes of this degeneration have attracted much attention from evolutionary theorists. Four major theories are reviewed here: Muller's ratchet, background selection, the Hill–Robertson effect with weak selection, and the ‘hitchhiking’ of deleterious alleles by favourable mutations. All of these involve a reduction in effective population size

...

People think im crazy when I tell the to keep the hermi male's in their seed lines
That may be true, but...

 

[acespicoli]

Sex chromosomes in flowering plants†​

Ray Ming, Jianping Wang, Paul H. Moore, Andrew H. Paterson
First published: 01 February 2007

https://doi.org/10.3732/ajb.94.2.141
Citations: 96
†
The authors thank M. Moore for editing the manuscript. This work was supported by a grant from the National Science Foundation to R.M., Q.Y., P.H.M., J.J., and A.H.P. (DBI-0553417) and with startup funds from the University of Illinois at Urbana–Champaign to R.M.

SECTIONS

Abstract​

Sex chromosomes in dioecious and polygamous plants evolved as a mechanism for ensuring outcrossing to increase genetic variation in the offspring. Sex specificity has evolved in 75% of plant families by male sterile or female sterile mutations, but well-defined heteromorphic sex chromosomes are known in only four plant families. A pivotal event in sex chromosome evolution, suppression of recombination at the sex determination locus and its neighboring regions, might be lacking in most dioecious species. However, once recombination is suppressed around the sex determination region, an incipient Y chromosome starts to differentiate by accumulating deleterious mutations, transposable element insertions, chromosomal rearrangements, and selection for male-specific alleles. Some plant species have recently evolved homomorphic sex chromosomes near the inception of this evolutionary process, while a few other species have sufficiently diverged heteromorphic sex chromosomes. Comparative analysis of carefully selected plant species together with some fish species promises new insights into the origins of sex chromosomes and the selective forces driving their evolution.
...

• Heteromorphic

• Definition​

  Referring to structures or organs within a species or individual that differ in form or size;
• Related Terms
  Dimorphic
  Monomorphic

 

[acespicoli]

Sex chromosomes in flowering plants†​

Ray Ming, Jianping Wang, Paul H. Moore, Andrew H. Paterson
First published: 01 February 2007

https://doi.org/10.3732/ajb.94.2.141
Citations: 96
†
The authors thank M. Moore for editing the manuscript. This work was supported by a grant from the National Science Foundation to R.M., Q.Y., P.H.M., J.J., and A.H.P. (DBI-0553417) and with startup funds from the University of Illinois at Urbana–Champaign to R.M.

SECTIONS

Abstract​

Sex chromosomes in dioecious and polygamous plants evolved as a mechanism for ensuring outcrossing to increase genetic variation in the offspring. Sex specificity has evolved in 75% of plant families by male sterile or female sterile mutations, but well-defined heteromorphic sex chromosomes are known in only four plant families. A pivotal event in sex chromosome evolution, suppression of recombination at the sex determination locus and its neighboring regions, might be lacking in most dioecious species. However, once recombination is suppressed around the sex determination region, an incipient Y chromosome starts to differentiate by accumulating deleterious mutations, transposable element insertions, chromosomal rearrangements, and selection for male-specific alleles. Some plant species have recently evolved homomorphic sex chromosomes near the inception of this evolutionary process, while a few other species have sufficiently diverged heteromorphic sex chromosomes. Comparative analysis of carefully selected plant species together with some fish species promises new insights into the origins of sex chromosomes and the selective forces driving their evolution.

• Heteromorphic

• Definition​

  Referring to structures or organs within a species or individual that differ in form or size; e.g., the simple juvenile and pinnately compound leaves of Syagrus inajai (Arecaceae). Compare with dimorphic and monomorphic.

• Related Terms​

  
  Dimorphic
  Monomorphic

Definition of DIOECIOUS

having male reproductive organs in one individual and female in another; having staminate and pistillate flowers borne on different individuals… See the full definition

www.merriam-webster.com

in many dioecious species males and females exhibit a great deal of biological and behavioral dimorphism.

 

[acespicoli]

Front. Plant Sci., 24 June 2020
Sec. Plant Systematics and Evolution
Volume 11 - 2020 | https://doi.org/10.3389/fpls.2020.00718

Hermaphroditism in Marijuana (Cannabis sativa L.) Inflorescences – Impact on Floral Morphology, Seed Formation, Progeny Sex Ratios, and Genetic Variation​

Zamir K. Punja* Janesse E. Holmes

• Department of Biological Sciences, Simon Fraser University, Burnaby, BC, Canada

Cannabis sativa L. (hemp, marijuana) produces male and female inflorescences on different plants (dioecious) and therefore the plants are obligatory out-crossers. In commercial production, marijuana plants are all genetically female; male plants are destroyed as seed formation reduces flower quality. Spontaneously occurring hermaphroditic inflorescences, in which pistillate flowers are accompanied by formation of anthers, leads to undesired seed formation; the mechanism for this is poorly understood. We studied hermaphroditism in several marijuana strains with three objectives: (i) to compare the morphological features of this unique phenotype with normal male flowers; (ii) to assess pollen and seed viability from hermaphroditic flowers; and (iii) to assess the effect of hermaphroditism on progeny male:female (sex) ratios and on genetic variation using molecular methods. The morphological features of anthers, pollen production and germination in hermaphroditic flowers and in staminate inflorescences on male plants were compared using light and scanning electron microscopy. Seeds produced on hermaphroditic plants and seeds derived from cross-fertilization were germinated and seedlings were compared for gender ratios using a PCR-based assay as well as for the extent of genetic variation using six ISSR primers. Nei’s index of gene diversity and Shannon’s Information index were compared for these two populations. The morphology of anthers and pollen formation in hermaphroditic inflorescences was similar to that in staminate flowers. Seedlings from hermaphroditic seeds, and anther tissues, showed a female genetic composition while seedlings derived from cross-fertilized seeds showed a 1:1 male:female sex expression ratio. Uniquely, hermaphroditic inflorescences produced seeds which gave rise only to genetically female plants. In PCR assays, a 540 bp size fragment was present in male and female plants, while a 390 bp band was uniquely associated with male plants. Sequence analysis of these fragments revealed the presence of Copia-like retrotransposons within the C. sativa genome which may be associated with the expression of male or female phenotype. In ISSR analysis, the percentage of polymorphic loci ranged from 44 to 72% in hermaphroditic and cross-fertilized populations. Nei’s index of gene diversity and Shannon’s Information index were not statistically different for both populations. The extent of genetic variation after one generation of selfing in the progeny from hermaphroditic seed is similar to that in progeny from cross-fertilized seeds.

Introduction​

Cannabis sativa L. (hemp, marijuana), a member of the family Cannabaceae, is a diploid (2n = 20) outcrossing plant which produces male and female inflorescences on different plants (dioecious). Dioecy is proposed to have evolved from a hermaphrodite ancestor in angiosperms and is found in about 6% of all angiosperm plant species (Renner and Ricklefs, 1995). It has been proposed that dioecy is a basic evolutionary mechanism to ensure cross-fertilization and, as a consequence, results in maintenance of high genetic diversity and heterozygosity (Dellaporta and Calderon-Urrea, 1993; Hamrick and Godt, 1996; Ainsworth, 2000). In dioecious plants, sex determination is governed by several factors: sex-determining genes and sex chromosomes, epigenetic control by DNA methylation and microRNA’s, and physiological regulation by phytohormones (Aryal and Ming, 2014; Heikrujam et al., 2015; Bai et al., 2019). Sexual dimorphism is expressed at very early stages of organ initiation or specification, with differential expression of genes in male and female tissues (Moliterni et al., 2004). Sex determining chromosomes have been reported in 40 angiosperm species, with 34 species having the XY system which includes C. sativa (Ming et al., 2011; Aryal and Ming, 2014). In this species, the karyotype consists of nine autosomes and a pair of sex chromosomes (X and Y) (Sakamoto et al., 1998). Female plants are homogametic (XX) and males are heterogametic (XY), with sex determination controlled by an X-to-autosome balance system (Ming et al., 2011). The estimated size of the haploid genome of C. sativa is 818 Mb for female plants and 843 Mb for male plants, owing to the larger size of the Y chromosome (Sakamoto et al., 1998). The development of molecular markers linked with sex expression in hemp was described in earlier work by Sakamoto et al. (1995, 2005), Mandolino et al. (1999), and Moliterni et al. (2004). Similar studies on marijuana are described in Punja et al. (2017).
Marijuana plants are grown commercially for their psychoactive compounds, which are produced in the trichomes that develop on flower bracts in female inflorescences (Andre et al., 2016). On occasion, it has been observed that hermaphroditic inflorescences can develop spontaneously (Small, 2017). These plants produce predominantly female inflorescences, but anthers (ranging from a few to many) may develop within the leaf axils or in pistillate flower buds. These hermaphroditic inflorescences can be induced by exogenous applications of different chemicals (Ram and Jaiswal, 1970, 1972; Ram and Sett, 1981), and by environmental stresses (Rosenthal, 1991; Kaushal, 2012), suggesting that external triggers and epigenetic factors may play a role. The hermaphrodite plants are functionally monoecious due to their ability to undergo self-pollination, but the impact of self-fertilization on progeny sex ratios and on genetic variation in the subsequent progeny has not been previously studied.
There are no previously published reports which describe the morphology of hermaphroditic inflorescences in marijuana plants. In the present study, we describe the morphological features of this unique phenotype. Anther formation, pollen production and germination were studied using light and scanning electron microscopy. We also describe for the first time the effect of hermaphroditic seed formation on the resulting female:male sex ratio using a PCR-based gender identification method. We assessed the extent of genetic variation in the progeny from self-fertilized seeds and compared that to seed derived from cross-fertilization using inter-simple sequence repeats or microsatellites (ISSR) markers. This study is the first to characterize the outcome of hermaphroditism in C. sativa. The results have an important bearing on the utility of hermaphrodites for the production of feminized (selfed) seed in the cannabis industry.

​

Discussion​

The spontaneous development of hermaphroditic inflorescences (pistillate flowers containing anthers) on female plants during commercial marijuana cultivation creates a problem for growers, since the resulting seed formation reduces the quality of the harvested flower (Small, 2017). The allocation of resources by the female plant to pollen production, followed by seed production, can result in disproportionately lower levels of terpenes and essential oils (by up to 56%) in the pollinated flowers compared to unfertilized female flowers (Meier and Mediavilla, 1998). Therefore, inflorescences containing seeds are of lower quality and frequently not suited for sale. Unpollinated female flowers, on the other hand, continue to expand growth of the style-stigma tissues, potentially to increase opportunities for attracting pollen (Small and Naraine, 2015), and consequently are more desirable commercially. In the present study, we observed spontaneous formation of hermaphroditic flowers on 5–10% of plants of three different strains of marijuana grown indoors under commercial conditions. In most cases, small clusters of anthers developed within certain female flowers, replacing the pistil. In rare cases (two out of 1,000 plants), the entire female inflorescence was displaced by large numbers of clusters of anthers instead of pistils (Figure 3). The factors which trigger this change in phenotype have not been extensively researched. This is due, in part, to the restrictions placed by government regulatory agencies on conducting research experiments on flowering cannabis plants (including in Canada), which reduces the opportunity to conduct the types of controlled experiments that are needed to elucidate the basis for hermaphroditism.
In earlier research, induction of hermaphroditism in marijuana plants was achieved experimentally by applications of gibberellic acid (Heslop-Harrison, 1956, 1957; Ram and Jaiswal, 1970, 1972, 1974; Galoch, 1978; Rosenthal, 1991; United Nations Office on Drugs and Crime [UNOCD], 2009). Other studies showed that male and female flower ratios in marijuana plants could be altered by applications of chemicals such as 2-chloroethanephosphonic acid, aminoethoxyvinylglycine, silver nitrate, silver thiosulfate, or cobalt chloride (Ram and Jaiswal, 1970, 1972; Ram and Sett, 1981). Silver nitrate inhibits ethylene action in plants (Kumar et al., 2009) and was reported to increase male sex expression in marijuana, cucumber and gourd plants (Atsmon and Tabbak, 1979; Ram and Sett, 1982; Stankovic and Prodanovic, 2002). In a recent study, applications of silver thiosulfate induced male flower formation on genetically female hemp plants (Lubell and Brand, 2018). These findings demonstrate that changes in growth regulator levels in treated plants can impact hermaphroditic flower formation.
Physical or chemical stresses can also have a role in inducing staminate flower development on female plants of marijuana. For example, external environmental stresses, e.g., low photoperiods and reduced temperatures in outdoor production, were reported to increase staminate flower formation (Kaushal, 2012). Some plants formed hermaphroditic flowers when female plants were exposed to extended periods of darkness early during growth or during altered photoperiods during the flowering stage, although the exact conditions were not described (Rosenthal, 1991, 2000). Such stress factors could affect internal phytohormone levels, such as auxin:gibberellin ratios (Tanimoto, 2005), which could in turn trigger hermaphroditic flower formation in marijuana plants. In Arabidopsis plants, auxin, gibberellin and ethylene interact with jasmonic acid (JA) to alter stamen production (Song et al., 2013, 2014). Consequently, jasmonic-acid deficient mutant Arabidopsis plants exhibited male sterility, with arrested stamen development and non-viable pollen (Jewell and Browse, 2016) while JA treatment restored stamen development in these mutants. In marijuana plants, environmental stress factors which enhance JA production could potentially promote hermaphroditic flower formation but this requires further study. Lability of sex expression may offer advantages in promoting seed formation in hermaphroditic plants subject to environmentally stressful conditions (Ainsworth, 2000).
In the present study, pollen germination and germ tube growth were observed in samples of hermaphrodite flowers and pollen transfer from male flowers to stigmas of female flowers showed germination in situ followed by germ tube growth and penetration of the stigmatic papilla. Small and Naraine (2015) and Small (2017) showed pollen grains attached to stigmatic papillae but the germination and penetration process was not described. We observed a row of bulbous trichomes forming along the stomium on the anthers in staminate flowers and in hermaphroditic flowers, confirming earlier descriptions by Potter (2009) and Small (2017) for staminate flowers. The function of these trichomes is unknown. The findings described here are the first to demonstrate viable pollen production and anther morphology in hermaphroditic flowers in marijuana.
In Mercurialis annua, a plant species that exhibits trioecy (co-occurrence of male, female, and hermaphrodites), male plants were observed to produce substantially more pollen than hermaphrodites (Perry et al., 2012). Our visual observations of male flowers of marijuana indicate significantly more pollen was produced and released compared to hermaphroditic flowers. These male plants released pollen over a period of 2–4 weeks; estimates are that each male flower can produce as many as 350,000 pollen grains (DeDecker, 2019). While the proportion of hermaphrodites in populations of marijuana is unknown, the frequency of seed formation within the hermaphroditic flower during indoor production is likely greater, despite the lower amounts of pollen produced, compared to a female flower dependent on wind-dispersed pollen from a male plant (indoors or outdoors). The distance over which pollen is dispersed from individual anthers in hermaphroditic flowers is probably limited to a few meters in indoor or outdoor growing facilities, compared to up to 3–5 km from male plants grown under outdoor field conditions, depending on wind speed and direction (Small and Antle, 2003). Male plants grow faster and are taller than female plants grown over the same time period, ensuring more rapid development of flowers and pollen dehiscence (Figure 7). However, the complete exclusion of male plants in indoor marijuana production suggests that the majority of seed formed would be the result of selfing. In outdoor cultivation of marijuana, where there could be several pollen sources, there is a greater likelihood of obtaining seeds that are the consequence of both self-fertilization and cross-fertilization. In Figure 10C, seeds collected from an outdoor field site showed two male plants and 14 females, contrary to the expectation of all females if they were from hermaphrodite selfing. The only explanation for the two males is that they originated from cross-fertilization with pollen from a male plant. Seeds collected from hermaphroditic flowers in indoor production in the present study all gave rise to seedlings which expressed the female genotype in a PCR-based test, compared to an approximately 1:1 ratio of male: female plants from cross-fertilized seeds. The primers amplified a 390 bp band which was present only in male marijuana plants, and a 540 bp fragment was present in male and female plants. Sequences comprising the male-specific 390 bp band were highly conserved among the 10 marijuana strains examined, and they differed from the 540 bp fragment through internal deletions of approximately 170 bp in size. Furthermore, detailed sequence comparisons of the 540 bp band showed variation due to the presence of a number of single-nucleotide polymorphisms. The internal deletion and SNP’s observed in these bands have not been previously described for Cannabis sativa. In the dioecious plant Silene latifolia (white campion), a hermaphrodite-inducing mutation was found to be localized to the Y chromosome in the gynoecium-suppression region (Miller and Kesseli, 2011). The Y chromosome plays a key role in sex determination in S. latifolia, and three sex-determining regions have been identified on the Y: the female suppressor region, an early stamen development region, and a late stamen development region. When hermaphrodites were used as pollen donors, the sex ratio of offspring they produced through crosses was biased toward females.
Molecular markers have been described to distinguish between male and female plants in hemp. Using RAPD markers, Sakamoto et al. (1995) observed two DNA fragments (500 and 730 bp in size) to be present in male plants and absent in female plants. The 730 bp DNA fragment was named MADC1 (male-associated DNA sequence in Cannabis sativa). The sequence of MADC1 did not exhibit any significant similarity to previously reported sequences. In a study by Mandolino et al. (1999), RAPD analysis revealed the association of a 400 bp band consistently with male hemp plants. Following sequence characterization of this MADC2, a low homology (54.8–59.8%) was found to retrotransposon-like elements in plants but not to MADC1. Sakamoto et al. (2005) conducted further RAPD analysis to identify additional male-specific bands in hemp (MADC3 – 771 bp in size and MADC4 – 576 bp in size) which were characterized as retrotransposable elements and reported to be present on the Y chromosome as well as on other chromosomes in male plants. Torjek et al. (2001) reported additional male-specific sequences MACS5 and MADC6 in hemp which were not homologous to any previously published sequence. Furthermore, conserved domain analysis indicated the presence of either a rve Superfamily integrase core domain alone or in conjunction with a pre-integrase GAG domain, both of which are potential features of LTR retrotransposons (Llorens et al., 2011). These previous studies suggest there are multiple sequences within the C. sativa genome that are associated with the male genotype, but which can also occur on other chromosomes (autosomes), many of which have similarities to transposons.
Transposable elements (TEs) have been found throughout eukaryotic genomes, including those of yeast, drosophila, rice and humans (Chénais et al., 2012). In C. sativa, Sakamoto et al. (2005) showed the presence of multiple Copia-like retrotransposon locations along the Y chromosome and throughout the autosomes in hemp. In the present study, a GAG pre-integrase domain was found upstream of the rve Superfamily domain in three female marijuana strains. Both domains are features of Class I LTR retrotransposons (Wicker et al., 2007; Llorens et al., 2011). According to NCBI’s Conserved Domain Database, the GAG pre-integrase domain (pfam13976) is associated with retroviral insertion elements. In addition, the placement of these domains is characteristic of the Copia Superfamily of LTR retrotransposons (Wicker et al., 2007). Therefore, the presence of Copia-like retrotransposons within the C. sativa genome is confirmed, but their functions or association with the expression of male or female phenotype remains to be determined.
Estimates of the degree of genetic variation (diversity) among plant populations have been obtained using isozyme markers (Cole, 2003), chloroplast DNA markers (Carvalho et al., 2019), nuclear DNA-based markers (Govindaraj et al., 2015; Bhandari et al., 2017), and single nucleotide polymorphisms (Pucholt et al., 2017; Zhang et al., 2017). In hemp, previous studies on genetic diversity assessment have utilized RAPD markers (Faeti et al., 1996; Forapani et al., 2001; Mandolino and Ranalli, 2002). Microsatellite markers, in particular, have attracted interest as a tool to assess genetic diversity in a range of plant species, including those that are diecious (Barker et al., 2003; Teixeira et al., 2009; Dering et al., 2016; Szczecińska et al., 2016; Zhai et al., 2016; Kumar and Agrawal, 2019). Measures of genetic variability are expressed as the percent of polymorphic loci (P), number of alleles per locus (A), expected and observed heterozygosity (HE, HO) and number of alleles per polymorphic loci (AP). Increased inbreeding (through selfing) and reduced frequency of polymorphic loci can result in lower levels of expected heterozygosity, particularly in small, isolated self-compatible plant species (Cole, 2003). In a dioecious out-crossing plant such as C. sativa, the low levels of self-pollination and extensive existing genetic variation would predict a minimal impact of hermaphroditism on genetic variation. The six-primer microsatellite set used in this study to compare the two populations originating from hermaphroditic and cross-fertilized seeds showed that the percentage of polymorphic loci, the effective number of alleles (Ne), Nei’s gene diversity (H) and Shannon’s index values had overlapping mean values and standard deviations, and were shown to not be statistically different. This indicates there was no measurable difference in the level of genetic variation between the hermaphroditic populations when compared to the cross-fertilized populations. One cycle of self-fertilization, which is the outcome from hermaphroditic seed production through selfing, may not have caused a measurable difference due to the high level of predicted heterozygosity in C. sativa (Small, 2017). Inbreeding can reduce the fitness of the inbred relative to outbred offspring, due to an increase of homozygous loci in the former (Charlesworth and Charlesworth, 1987). Populations that are typically outcrossing are expected to exhibit higher levels of inbreeding depression, on average, than populations that are typically selfing (Husband and Schemske, 1996). In a study involving dioecious Mercurialis annua, the degree of inbreeding depression (measured as seed germination, early and late plant survival, seed mass and pollen viability) was compared between outcrossed progeny and the progeny of self-fertilized feminized males (Eppley and Pannell, 2009); the findings revealed that inbreeding depression was low. Similarly, in populations of another dioecious plant, Amaranthus cannabinus, the effects of inbreeding on seed germination, leaf size and plant height were found to be minimal (Bram, 2002). In several dioecious plants, mechanisms to prevent inbreeding depression through selfing occur (Teixeira et al., 2009). Additional studies to determine the effects of sequential cycles of selfing on genetic variation in C. sativa should provide insight into whether the frequency of polymorphic loci is reduced and whether seed and plant performance measures are altered. The results from the present study suggest that one cycle of selfing to produce feminized seed (Lubell and Brand, 2018) has no measurable impact on genetic diversity in that population.

Data Availability Statement​

The datasets generated for this study can be found in the NCBI – Genbank, Accession Numbers: MK093854, MK093855, MK093856, MK093857, MK093858, MK093859, MK093860, MK093861, and MK093862.

...​

In ISSR analysis, the percentage of polymorphic loci ranged from 44 to 72% in hermaphroditic and cross-fertilized populations. Nei’s index of gene diversity and Shannon’s Information index were not statistically different for both populations. The extent of genetic variation after one generation of selfing in the progeny from hermaphroditic seed is similar to that in progeny from cross-fertilized seeds.

Polymorphic has multiple meanings:

• Biology: A species is polymorphic when it has more than one form or type, also known as alternative phenotypes, as a result of discontinuous variation. For example, a gene is polymorphic if more than one allele occupies that gene's locus within a population, and each allele occurs in the population at a rate of at least 1%.

1:100
...

 

[acespicoli]

Measures of genetic variability are expressed as the percent of polymorphic loci (P), number of alleles per locus (A), expected and observed heterozygosity (HE, HO) and number of alleles per polymorphic loci (AP). Increased inbreeding (through selfing) and reduced frequency of polymorphic loci can result in lower levels of expected heterozygosity, particularly in small, isolated self-compatible plant species (Cole, 2003).

In a dioecious out-crossing plant such as C. sativa, the low levels of self-pollination and extensive existing genetic variation would predict a minimal impact of hermaphroditism on genetic variation. The six-primer microsatellite set used in this study to compare the two populations originating from hermaphroditic and cross-fertilized seeds showed that the percentage of polymorphic loci, the effective number of alleles (Ne), Nei’s gene diversity (H) and Shannon’s index values had overlapping mean values and standard deviations, and were shown to not be statistically different. This indicates there was no measurable difference in the level of genetic variation between the hermaphroditic populations when compared to the cross-fertilized populations. One cycle of self-fertilization, which is the outcome from hermaphroditic seed production through selfing, may not have caused a measurable difference due to the high level of predicted heterozygosity in C. sativa (Small, 2017).

Inbreeding can reduce the fitness of the inbred relative to outbred offspring, due to an increase of homozygous loci in the former (Charlesworth and Charlesworth, 1987).

Populations that are typically outcrossing are expected to exhibit higher levels of inbreeding depression, on average, than populations that are typically selfing (Husband and Schemske, 1996).

In a study involving dioecious Mercurialis annua, the degree of inbreeding depression (measured as seed germination, early and late plant survival, seed mass and pollen viability) was compared between outcrossed progeny and the progeny of self-fertilized feminized males (Eppley and Pannell, 2009); t

he findings revealed that inbreeding depression was low. Similarly, in populations of another dioecious plant, Amaranthus cannabinus, the effects of inbreeding on seed germination, leaf size and plant height were found to be minimal (Bram, 2002).

In several dioecious plants, mechanisms to prevent inbreeding depression through selfing occur (Teixeira et al., 2009).

Additional studies to determine the effects of sequential cycles of selfing on genetic variation in C. sativa should provide insight into whether the frequency of polymorphic loci is reduced and whether seed and plant performance measures are altered. The results from the present study suggest that one cycle of selfing to produce feminized seed (Lubell and Brand, 2018) has no measurable impact on genetic diversity in that population.

 

[dogzter]

I don't use any femmed or selfed genetics.
Sadly at this point that means I don't take in any outside genetics anymore.
I aint alone but there are less and less of us doing that each year........not gonna end well at the current trajectory?

 

[acespicoli]

“Functional wasteland,” “Nonrecombining desert,” and “Gene-poor chromosome” are only some examples of the different definitions given to the Y chromosome in the last decade.

J Biomed Biotechnol. 2001; 1(1): 18–24.
doi: 10.1155/S1110724301000080

 

[acespicoli]

Origin and Evolution of the Cannabinoid Oxidocyclase Gene Family

Abstract. Cannabis is an ancient crop representing a rapidly increasing legal market, especially for medicinal purposes. Medicinal and psychoactive effects

doi.org

​

 

[acespicoli]

Abstract​

Gradual degradation seems inevitable for non-recombining sex chromosomes. This has been supported by the observation of degenerated non-recombining sex chromosomes in a variety of species. The human Y chromosome has also degenerated significantly during its evolution, and theories have been advanced that the Y chromosome could disappear within the next ∼5 million years, if the degeneration rate it has experienced continues. However, recent studies suggest that this is unlikely. Conservative evolutionary forces such as strong purifying selection and intrachromosomal repair through gene conversion balance the degeneration tendency of the Y chromosome and maintain its integrity after an initial period of faster degeneration. We discuss the evidence both for and against the extinction of the Y chromosome. We also discuss potential insights gained on the evolution of sex-determining chromosomes by studying simpler sex-determining chromosomal regions of unicellular and multicellular microorganisms.
Published online 2012 Sep 5. doi: 10.1002/bies.201200064

Should Y stay or should Y go:​

The evolution of non-recombining sex chromosomes​

 

[acespicoli]

10.1371/journal.pone.0085118

Molecular Cytogenetic Characterization of the Dioecious Cannabis sativa​

with an XY Chromosome Sex Determination System​

 

[acespicoli]

The phylogeny is according to the reference of [59]. Idiograms created based on data obtained in [21], [23], [24], [26], [55] and in this study. 5S rDNA: green signals; 45S rDNA: red signals; species-specific subtelomeric repeats (HSR-1for H. lupulus, HJSR for H. japonicus and CS-1 for C. sativa): green signal. The position of pseudoautosomal region on sex chromosomes is indicated by brackets. Time of divergence estimated in [60], [61], [62].​

An efficient RNA-seq-based segregation analysis identifies the sex chromosomes of Cannabis sativa

Cannabis sativa–derived tetrahydrocannabinol (THC) production is increasing very fast worldwide. C. sativa is a dioecious plant with XY Chromosomes, and only females (XX) are useful for THC production. Identifying the sex chromosome sequence would ...

www.ncbi.nlm.nih.gov

Mapping of these sex-linked genes to a C. sativa genome assembly identified the largest chromosome pair being the sex chromosomes. We found that the X-specific region (not recombining between X and Y) is large compared to other plant systems. Further analysis of the sex-linked genes revealed that C. sativa has a strongly degenerated Y Chromosome and may represent the oldest plant sex chromosome system documented so far. Our study revealed that old plant sex chromosomes can have large, highly divergent nonrecombining regions, yet still be roughly homomorphic.

ONE DETAIL ID LIKE TO DISCUSS IF YOUR FOLLOWING IS
strongly degenerated Y Chromosome, AND WHY ?

 

[acespicoli]

Outcrossing in plants and fungi​

[edit]
Outcrossing in plants is usually enforced by self-incompatibility. The primary adaptive function of flowers is the facilitation of outcrossing, a process that allows the masking of deleterious mutations in the genome of progeny. The masking effect of outcrossing is known as genetic complementation,[3] an effect also recognized as hybrid vigor or heterosis. Once outcrossing is established in a lineage of flowering plants due to the benefit of genetic complementation, subsequent switching to inbreeding becomes disadvantageous because it allows expression of the previously masked deleterious recessive mutations, i.e. inbreeding depression.

Outcrossing in fungi involves syngamy between haploid cells produced by separate diploid individuals.[4]

Life-history traits are said to increase the probability of outcrossing in fungi, such as long-distance dispersal and persistence of the haploid stage. Some studies even show that fungi favor outcrossing in comparison to other mating types. In a study performed with the commercial button mushroom, Agaricus bisporus, outcrossed populations of the fungi showed higher fitness than inbred ones in several fitness components.[5]

General practice​

[edit]
Breeders inbreed within their genetic pool, attempting to maintain desirable traits and to cull those traits that are undesirable. When undesirable traits begin to appear, mates are selected to determine if a trait is recessive or dominant. Removal of the trait is accomplished by breeding two individuals known not to carry it.[6]

Gregor Mendel used outcrossing in his experiments with flowers. He then used the resulting offspring to chart inheritance patterns, using the crossing of siblings, and backcrossing to parents to determine how inheritance functioned.[7]

Darwin's perspective​

[edit]
Charles Darwin, in his book The Effects of Cross and Self-Fertilization in the Vegetable Kingdom,.[8]: 462  stated regarding outcrossing that "the offspring from the union of two distinct individuals, especially if their progenitors have been subjected to very different conditions, have an immense advantage in height, weight, constitutional vigor and fertility over the self-fertilizing offspring from either one of the same parents". He thought that this observation was amply sufficient to account for outcrossing sexual reproduction. The disadvantages of self-fertilized offspring (inbreeding depression) are now thought to be largely due to the homozygous expression of deleterious recessive mutations;[9] and the fitness advantages of some outcrossed offspring are thought to be largely due to the heterozygous masking of such deleterious mutations except when such mutations lead to outbreeding depression.

Outcrossing - Wikipedia

en.wikipedia.org

 

[acespicoli]

The primary adaptive function of flowers is the facilitation of outcrossing, a process that allows the masking of deleterious mutations in the genome of progeny. The masking effect of outcrossing is known as genetic complementation,[3] an effect also recognized as hybrid vigor or heterosis. Once outcrossing is established in a lineage of flowering plants due to the benefit of genetic complementation, subsequent switching to inbreeding becomes disadvantageous because it allows expression of the previously masked deleterious recessive mutations, i.e. inbreeding depression.

ANOTHER TERM THAT COMES UP OFTEN
deleterious mutations

 

[acespicoli]

Perfection is the enemy of evolution​

• DOI: 10.1016/j.biosystems.2023.104917

https://en.wikipedia.org/wiki/Speciation

Mutation - Wikipedia

en.wikipedia.org

The multiple sources of genetic variation include mutation and genetic recombination.[3]
In population genetics, F-statistics (also known as fixation indices) describe the statistically expected level of heterozygosity in a population; more specifically the expected degree of (usually) a reduction in heterozygosity when compared to Hardy–Weinberg expectation.

F-statistics can also be thought of as a measure of the correlation between genes drawn at different levels of a (hierarchically) subdivided population. This correlation is influenced by several evolutionary processes, such as genetic drift, founder effect, bottleneck, genetic hitchhiking, meiotic drive, mutation, gene flow, inbreeding, natural selection, or the Wahlund effect, but it was originally designed to measure the amount of allelic fixation owing to genetic drift.

The concept of F-statistics was developed during the 1920s by the American geneticist Sewall Wright,[1][2] who was interested in inbreeding in cattle. However, because complete dominance causes the phenotypes of homozygote dominants and heterozygotes to be the same, it was not until the advent of molecular genetics from the 1960s onwards that heterozygosity in populations could be measured.

F can be used to define effective population size.

Molecular Cytogenetic Characterization of the Dioecious Cannabis sativa with an XY Chromosome Sex Determination System​

https://doi.org/10.1371/journal.pone.0085118