-
ICMag with help from Landrace Warden and The Vault is running a NEW contest in November! You can check it here. Prizes are seeds & forum premium access. Come join in!
Female to female IBL
- Thread starter Atom
- Start date
Absolutely, It's the fastest way to get to IBL. You do not need to go beyond S4.. The risk of inbreeding depression jumps after that IMO..Ea step requires a large enough lot for testing. Making good selections along the way is essential. If you are inteseted in breeding get some books they will help..
Last edited:
goingrey
Well-known member
Using females only will make it easier to select only plants that have the traits you're looking for which may be a faster way of locking them down, but as they are so similar this may also be a faster way to inbreeding depression, sure.
In general though it's not about males or females but population size and genetic diversity and a balancing act between the two.
In general though it's not about males or females but population size and genetic diversity and a balancing act between the two.
goingrey
Well-known member
Once the traits are locked down you're done. Hang up a hammock and roll up a doob.
Or you mean to improve vigor after that? I suppose a backcross like that might provide some. But even better would be if all along you had been separately breeding another line of the same origin with the goal of locking down those particular traits. Then once you have the two IBLs like that you could cross them to make a recombinant inbred line. That breeds true for the important traits but with the heterogenic vigor of differences in other parts of the genome.
Also, just realized that atom is mota backwards!
Or you mean to improve vigor after that? I suppose a backcross like that might provide some. But even better would be if all along you had been separately breeding another line of the same origin with the goal of locking down those particular traits. Then once you have the two IBLs like that you could cross them to make a recombinant inbred line. That breeds true for the important traits but with the heterogenic vigor of differences in other parts of the genome.
Also, just realized that atom is mota backwards!
goingrey
Well-known member
Once a foreigner visiting a guru in India asked him the question, "what kind of weed should I smoke?". The guru answered, "the kind that grows in your country".
Grojak
Active member
You’re asking specific breeding question but have no idea what strain or what traits you’re looking for?
Don’t put the cart before the horse.
Lol...got it sir!
yes, but only when selfing.
pollinating one sister with another is similar to m/f, but with selfing you progress towards homozygosity faster.
the exact number of generations is a bit arbitrary indeed, but I'd not stop at s4. I have one line at s6 now, still displaying variation for some traits, still grows healthy and vigourous (but, loss of vigour from inbreeding is noticable, making an f1-hybrid with it shows that the original vigour from earlier generations is still there)
on average, each time you self you gain 50% more homozygosity. (you can reason this back using punnet squares)
so let's say you start with a plant that has 100 heterozygous genes, then at s1 50 of those will be homozygous, 50 left heterozygous.
s2: 75 of original 100 homozygous, 25 still heterozygous.
and so on.
generally in breeding/genetics, the point of declaring 'it's inbred enough now' is around s6 or s8 (depending on the source/person, and what the purpose with the inbred line is)
and for vigour, you can create 2 compatible inbred lines which when crossed will produce an f1-hybrid which is always the same, but also has access to hybrid vigour.
pollinating one sister with another is similar to m/f, but with selfing you progress towards homozygosity faster.
the exact number of generations is a bit arbitrary indeed, but I'd not stop at s4. I have one line at s6 now, still displaying variation for some traits, still grows healthy and vigourous (but, loss of vigour from inbreeding is noticable, making an f1-hybrid with it shows that the original vigour from earlier generations is still there)
on average, each time you self you gain 50% more homozygosity. (you can reason this back using punnet squares)
so let's say you start with a plant that has 100 heterozygous genes, then at s1 50 of those will be homozygous, 50 left heterozygous.
s2: 75 of original 100 homozygous, 25 still heterozygous.
and so on.
generally in breeding/genetics, the point of declaring 'it's inbred enough now' is around s6 or s8 (depending on the source/person, and what the purpose with the inbred line is)
and for vigour, you can create 2 compatible inbred lines which when crossed will produce an f1-hybrid which is always the same, but also has access to hybrid vigour.
well, sure, each actual individual plant isn't exactly 50/50, but in the grand scheme of things that's pretty irrelevant.
when you do have the facilities to do marker assisted selection you can do something with that, since then you could choose the most homozygous (or in case of backcrossing, use the one with most markers of the recurrent parent) to speed up the process, and achieve in 4 generations hat would otherwise take 6-8 generations.
but most will be close to the average 50%. more homozygous then previous gen.
you can reason it if you think of punnet squares: for each individual gene that is heterozygous in the f1, 50% (aprox.) will end up homozygous for that gene (both AA and aa), while 50% will end up heterozygous (Aa).
if that aplies to one gene among a group of offspring, the same aplies to multiple genes but within an individual offspring plant: around 25% of genes end up AA, around 25% aa, and around 50% Aa.
so yes, it's statistics and individual cases can devate from the average, but the same with the offspring ratios for a single gene. it's just usefull statistics that can be used to predict.
well, you could do that, but why? having a homozygous line is much more usefull than having some individual stud male plant. personally, I think all the talk and thinking around finding keeper/stud males around cannabis communities is kind of silly, I am not interested in males. I'm interested in female plants.
testing contribution of an individual male like that is kind of pointless imo. and I'll try to explain why, if I can find the right words.
to be clear: progeny testing is a nice tool to get info. but it also takes time and effort, so the question is really whether the info you get is worth that effort, and what you would be able to do with that info. compared to what you can do without the info.
the thing here in this specific case is, what progress you really want, what the fastest strategy is to get there, what info you need for that strategy.
so, with what you describe, the info you acquire is which individual male from a particular generation delivers the best contribution in the offspring one generation down.
however, I would want to take it multiple generations further to stabilise. so what am I going to do with that knowledge that that one particular male is the best?
because by the time I get the info which male is best, I'm already growing the next gen, and I'd want to know which of those males is the best. the old male would be useless at that point, since it's from a previous generation, and I'd have already discarded it.
also, how a particular male crosses with one ibl does not guarantee it will give through the same traits in the f1 if combined with a different ibl. so the info you get is pretty limited.
so, I'd rather hedge my bets and use a pollen mix from as many males as possible, and focus selection on the female side, keep seeds from different females seperate and evaluate them as half-sibling groups. among that next generation, identify which of these half-sibling groups has the highest average performance (average over the whole group), and within that group select the best plants to make the next generation.
also, if you are using a single father, why not just remove the males from your breeding all together and go reversed female? at least that way you have some sight on the female traits it might pass on (not the same as progeny testing, but it's at least some degree of info of what you might find in the next gen, and it doesn't take an extra gen to acquire that info like progeny testing does. and time is the biggest limiting factor in breeding)
the only point I'd be really interested in extensive progeny testing is in the final stages towards an f1-hybrid, to evaluate specific combining ability.
what you could do there for example is that you start with 2 variable(still segregating) populations that seem to combine well with eachother (based on some progeny testing). pick some number of plants you can feasibly grow (they don't need to get big, and you don't need to be able to accurately score traits). then do selfing with single seed descent: from each selfed plant you pick 1 random seed to germinate, self again, and continuee for 6 generations.
let's say the number you picked was 100. so now after 6 generations you have 100 slightly different inbred lines derived from the same original population. if you do this for both populations, you could now make 100x100 unique f1's.
now you just need to find which of those combinations is the winning combination, keep those 2 lines and discard all the rest.
ofcourse there are other strategies, but no matter what strategy I personally don't really see that much usefullness in evaluating individual male plants contribution to offspring.
you mean copy number variation of a gene influencing the level of the gene product?
true, for plants plenty of genes have multiple copies, but in practical breeding that doesn't change so much I think. because they'd probably be either clustered together and (most of the time) inherit together so it just behaves as a low expression version of the gene vs. a high expression one, inheriting in mendellian ratios. or they're not physically close together on the dna and they'd just behave as seperate genes towards the same quantitative trait when you are breeding.
either way you'd need lab tools (sequencing, pcr markers, etc) to know this stuff is behind the phenotype you see.
if you're just practically breeding without such tools and you need to look phenotypically for your selections, it doesn't really matter what the exact genetics mechanism is, you'd just use methods for breeding quantitative traits, maybe try if you can see some mendellian behaviour in the inheritance patterns pointing to a single gene having a large effect on the quantitative trait.
but, you are right that especially with natural selection often evolution works on gene expression levels rather than total absence/presence (or other changes within the coding part of the gene). but copy number variation isn't the only way to change the dosage of the gene, changes in the promoter region for example can also change expression.
for example, there are papers out there finding copy number variation for thc synthase in cannabis. however, I doubt whether that has a big effect on thc-level. there is also a paper out there linking a marker found to be associated with higher cannabinoid levels to the expression level of cbg-synthase, which suggests the available pool of cbg, the substrate for thc-synthase, is the bottle neck rather than the level of thc-synthase.
(also, a question when you find multiple copies is always whether they are all actually active copies. one first step is to exclude copies that are not intact, i.e. premature stop codons for example, but even if they are all identical so you can be sure they all make the same functional product, you'd also need to check whether all copies are actually expressed, and at what level. for example, a gene now known as cbc-synthase was first described as an inactive thc-synthase gene, since it's sequence is very similar to thc-synthase)
While there's nothing to absolutely prove the theory yet, as there's nothing to absolutely disprove it, can we ponder it's possibility? Given that in X to auto populations, the ratio of the male flower generating gene is the trigger, we do at least know that while the limits of the effects will be the limitations of resources, the affects of multiple copies of genes, as opposed to merely the presence or absence, can create a this or that phenotype expression. So it's not only how much is produced, but also what, that can be determined by numbers, rather than mere presence.
