http://www.cra-pav.it/petria/n19/19-3.pdf
Induction of resistance IN THE control of
phytoplasma diseasesPhytoplasma are small, insect-transmitted, cell-wall-less bacteria that cause
numerous diseases in economically and environmentally important plant species
worldwide (McCoy et al., 1989; Lee et al., 2000; Seemüller et al., 2002; Martelli
and Boudon-Padieu, 2006; Weintraub and Beanland, 2006; Bertaccini et al., 2007;
Firrao et al., 2007; Hogenhout et al., 2008). The impossibility of cultivating them
in vitro has blocked the development of methods of control against these pathogens.
Indeed, other strategies have been tested, namely: (i) production of transgenic plants
expressing antibodies against the major phytoplasma membrane protein (Le Gall et al.,
1998; Malembic-Maher et al., 2005); (ii) production of transgenic plants expressing
antimicrobial peptides (Zhao et al., 2004; Du et al., 2005); and (iii) protecting the
plants using elicitins (cryptogein or oligandrin), small proteins that stimulate P protein
plugs and callose release in phloem sieve elements (Lherminier et al., 2003). Other
approaches for the control of phytoplasma are not directed against the pathogen, but
are based instead on the selection of resistant, tolerant or immune plant varieties. They
have so far been investigated by phytoplasma inoculation, symptom observation and
variety selection (Jaraush et al., 1999; Sinclair et al., 2000), and also marker-assisted
selection programmes (Cardena et al., 2003). This undirected control strategy is not
always possible, because not all phytoplasma-infected plant species show resistance
or tolerance versus to disease. A promising approach has become more prominent
recently through significant studies of different groups that have addressed the
exploitation of knowledge concerning natural or induced resistance to plant bacteria,
and in particular to phytoplasma. Indeed, the existence of different forms of life within
the plant is a basic concept that can be developed for the design of possible alternatives
and strategies for phytoplasma disease control.
numerous diseases in economically and environmentally important plant species
worldwide (McCoy et al., 1989; Lee et al., 2000; Seemüller et al., 2002; Martelli
and Boudon-Padieu, 2006; Weintraub and Beanland, 2006; Bertaccini et al., 2007;
Firrao et al., 2007; Hogenhout et al., 2008). The impossibility of cultivating them
in vitro has blocked the development of methods of control against these pathogens.
Indeed, other strategies have been tested, namely: (i) production of transgenic plants
expressing antibodies against the major phytoplasma membrane protein (Le Gall et al.,
1998; Malembic-Maher et al., 2005); (ii) production of transgenic plants expressing
antimicrobial peptides (Zhao et al., 2004; Du et al., 2005); and (iii) protecting the
plants using elicitins (cryptogein or oligandrin), small proteins that stimulate P protein
plugs and callose release in phloem sieve elements (Lherminier et al., 2003). Other
approaches for the control of phytoplasma are not directed against the pathogen, but
are based instead on the selection of resistant, tolerant or immune plant varieties. They
have so far been investigated by phytoplasma inoculation, symptom observation and
variety selection (Jaraush et al., 1999; Sinclair et al., 2000), and also marker-assisted
selection programmes (Cardena et al., 2003). This undirected control strategy is not
always possible, because not all phytoplasma-infected plant species show resistance
or tolerance versus to disease. A promising approach has become more prominent
recently through significant studies of different groups that have addressed the
exploitation of knowledge concerning natural or induced resistance to plant bacteria,
and in particular to phytoplasma. Indeed, the existence of different forms of life within
the plant is a basic concept that can be developed for the design of possible alternatives
and strategies for phytoplasma disease control.
