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The findings will be published in August issue of plant biotechnology journal
Speaking to world.edu, lead researcher Orlando Borrás-Hidalgo at Center for Genetic Engineering and Biotechnology, Havana, Cuba, said “in our study, we report a novel defensin gene (NmDef02) isolated from the tobacco species Nicotiana megalosiphon, a non-cultivated wild tobacco species that is generally used as a parent in genetic tobacco breeding programs because of its high resistance towards several important pathogens.”
NmDef02 belong to a new defensin subgroup according the phylogenetic analysis.
“On the other hand, the antimicrobial activity of the recombinant NmDef02 was tested in vitro using several important plant pathogens. These experiments confirmed the efficient antimicrobial activity and broad spectrum activity of recombinant NmDef02 in vitro, inhibiting fungi as well as oomycetes.” Borrás-Hidalgo added.
Potato is a very important agronomical crop worldwide that suffers annual yield losses caused by several pathogens. Specifically, Phytophthora infestans constitute the more important disease in this crop. Many chemical applications are applied every season in order to control this disease.
“We interestingly showed for the first time a high level of potato resistance to Phytophthora infestans using a plant defensin under greenhouse and field conditions. High level of resistance has been observed in field condition and without any chemical application for two year. The yield and quality of the tubers were not affected during the two evaluations ” Borrás-Hidalgo indicated
“Finally, the present investigation shows that the expression of the NmDef02 defensin in GM potato plants demonstrated the efficacy of defensins in imparting disease resistance in crop plants and indicated that they are good candidates for crop improvement.” Borrás-Hidalgo pointed out.
The development of GM potato plant has received a mixed reaction from the scientific and environmental communities worldwide.
“Since protection against this infection is of great economical importance, the use of such GM potatoes is most attractive. Thus, this work is a major breakthrough in the field.” Gerhart Ryffel, GM potato expert at Institut für Zellbiologie (Tumorforschung), Universitätsklinikum Essen, Universität Duisburg-Essen, Germany, told world.edu
However, there are still some problems to be solved. The level of this novel defensin in the tubers has not been determined and its impact on human health has not been explored
To avoid any environmental and human health problems, Ryffel also proposed that “the transgene should be introduced without the selection marker, as this can be done with the techniques available. Such an approach would avoid criticism raised by opponents of GM crops, as they cannot argue for a distribution of the selective marker in the ecosystem. Secondly, I propose to use sterile potatoes to avoid any out-crossing of the transgene to other potatoes. This concern seems quite valid for a potato with a novel defensin, as we can never exclude completely by field experiments that the defensin NmDef02 might alter the behavior of the GM potato in the world-wide ecosystem. Although the generation of a super-weed is most unlikely, we should not take this risk as low as it may be. This is especially true, as we can readily avoid this risk in potatoes that can be propagated vegetatively.”
In another reaction to this new development, Ole Søgaard Lund, head of Danish Seed Health Centre at University of Copenhagen, told world.edu “The study represents a very important demonstration of the potential to use a plant defense gene in a cross-species GM approach. The problem addressed, potato late blight, is very important taking into account the huge amount of pesticides used to control this disease in conventional farming.”
“Both scientifically and agronomically the study thereby represents an important breakthrough – however, more research into the durability of the engineered resistance and into any eventually negative effect on growth and quality parameters of the transgenic tubers will be needed before conclusions on the long term potential of this technology can be drawn”, Lund indicated.
On the other hand, Jonathan Jones, group leader at the UK-based John Innes Centre’s Sainsbury laboratory, told word.edu “This report is promising, though there have been previous reports of defensin-mediated resistance that never were brought to market”
“Before widespread adoption, the NmDef02 protein, which is a cysteine-rich peptide containing disulphide bridges, will need to be tested for allergenicity. It might be better to use a photosynthetic gene promoter so that the defensin is only expressed in the leaves, to reduce any risk of allergenicity. It is significant that the trait confers resistance not only to Phytophthora infestans but also Alternaria solani.” Jones pointed out.
David Collinge, Head of the Research School for Biotechnology at University of Copenhagen. Denmark, pointed out to world.edu that “This pathogen is the among most adaptive and aggressive that we worry about. Given this pathogen’s proven ability to adapt to new sources of resistance, I find it risky to base any resistance (GM or conventional) on any single gene product, however effective and apparently unsurmountable.”
” There appear to be several promising alterative solutions. I believe these should be pyramided should there be a real hope in finding a sustainable solution.”, Collinge concluded.