PARENT SESSION
Oral Session # 33: Pathogens, Toxins, and Disease II: Plants.
Presiding: A Davelos
Tuesday, August 5. 1:30 PM to 5:00 PM, SITCC Meeting Room 201.
Fitness of wild Cucurbita pepo after introgression of transgenic resistance to zucchini yellow mosaic virus.
Laughlin, Karen*,1, Power, Alison1, Snow, Allison2, 1 Cornell University, Ithaca, NY2 Ohio State University, Columbus, OH
ABSTRACT- One risk of genetically modified (GM) virus-resistant plants is the introgression of transgenic virus-resistance into closely related wild plant populations. If disease pressure limits the wild plant population, then transgenic virus resistance could increase the fitness of the plant under virus infection and potentially increase the plant's invasive ability. We used a cultivated squash (Cucurbita pepo) engineered for resistance against zucchini yellow mosaic virus (ZYMV) and a conspecific wild squash to study the effect of a virus-resistance transgene on wild plant fitness. To mimic introgression of the virus-resistance transgene into a wild population, we crossed the GM squash with the wild squash and then backcrossed transgenic progeny into wild squash for two successive generations. We compared the fitness of wild individuals, transgenic backcross individuals and non-transgenic backcross individuals under ZYMV infection and healthy conditions. We measured total male and female flower production, fruit and seed number, and dry biomass to quantify reproductive and vegetative fitness. Under healthy conditions, wild, transgenic backcross and non-transgenic backcross individuals showed no significant difference in fitness measurements. Under ZYMV infection, transgenic backcross individuals showed significantly higher fitness than wild individuals. Non-transgenic backcross individuals also showed significantly higher reproductive fitness than wild C. pepo, though not as high as transgenic backcrosses. These results suggest that wild C. pepo fitness would increase with introgression of transgenic ZYMV-resistance if wild C. pepo populations are limited by ZYMV pressure. They also indicate that other conventional crop genes would contribute ZYMV-resistance to wild populations.
Key words: virus resistance, Cucurbita pepo, transgene, gene flow