Plant & Animal Genomes XVIII Conference

January 9-13, 2010
Town & Country Convention Center
San Diego, CA

Genetic Characterization Of Interspecific Breakdown In Cucurbita spp.

Sathish K Ponniah¹ , Yan R Tomason^{1, 2} , Gopinath Vajja¹ , Ruba Kerdieh¹ , Umesh K Reddy¹ , Padmavathi Nimmakayala¹

¹  Department of Biology, Gus R. Douglass Institute, West Virginia State University, Institute, WV 25112-1000, USA

²  Department of Plant Breeding, Dnepropetrovsk State Agrarian University, Voroshilov 25, Dnepropetrovsk 49600, Ukraine

Structural barriers to recombination in species hybrids impose rigorous elimination of gamates and zygotes that leads to interspecific breakdown (Wall 1961). Cucurbita moschata L (n=20), and C. pepo (n=20) are two species of Cucurbita that are morphologically dissimilar and genetically isolated and these species will not hybridize naturally (Whitaker 1960). Given the importance of these species in American fundamental foods, we have taken up research on pattern of segregation and identification of quantitative traits related to fruits. We studied fruits from 102 progenies of F₂ population (Cucurbita pepo L.X Cucurbita moschata L.) and 89 families of F₃ population. We have recorded data pertaining to fruit weight, length and width of fruits, flesh thickness, pressure of exocarp, pressure of mesocarp and soluble solids in these progenies along with their parents. We estimated Pearson correlations among the observed traits and found different degrees of association among the traits across the generations. Range of various traits indicate that the F₂ progenies undergone severe interspecific breakdown that might be due to lethal zygotes or zygote abortion or developmental restrictions due to rearrangement of coadapted modifier systems (Smith 1950). In contrary, we noticed substantial recovery of F₃ families from interspecific breakdown and produced few transgressive segregants. To exemplify the process of interspecific breakdown, SSRs and AFLPs were used across the F₂ and F₃ progenies and compared QTL inheritance for various fruit/seed related traits.