PROGENIES OF AN INTERSPECIFIC HYBRID BETWEEN ARACHIS-HYPOGAEA AND A-STENOSPERMA - PEST RESISTANCE AND MOLECULAR HOMOGENEITY

Interspecific triploid hybrids were obtained between Arachis hypogaea L. and A. stenosperma Krapov. and W.C. Gregory by adopting hybridizati on coupled with rescue of the developing hybrid embryos. Two hexaploid hybrid populations were generated from triploids, somatically doubled (SD) and sexually polyploidized (SP) hexaploids. Microscopic screenin g for the occurrence of 2n gametes in triploid hybrids was useful to p redict the production of spontaneous hexaploids. In order to facilitat e maximum intergenomic recombination, the hexaploids were allowed to s elf for several generations (F-4) in the greenhouse. prolific vegetati ve growth, pollen stainability, and seed set were observed to decline with each selfed generation. Individuals of the F-3 generation from th e two hexaploid populations were evaluated for resistance to nematode (Meloidogyne arenaria Chitwood, race 1) and late leafspot Cercosporidi um personatum (Berk. and Curt.) Deighton under greenhouse conditions. Both SD and SP populations performed significantly better than their c ultivated parent, Sunbelt Runner, and a susceptible cultivar, Florunne r. At the DNA level, no significant differences were detected among hy brid individuals using cDNA clones and RAPD primers polymorphic for th e two parents. Seven cDNA clones were used to probe DNA from 17 F-2 in dividuals and two parents and 45 RAPD primers were used to amplify DNA from 21 F-2 and F-3 individuals. No significant differences in bandin g patterns were observed among hybrid individuals which suggested that little or no detectable intergenomic recombination had occurred.