Effect of maternal genotype on development ofPhaseolus vulgaris L. ×P. lunatus L. interspecific hybrid embryos

Summary

CertainPhaseolus vulgaris L. ×P. lunatus L. crosses were performed to study the effect of maternal heterozygosity on development and growth of the interspecific hybrid embryos. Interspecific embryos had a much slower growth rate in vitro compared with embryos derived from self-pollination ofP. vulgaris parents. Thus, interspecific embryos could be identified by growth rate in vitro. TheP. vulgaris maternal genotype affected both the number and size of 15-day-old interspecific embryos. Specifically, ‘76 Spartan Arrow’ produced significantly more interspecific embryos than did ‘Great Northern’ as the seed parent, while maternal intraspecific hybrids produced smaller embryos than did maternal pure lines. There were no reciprocal differences between hybrid maternal parents for embryo number or size. Embryo size at excision and final size after culturing were closely correlated (r²=+0.93). The crossP. vulgaris ‘76 Spartan Arrow’ ×P. lunatus P.I. 214170 produced both the largest mean size at excision and the fastest growth in culture, indicating that specific combining ability affected both characteristics.