Genetic Control of the Domestication Syndrome in Common Bean
- Epimaki M. K. Koinange,
- Shree P. Singh and
- Paul Gepts
- D ep. of Agronomy and Range Science, Univ. of California, Davis, CA 95616-8515; present address: Ministry of Agriculture, Lyamungu Res. Stn, Moshi, Tanzania
B ean Program, Centro Internacional de Agricultura Tropical, Apartado Aéreo 6713, Cali, Colombia
D ep. of Agronomy and Range Science, Univ. of California, Davis, CA 95616-8515
The marked pbenotypic differences for morphological and physiological traits that distinguish wild progenitors and cultivated descendants (“the domestication syndrome”) and the lack of information about their genetic control have limited the utilization of wild germplasm for crop involvement. This study was conducted to assess the genetic control of the domestication syndrome in common bean (Phaseolus vulgaris L.). A recombinant inbred population resulting from a cross between a wild and a cultivated common bean was subjected to molecular linkage mapping and evaluation in short-day and long-day environments. We show that the genetic control of this syndrome in common bean involves genes that can have a large effect (>25–30%) and account for a substantial part of the phenotypic variation observed (>40–50%). The distribution of domestication syndrome genes appears to be concentrations in three genomic regions with a major effect on the syndrome, one of which greatly affects growth habit and phenology, the other seed dispersal and dormancy, and a third, the size of fruit and seed, all of which are important traits in determining adaptation to a cultivated environment. Whereas the influence of genetic background and environment on the expression of some traits will have to be further analyzed, our results suggest, however, that domestication of common bean could have proceeded rapidly (provided that genetic diversity and selection intensity were high) and that evolution can proceed through changes involving a few genes with large effect rather than through a gradual accumulation of changes coded by changes with small effects. They also suggest that adaptation to rapidly changing environmental conditions may involve genes with large phenotypic effects. The information presented here should lead to marker-assisted selection experiments of introgression of additional genetic diversity into the cultivated common bean gene pool.
Copyright © . .