Читать книгу Dry Beans and Pulses Production, Processing, and Nutrition онлайн

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It is well recognized that during crop domestication, only a portion of the wild germplasm is domesticated, and these events are known as the founder effect. Wild germplasm is recognized as being more diverse and a potential source for valuable traits absent from the cultivated species. The best example of this are the accessions of wild P. vulgaris from Arcelia, Mexico shown to possess a unique protein trait that conditions insecticidal activities not found in the cultivated species (Cardona et al. 1989). The lectin‐like protein known as Arcelin provides resistance to the Mexican bean beetle (Zabrotes subfasciatus), which is a serious storage pest of bean seed. Since beans are cooked prior to consumption, the protein is denatured and has no negative effects on humans. The most effective Arc‐genes have been successfully backcrossed into cultivated bean varieties and are being deployed in many developing countries where the pest occurs (Kusolwa et al. 2016). Access to wild species of P. vulgaris is actually within easy reach of most breeding programs. Koinange et al. (1996) described the domestication syndrome in common bean and showed that many of the major genetic changes between wild and cultivated are controlled by relatively few loci. For example, changes in photoperiod sensitivity, growth habit, seed size, and pod shattering are under major gene control that reside on a relatively few chromosomes. As a result, breeders can recover cultivated plant and seed types in a few backcrosses to the cultivated parent after making the original cross with the wild species (Kelly 2004; Acosta et al. 2007). Unlike challenges in crossing between species, no special techniques are required to cross between wild and cultivated accessions of P. vulgaris. The inbred backcross method (described later in the chapter) has facilitated crossing between wild and cultivated accessions (Blair et al. 2006). The biggest obstacle to utilizing wild species is in the identification and selection of the actual wild accession used in crossing. Berny Mier y Teran et al. (2019) identified wild germplasm from different ecological zones with adaptation to intermittent drought and used them in nested recombinant inbred populations (Berny Mier y Teran et al. 2020) to move drought tolerance from wild to cultivated dry bean. Currently there are approximately 240 wild accessions of P. vulgaris in the US germplasm bank, and unless breeders attempt to utilize these materials in future breeding efforts valuable traits present in this germplasm may never be exploited.