The Genetics of Domestication of the Azuki Bean (Vigna angularis)

Genetic differences between azuki bean (Vigna angularis var. angularis) and its presumed wild ancestor (V. angularis var. nipponensis) were resolved into QTL for traits associated with adaptation to their respective distinct habits. A genetic linkage map constructed using progenies from a cross between Japanese cultivated and wild azuki beans covers 92.8% of the standard azuki bean linkage map. A reciprocal translocation between cultivated and wild azuki bean parents was identified on the basis of the linkage map having a pseudolinkage group and clustering of seed productivity-related QTL with large effect near the presumed breakpoints. In total, 162 QTL were identified for 46 domestication-related traits. Domestication of azuki bean has involved a trade-off between seed number and seed size: fewer but longer pods and fewer but larger seeds on plants with shorter stature in cultivated azuki bean being at the expense of overall seed yield. Genes found related to germination and flowering time in cultivated azuki bean may confer a selective advantage to the hybrid derivatives under some ecological conditions and may explain why azuki bean has evolved as a crop complex in Japan

Construction of a genetic linkage map and genetic analysis of domestication related traits in mungbean (Vigna radiata).

The genetic differences between mungbean and its presumed wild ancestor were analyzed for domestication related traits by QTL mapping. A genetic linkage map of mungbean was constructed using 430 SSR and EST-SSR markers from mungbean and its related species, and all these markers were mapped onto 11 linkage groups spanning a total of 727.6 cM. The present mungbean map is the first map where the number of linkage groups coincided with the haploid chromosome number of mungbean. In total 105 QTLs and genes for 38 domestication related traits were identified. Compared with the situation in other Vigna crops, many linkage groups have played an important role in the domestication of mungbean. In particular the QTLs with high contribution were distributed on seven out of 11 linkage groups. In addition, a large number of QTLs with small contribution were found. The accumulation of many mutations with large and/or small contribution has contributed to the differentiation between wild and cultivated mungbean. The useful QTLs for seed size, pod dehiscence and pod maturity that have not been found in other Asian Vigna species were identified in mungbean, and these QTLs may play the important role as new gene resources for other Asian Vigna species. The results provide the foundation that will be useful for improvement of mungbean and related legumes

Comparison of <i>Vigna vexillata</i> linkage group with those of <i>V</i>. <i>radiata</i> and <i>V</i>. <i>unguculata</i>, and some characteristics of the constructed <i>V</i>. <i>vexillata</i> SSR linkage map.

<p>Unlinked markers: CEDG074a and VES0660</p><p>Comparison of <i>Vigna vexillata</i> linkage group with those of <i>V</i>. <i>radiata</i> and <i>V</i>. <i>unguculata</i>, and some characteristics of the constructed <i>V</i>. <i>vexillata</i> SSR linkage map.</p

Construction of an SSR and RAD-Marker Based Molecular Linkage Map of <i>Vigna vexillata</i> (L.) A. Rich

<div><p><i>Vigna vexillata</i> (L.) A. Rich. (tuber cowpea) is an underutilized crop for consuming its tuber and mature seeds. Wild form of <i>V</i>. <i>vexillata</i> is a pan-tropical perennial herbaceous plant which has been used by local people as a food. Wild <i>V</i>. <i>vexillata</i> has also been considered as useful gene(s) source for <i>V</i>. <i>unguiculata</i> (cowpea), since it was reported to have various resistance gene(s) for insects and diseases of cowpea. To exploit the potential of <i>V</i>. <i>vexillata</i>, an SSR-based linkage map of <i>V</i>. <i>vexillata</i> was developed. A total of 874 SSR markers successfully amplified single DNA fragment in <i>V</i>. <i>vexillata</i> among 1,336 SSR markers developed from <i>Vigna angularis</i> (azuki bean), <i>V</i>. <i>unguiculata</i> and <i>Phaseolus vulgaris</i> (common bean). An F₂ population of 300 plants derived from a cross between salt resistant (V1) and susceptible (V5) accessions was used for mapping. A genetic linkage map was constructed using 82 polymorphic SSR markers loci, which could be assigned to 11 linkage groups spanning 511.5 cM in length with a mean distance of 7.2 cM between adjacent markers. To develop higher density molecular linkage map and to confirm SSR markers position in a linkage map, RAD markers were developed and a combined SSR and RAD markers linkage map of <i>V</i>. <i>vexillata</i> was constructed. A total of 559 (84 SSR and 475 RAD) markers loci could be assigned to 11 linkage groups spanning 973.9 cM in length with a mean distance of 1.8 cM between adjacent markers. Linkage and genetic position of all SSR markers in an SSR linkage map were confirmed. When an SSR genetic linkage map of <i>V</i>. <i>vexillata</i> was compared with those of <i>V</i>. <i>radiata</i> and <i>V</i>. <i>unguiculata</i>, it was suggested that the structure of <i>V</i>. <i>vexillata</i> chromosome was considerably differentiated. This map is the first SSR and RAD marker-based <i>V</i>. <i>vexillata</i> linkage map which can be used for the mapping of useful traits.</p></div

RAD-seq results in parents and F₂ populations using HiSeq2000 platform.

<p>RAD-seq results in parents and F₂ populations using HiSeq2000 platform.</p

Characteristics of a <i>V</i>. <i>vexillata</i> linkage map based on the SSR and RAD markers.

<p>Characteristics of a <i>V</i>. <i>vexillata</i> linkage map based on the SSR and RAD markers.</p