Genome Dissection of Traits Related to Domestication in Azuki Bean (Vigna angularis) and Comparison with other Warm-season Legumes

Abstract

BackgroundThe objective of this study was to dissect into quantitative trait loci (QTLs) the large morphological and physiological differences between cultivated azuki bean (Vigna angularis) and a wild relative and to infer the commonalities of the QTLs for domestication-related traits across the Asian Vigna and with other warm-season legumes.MethodsTwo linkage maps, for the BC1F1 and F2 populations, respectively, from the same cross between azuki bean and V. nepalensis were developed. Using these linkage maps QTLs for 33 domestication-related traits were analysed and mapped. The location of mapped QTLs was compared with locations of similar QTLs in other warm-season legumes.Key ResultsQTLs were detected for seed-, pod-, stem- and leaf-related traits. Most traits were controlled by between two and nine QTLs but several traits, such as pod dehiscence, were controlled by single genes. QTLs for domestication-related traits were restricted to particular regions of the azuki bean genome, especially linkage groups 1, 2, 4, 7 and 9. Linkage groups 1 and 2 had QTLs for a suite of traits including pod size, germination, seed size and lower stem length. QTLs on linkage groups 7 and 9 were associated with upper stem length, maximum leaf size and pod and seed size. Pleiotropy or close linkage of genes for domestication-related traits is suggested in these regions. While some QTLs are common to azuki bean and other warm-season legumes, many are recorded for the first time in azuki bean.ConclusionsQTLs for a large number of domestication-related traits have been mapped for the first time in azuki bean. QTLs with unexpected effect and new QTLs for traits such as seed size have been found. The results provide a foundation that will be useful for improvement of azuki bean and related legumes.

A Major Soybean QTL,qPDH1, Controls Pod Dehiscence without Marked Morphological Change

“…Some factors other than pod morphology could be associated with pod dehiscence, such as a cell wall-degrading enzyme (Christiansen et al, 2002) and twist strength of pod wall (Isemura et al, 2007), which is presumed to be a force to dehisce pods. Very recently, the chemical composition of the pod wall in cultivars susceptible to shattering was found to differ from that in the shattering-resistant cultivars (Romkaew et al, 2008).…”

Pod Shattering: A Homologous Series of Variation Underlying Domestication and an Avenue for Crop Improvement

“…Genetic analysis of pod shattering has been carried out in various legumes including soybean [48,[93][94][95][96][97][98][99][100][101], common bean [13,44], pea [18,50,102], cowpea [49,[103][104][105][106], lentil [16,46,107], narrow-leaf lupin [47,108], azuki bean [45,109], and common vetch [43,110]. In most of the legumes that have been studied so far, pod shattering is found to be a dominant trait controlled by one or two genes or QTLs (Table 1).…”

“…In common vetch, Vicia sativa, shattering was found to be controlled by a single gene, and recessive mutants were selected during domestication for their non-shattering character [43]. Similar to common vetch, a single gene controls the shattering process in azuki bean, Vigna angularis [45,109]. In narrow-leafed lupin (Lupinus angustifolius), two genes are involved in controlling the recessive non- shattering trait [108].…”

Comparison of the Pattern of Crop Domestication between Two Asian Beans, Azuki Bean (Vigna angularis) and Rice Bean (V. umbellata)

“…The QTLs for the domestication related traits in azuki bean were identified in three populations derived from two cross combinations 7,10 . In this review, the QTL regions that were identified in the BC 1 F 1 population 7 were compared with those in rice bean, since the QTL regions were identified in the BC 1 F 1 population in rice bean 8 . Almost all common molecular markers showed a high level of co-linearity within the same linkage group.…”

“…For 28 traits, a total of 76 QTLs were found in azuki bean 7 , whereas 69 QTLs were found in rice bean 8 . In azuki bean, the QTLs with large effect (PEV > 20%) were found on five linkage groups (LG1: seed dormancy and internode length, LG2: seed size and epicotyl and lower internode length, LG7: pod dehiscence and pod size, LG8: pod size, and LG9: twining habit) (Fig.…”