Quantitative trait loci (QTL) mapping for inflorescence length traits in Lablab purpureus (L.) sweet

Abstract

Lablab purpureus (L.) sweet is an ancient legume species whose immature pods serve as a vegetable in south and south-east Asia. The objective of this study is to identify quantitative trait loci (QTLs) associated with quantitative traits such as inflorescence length, peduncle length from branch to axil, peduncle length from axil to lowermost flowering node, rachis length, node number of inflorescence, rachis internode length, node order of the first inflorescence and node order of lowest inflorescence, which are key characters affecting the output of vegetable cultivars of lablab. A molecular linkage map was constructed using a F₂ population derived from the cross (Meidou2012 × Nanhui 23). The map covers 1302.4 cm with 131 loci (122 RAPD and nine morphological markers) and consist 14 linkage groups. In the F₂ population and derived F₃ families, a total of 46 QTLs explained from 8.1 to 55.0% of phenotypic variance of the traits. Of them, 16 QTLs were detectable in the same linkage regions among different generation/season combinations, and 10 QTL clusters were mapped. It suggests that, genes which control inflorescence growth were pleiotropic or coincident involving more than one trait. Thus, these QTLs may be tagged for marker assisted selection to improve yield of lablab.

Key words: Inflorescence length, lablab, linkage map, quantitative trait loci (QTLs), random amplification of polymorphic DNA (RAPD).