Molecular tagging of photoperiod responsive flowering in Indian bean [Lablab purpureus (L.) Sweet]

Abstract

Photoperiod responsive flowering and growth habit might have played a key role in domestication of lablab bean (Lablab purpureus) and currently shifting its cultivation from intercropping to monoculture. Most of the landraces of lablab bean exhibit photoperiod sensitivity in flowering and indeterminate growth habit. A cross was made between GNIB21 and GP189 which are phenotypic extremes for photoperiod responsive flowering. The F1 hybrid exhibited dominant traits like indeterminate growth habit and photosensitive flowering endowed from male parent. Segregation pattern of 3:1 in F2 generation indicated monogenic recessive nature of photoperiod insensitive flowering. Bulk segregant analysis in F2 population revealed association of PvTFLy1, a locus governing determinate growth habit in lablab bean, with photoperiod responsive flowering where an amplicon of 300 bp was observed in photo sensitive GP189 while it was absent in photo insensitive variety GNIB21. Significant ÷2 test indicated coupling phase of linkage between PvTFLY1 and photoperiod responsive flowering. Linkage analysis placed PvTFLY1 at the distance of 19.23 cM from the locus governing photoperiod responsive flowering. The linkage between growth habit and photoperiod responsive flowering in common bean, soybean and Indian bean suggest that these traits may be governed by mutation or deletion of E3 (or GmPhyA3) and Dt1 homologs in Indian bean. Information available on characterized genes for photoperiod responsive flowering and determinate growth habit from common bean, soybean and other related legumes may be utilized for isolation, characterization, mapping and molecular dissection of genes involved in regulation of photoperiod responsive flowering in Indian bean.