Transcriptome Analysis to Identify Putative Genes Involved in Flowering Time Under Different Photoperiods in ‘Hong jin gou’ Common Bean

Abstract

Flowering time influences pod yield and quality of common bean (Phaseolus vulgaris); however, our knowledge of flowering time genes and flowering mechanisms in common bean remain limited. We performed RNA-sequencing (RNA-seq) analyses [long-day (LD) condition and short-day (SD) condition] to identify the flowering time genes and analyzed differentially expressed genes to examine their expression levels in relation to flowering time in ‘Hong Jin Gou’ common bean, a cultivar highly sensitive to photoperiod. The circadian patterns of related genes were identified using quantitative real-time polymerase chain reaction (qRT-PCR). Flowering time in ‘Hong Jin Gou’ was influenced by day length: SD conditions promoted flowering. A total of eight flowering time–related genes were identified, which were classified into photoperiod pathways. Homologs of pseudo-response regulator 5, pseudo-response regulator 7, and gigantea were more highly expressed under SD conditions than under LD conditions. Homologs of late elongated hypocotyl and timing of cab expression 1 were differentially expressed under light and dark conditions. Early flowering 3 is a key regulator of the pathway, which coordinates light and circadian clock inputs in leaves to trigger the expression of downstream genes. The present study provides critical information that could facilitate further investigations on the genetic mechanism of flowering time in common bean.