Chickpea (Cicer arietinum L.) is a major grain legume and a good source of plant-based protein. However, comprehensive knowledge of flowering time control in Cicer is lacking. In this study, we acquire high-throughput transcriptome sequencing data and analyze changes in gene expression during floral transition in the early flowering cultivar ICCV 96029, later flowering C. arietinum accessions, and two wild species, C. reticulatum and C. echinospermum. We identify Cicer orthologs of A. thaliana flowering time genes and analyze differential expression of 278 genes between four species/accessions, three tissue types, and two conditions. Our results show that the differences in gene expression between ICCV 96029 and other cultivated chickpea accessions are vernalization-dependent. In addition, we highlight the role of FTa3, an ortholog of FLOWERING LOCUS T in Arabidopsis, in the vernalization response of cultivated chickpea. A common set of differentially expressed genes was found for all comparisons between wild species and cultivars. The direction of expression change for different copies of the FT-INTERACTING PROTEIN 1 gene was variable in different comparisons, which suggests complex mechanisms of FT protein transport. Our study makes a contribution to the understanding of flowering time control in Cicer, and can provide genetic strategies to further improve this important agronomic trait.
Keywords: cultivated chickpea; differential gene expression; flowering time genes; transcriptome sequencing; vernalization response; wild Cicer.