Identification and validation of chickpea (Cicer arietinum L.) Isoflavone synthase 1 (CaIfs1) promoter conferring pathogen-induced expression

Chickpea (Cicer arietinum L.) is the third most economically important food legume in the world. Its production is severely hampered by diseases and pests. Leguminous plants generate a specific class of secondary metabolites known as isoflavonoids playing a significant role in plant-microbe interactions. The role of the Isoflavone synthase 1 (Ifs1) gene in biotic stress is long studied, however its regulation of expression and its promoter structure are yet to be explored. In this study, we have identified, cloned and characterized the promoter region of the Ifs1 gene in chickpea (PCaIfs1). Sequence analysis revealed that the nucleotide sequence of promoter of Ifs1 gene from chickpea had 42–47% with the promoter of Ifs1 gene sequence of soybean and cowpea. In-silicoanalysis of promoter sequence of Ifs1 gene identified cis regulatory motifs involved in signaling and regulation of downstream defense genes in major legumes and pathogen induced gene expression. Histochemical analysis further confirmed the activity of promoter upon induction of Sclerotium rolfsii and Fusarium oxysporum f. sp. ciceri causing collar rot and wilt disease in chickpea, respectively indicating the direct regulation of Ifs1 gene expression by pathogen inoculation.