Genome-wide characterization and expression profiling of TIFY gene family in pigeonpea (Cajanus cajan (L.) Millsp.) under copper stress

Copper is a vital micronutrient for plant growth and development, but in high concentration it leads to the oxidative damage thereby initiating biosynthesis of jasmonic acid (JA). The JA signalling is mediated by various transcription factors (TFs) such as JAZ and MYC2. JAZ TFs are the negative regulators of JA signalling which are degraded in presence of JA. JAZ proteins belong to TIFY family and regulate various biological processes such as plant development, response to phytohormones, biotic and abiotic stresses. In the present study, we identified 18 TIFY family proteins in pigeonpea, which are further classified into TIFY, JAZ and ZML subfamilies. Gene expression of 12 CcTIFY genes in pigeonpea was studied under methyl jasmonate (Me-JA), JA in presence and absence of copper (Cu). Our results showed that the transcript levels of CcTIFY3, CcTIFY4, CcTIFY5, CcTIFY9 and CcTIFY16 were upregulated under Cu stress, indicating their involvement in Cu stress signalling. The presence of defense and stress responsive cis-regulatory elements in the promoter regions of these genes further confirms their involvement in response to Cu stress. Apart from feedback regulation of JAZ proteins, the expression of CcTIFY3 and CcTIFY9 was observed to be upregulated in Me-JA and JA treatment, respectively, which suggest involvement of alternative JA and Me-JA signalling.