Identification of CaMATE genes family in pepper and functional characterization of CaMATE27 in capsaicin accumulation.

The Multidrug and Toxic Compound Extrusion (MATE) gene family are known not only for transport activities but also for regulating response to environmental stresses. Capsaicin (CAP) is an important secondary metabolite in chili peppers. Herein, we identified 52 CaMATE genes in the pepper genome database. The CaMATE proteins exhibiting Polysacc_synt_C and transmembrane domain, evolutionary distributed into four subfamilies and spread across 11 pepper chromosomes. Gene ontology (GO) analysis indicated CaMATE proteins are engaged in drug and ion transport activities. Various hormonal and stress-responsive cis-elements were recorded in the upstream region of CaMATE genes. The microarray analysis showed the varied expression of CaMATE genes in various fruit tissues, including whole fruit, placenta, pericarp and seeds. The qRT-PCR expression analysis displayed the higher expression of CaMATE27 in the placenta tissue at different days post anthesis (DPA). Virus-induced gene silencing (VIGS) of CaMATE27 reduced the CAP and dihydrocapsaicin (DhCAP) content in the septum and placenta tissue. Our findings highlighted the important role of CaMATE genes in CAP transport and accumulation.