Proline synthesis and catabolism-related genes synergistically regulate proline accumulation in response to abiotic stresses in grapevines

Abstract

Proline is an important osmotic regulator for plants under abiotic stresses. Proline accumulation is regulated by various enzymes, while genes encoding these enzymes have not been fully investigated in grapevines. In this study, we identified four proline biosynthesis-related genes (P5CS1, P5CS2, P5CR and OAT) and two proline catabolism-related genes (PDH and P5CDH) from grapevines, and conducted bioinformatics analysis including protein characteristic, gene structure, phylogenetic relationship and cis-acting element of promoters. Promoter analysis found that cis-acting elements related to stress and phytohormone responsiveness were present in the promoters of these genes. Tissue-specific expression analysis of these genes indicated that P5CS2, OAT and PDH expressed highly in flower, and P5CS1, P5CR and P5CDH had highest expression levels in tendril, berry and leaf respectively. Expression patterns of these genes under abiotic stresses revealed that P5CS1, OAT and PDH could be significantly induced by salt, dehydration, PEG and H2O2 treatments, and P5CDH was significantly suppressed under these stress treatments. By measuring proline accumulation in grapevines, we found that proline content dramatically increased after treatments of salt, dehydration, PEG and H2O2. Our results revealed the molecular responses (especially P5CS1, OAT, PDH and P5CDH) in the proline metabolism pathway to osmotic and oxidative stresses in grapevines, demonstrating that proline synthesis and proline catabolism synergistically regulate proline accumulation in response to abiotic stresses.