Isolation, characterization and expression analysis of the genes—GhAOS, GhAOC and GhOPR3: Encoding the key enzymes involved in jasmonic acid biosynthesis in Gladiolus hybridus

Abstract

Jasmonic acid (JA) plays a regulatory role in plant development such as tuber and corm formation and their responses to environmental stresses. The action of JA in regulating plant growth and stress responses often requires the elevation of endogenous levels by de novo synthesis. Allene oxide synthase (AOS), allene oxide cyclase (AOC) and 12-oxo-phytodienoic acid reductase 3 (OPR3) are the key enzymes involved in jasmonic acid biosynthesis in plants. Here, we isolated the AOS, AOC and OPR3 genes (GhAOS, GhAOC and GhOPR3) in full length from in vitro developing corms of Gladiolus hybridus. The subcellular localization analysis indicated that both GhAOS and GhAOC were chloroplast localization proteins whereas GhOPR3 was localized within the peroxisome. Real-time quantitative PCR showed that GhAOS, GhAOC and GhOPR3 genes were expressed constitutively in all organs with different levels having a relatively higher level in corms and cormels. Additionally, we observed that MJ treatments contributed to increasing the amount of three genes, mRNA level and endogenous MJ content thus promoting corm formation and enlargement. These results revealed that GhAOS, GhAOC and GhOPR3 were genes of significant importance and their expression contributed to JA biosynthesis thus playing an important role in corm formation and enlargement.