Improvement of copper tolerance of Arabidopsis by transgenic expression of an allene oxide cyclase gene, GhAOC1, in upland cotton (Gossypium hirsutum L.)

Allene oxide cyclase (AOC, E 5.3.99.6) is an essential enzyme in the jasmonic acid (JA) biosynthetic pathway and mediates a wide range of adaptive responses. In this report, five AOC genes (GhAOC1–GhAOC5) were cloned from upland cotton (Gossypium hirsutum L.), sequenced, and characterized. Real-time PCR analysis indicated that the transcripts of GhAOCs were abundantly expressed in roots and less in fibers, and regulated in cotton plants under methyl jasmonate (MeJA) and CuCl2 stresses. To investigate the role of GhAOC under copper stress, transgenic Arabidopsis plants overexpressing cotton GhAOC1 under control of the Cauliflower mosaic virus 35S (CaMV 35S) promoter were generated. Compared to untransformed plants, GhAOC1-overexpressing Arabidopsis thaliana plants exhibited markedly higher survival rate, shoot fresh weight, shoot dry weight, and photosynthetic efficiency, and reduced cell membrane damage and lipid peroxidation under copper stress. This study provides the first evidence that GhAOC1 plays an important role in copper stress tolerance.