Sequence and expression divergence of the AOC gene family in soybean: insights into functional diversity for stress responses.

As a signaling molecule, jasmonate plays a crucial role in orchestrating plant defense responses to a variety of biotic and abiotic stresses. Allene oxide cyclase (AOC: EC5.3.99.6) catalyzes the most important step in the jasmonate biosynthesis pathway. Six AOC genes were isolated from soybean, randomly distributed on chromosomes 1, 2, 8, 13, 18 and 19. The six AOC proteins were clustered into three groups with similarity values ranging from 55 to 95%. Real-time PCR revealed that the AOC genes have specific and complex expression patterns in multiple organs and under several stresses. Overexpression of GmAOC1 and GmAOC5 gene in transgenic tobacco, respectively enhanced tolerance to salinity and oxidative stresses. Such a large diversity within the AOC gene family might be an adaptive mechanism that developed during soybean genome evolution.