Cloning of allene oxide cyclase gene from Leymus mollis and analysis of its expression in wheat–Leymus chromosome addition lines

Leymus mollis (Triticeae; Poaceae) is a useful genetic resource for wheat (Triticum aestivum L.) breeding via wide hybridization to introduce its chromosomes and integrate its useful traits into wheat. Leymus mollis is highly tolerant to abiotic stresses such as drought and salinity and resistant to various diseases, but the genetic mechanisms controlling its physiological tolerance remain largely unexplored. We identified and cloned an allene oxide cyclase (AOC) gene from L. mollis that was strongly expressed under salt stress. AOC is involved in biosynthesis of jasmonic acid, an important signaling compound that mediates a wide range of adaptive responses. LmAOC cDNA consisted of 717 bp, coding for a protein with 238 amino acids that was highly similar to AOCs from barley (Hordeum vulgare) and other monocots. Subcellular localization using Nicotiana benthamiana confirmed it as a chloroplast-localized protein. LmAOC was found to be a multiple-copy gene, and that some copies were conserved and efficiently expressed in wheat-Leymus chromosome addition lines. LmAOC expression was upregulated under drought, heat, cold and wounding stresses, and by jasmonic acid and abscisic acid. Our results suggest that LmAOC plays an important role in L. mollis adaptation to abiotic stresses and it could be useful for wheat improvement.