Molecular Characterization and Functional Analysis of Wheat TtLOX Gene Involved in Aphid Resistance

The English grain aphid (Sitobion avenaeF.) is one of the most important and destructive pests in wheat production worldwide. Lipoxygenase (LOX) is a key rate-limiting enzyme in the bio-synthesis pathway of jasmonate and methyl jasmonate in plants and animals. This enzyme is essential for plant growth and for biotic and abiotic stresses response. In this study, the TtLOX gene from wheat (Triticum turgidum) was isolated and characterized, and its conserved domains, phylogenetic relationship and subcellular localization were investigated. As a 2787-bp open reading frame (ORF) gene, TtLOX was predicted to encode a protein of 928-amino acid. TtLOX transcription was up-regulated in response to aphid feeding; the expression of TtLOX in wheat leaves was significantly higher in Lanmai, an aphid-resistant variety, than in Poland 305, an aphid-sensitive variety. In contrast, TtLOX expression was down-regulated both in individuals treated with methyl-jasmine (MeJA) and in individuals with the TtLOX gene silenced by barley stripe mosaic virus (BSMV). The aphid numbers on the MeJA treated plants and on the TtLOX gene-silenced plants were higher than that on the control plants. These results suggest that the TtLOXg ene may have potential as a target gene for controllingSitobion avenaein wheat.