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Abstract In general, gene expression changes when cotton is infested by phytophagous insects. Screening and identification of these regulatory genes induced by cotton bollworm (Helicoverpa armigera Hübner) infestation will help us understand the molecular mechanism of the host plants resistance to insect pests. In this paper, cotton (Gossypium spp.cv. Zhong12) was as test material. The cotton plants were divided into control groups and pest stress treatment groups (including 6, 12, 24 and 48 h, pest stress treatments, respectively). The total RNA were extracted from control groups and different pest stress treatments, and the Affymetrix cotton gene chip analysis were applied to explore gene expression profiles. It was found that a total of 4 109 genes (28%) in leaves were differentially expressed after induced 6 h, 1 917 of them was up-regulated and 2 192 of them was down-regulated, respectively. After 12 h, a total of 2 605 genes(18%) were differentially expressed, 1 326 of them was up-regulated and 1 279 of them was down-regulated, separately. After 24 h, a total of 3 213 genes(22%) were differentially expressed, 1 424 of them is up-regulated and 1 789 of them was down-regulated, respectively. After 48 h, a total of 2 763 genes(19%) were differentially expressed, 1 450 of them was up-regulated and 1 313 of them is down-regulated, separately. Bioinformatics analysis revealed that function of some differentially expressed genes involved roxidative stress response, defense response, signal transduction, transcriptional regulation, flavone and flavonol biosynthesis, terpenoids synthesis and metabolism, biosynthesis of alkaloids derived from many kinds of amino acids, etc. Furthermore, some potential genes which regulate specific volatiles emission in cotton were also identified. It was found that the gene expression of farnesyl pyrophosphate synthase was regulated by circadian rhythm. Meanwhile, (+)-delta-cadinenesynthase gene expression level increased when cotton plants was infested by H. armigera. Real-time quantitative PCR results indicated that farnesyl pyrophosphate synthase gene and chalcone--flavonone isomerase gene had the highest expression level when cotton infested 6 h by H. armigera. However, farnesyl pyrophosphate synthase gene and chalcone--flavonone isomerase gene had the lowest expression level when cotton infested 48 h by H. armigera. These findings proide base studying data for defense mechanism when cotton is infested by cotton bollworm, and help us further understand the molecular regulation of terpenoids synthesis under phytophagous insects stress.
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Received: 20 February 2011
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