Differential Expressions Of Esterase Genes In Environmental Adaptation Of The Brown Planthopper, Nilaparvata Lugen Stal

To explore the possible function and mechanisms of esterase genes in the environmental adaption of the brown planthopper, Nilaparvata lugens Stal, differential expressions of esterase EST sequences fromdifferent populations of N. lugens treated by rice varieties, nitrogen concentrations and temperatures, respectively, are analyzedusing real-time PCR in this thesis.1. EST sequence analysis of esterase genes in N. lugens24of EST sequences, highly homologous to insect esterase genes, were found with length between146bp and1324bp in N. lugens after a homology search for cDNA sequences. There are6of EST sequences encoding a polypeptide fragment containing the motif of carboxylesterase. Based on the result of homology analysis, these EST sequences belong to four subfamilies of esterase, i.e. carboxylesterases, juvenile hormone esterases, gliotactins and neuroligin.2.Effect of rice variety on expression of esterase genes in N. lugensChanges in expression level of esterase genes in adults of N. lugens populations collected from Zhejiang and Guangxi, China and Phitsanulok, Thailand were analyzed by the real-time PCR method using actin3as the reference gene, after feeding on different rice varieties inculding TN1(a insect-susceptible variety), IR64(a local variety planting widely in tropical areas), and Xiushui11(a local variety plantingwidely in China). The results show that the expression level of esterase genes is affected highly significantly with N. lugens populations, rice varieties and feeding time. A highly significant interaction on esterase gene expression between N. lugens population, rice variety and feeding time were found.3.Effect of nitrogen on expression of esterase genes in N. lugensChanges in expression level of esterase genes in adults of N. lugens populations collected from Zhejiang and Guangxi, China and Phitsanulok, Thailand were analyzed by the real-time PCR method using actin3as the reference gene, after feeding on the rice seedling treated with different nitrogen concentrations. The results show that the expression level of esterase genes is affected highly significantly with N. lugens populations, nitrogen content and feeding time. A highly significant interaction on esterase gene expression between N. lugens population, nitrogen content and feeding time were found.4. Effect of temperature on expression of esterase genes in N. lugensChanges in expression level of esterase genes in adults of N. lugens populations collected from Zhejiang and Guangxi, China and Phitsanulok, Thailand were analyzed by the real-time PCR method using actin3as the reference gene, under different temperatures of21℃,25℃and29℃, respectively. The results show that the expression level of esterase genes is affected highly significantly with N. lugens populations, temperatures and feeding time. A highly significant interaction on esterase gene expression between N. lugens population, temperatures and feeding time were found.