The Characteristics Of Temperature-induced Dna Methylation And The Functional Identification Of Dnmt1 Gene In Bemisia Tabaci Under Temperature Stress Condition

Bemisia tabaci Mediterranean(MED) cryptic species had been rapidly spreading to most parts of China s ince it invaded into China. The whitefly has strong ecological adaptability s ince it can successfully adapt to different geographical environments in a short time period. The objective was to reveal the temperature adaptability mechanism of B. tabaci based on epigenetics.. In the present study, firstly, an invasive species B. tabaci MED and a native species B. tabaci AsiaII3 were choosen to study the difference of temperature tolerance among different generations or between sexes under different stress temperature treatments; secondly, the relationship between DNA methylation and thermotolerence were investigated using F-MSAP technique; lastly,the Dnmt1 genes of the three cryptic specieseswere cloned and the temperature tolerance function was identified by RNAi technology. The main results and conclusions were as follows, 1. Temperature-induced tolerance of B. tabaci can be inherited:(1) Temperature-induced tolerance of B. tabaci can be inherited from the 1st to 3rd generations, and the tolerance induced by high temperature was greater than that of low temperature, and the insects showed higher heat tolerance rather than cold resistance. And the females were higher temperature tolerant than males.(2) MED had higher tolerance ability than that of AsiaII3 under high temperature condition.(3) Temperature tolerance of B. tabaci were significantly different under different conditions. 2. The temperature tolerance was closely associated with DNA methylation in B. tabaci.(1) The methylation levels of MED were lower than that of AsiaII3 in 1-3 generations under different temperature stress, when compared to control, and the methylation levels was higher in MED, but was lower in AsiaII3.(2) The methylation levels were significant different for both MED and As iaII3 under different developmental stages.(3) The methylation levels of the eggs was significant higher than other stages under temperature stress. 3. In this study, the three full c DNA sequences of Dnmt1 gene were obtained from the MED, MEAM1 and AsiaII3, respectively. The amino acids sequence, structure and phylogenetic was analyzed, respectively. In addition, it was indicated that Dnmt1 gene played a key role in thermotolerence in B. tabaci.It was concluded that, temperature-induced tolerance of B. tabaci was heritable, and the temperature tolerance was closely related with DNA methylation, in which Dnmt1 play an important role in thermotolerence in B. tabaci.