The Screen Of The Differentially Expressed Genes And The Functional Identification Of Hsps Genes Between Bemisia Tabaci (Gennadius) B-biotype Females And Males Under Heat-shock Condition

Temperature is an important factor that determines the distribution and expansion of a species. Bemisia tabaci (Gennadius) B-biotype is one of the most destructive invasive pest of many ornamental and glasshouse crops throughout the world, and is of high heat-resistance ability. Our previous work found that B. tabaci females were more heat resistant than males. The present study was performed to give further evidences of the mechanisms underlying differential thermotolerent abilities between B. tabaci females and males by use of suppression subtractive hybridization (SSH), RNA interference (RNAi). The main results and conclusion were as follows,1. The females had higher survival rates than males after 44℃heat shock for 1h.2. Differentially expressed genes between B. tabaci females and males under heat-shock condition were screened.1) The female SSH heat-shock libraries were constructed after the females were accepted 44℃heat shock treatment for 1h. 50 Expression Sequence Tags (ESTs) were obtained after dot blot hybridization. The homology analysis with BlastP showed that 26 (52%) ESTs, which includes 16 ESTs with known function and 10 ESTs reported but unknown function, had significant matches (E-value < 10?5) to known genes in GenBank. The other 24 ESTs had no significant matches (E-value > 10?5) in GenBank. The differentially expressed ESTs were grouped into 4 categories: heat stress-related ESTs, metabolismrelated ESTs, ESTs with unclassified functions and new ESTs.2) The male SSH heat-shock libraries were constructed after the males were accepted 44℃heat-shock treatment for 1h. 83 Expression Sequence Tags (ESTs) were obtained after dot blot hybridization. The homology analysis with BlastP showed that 42 (50.6%) ESTs, which includes 31 ESTs with known function and 11 ESTs reported but unknown function, had significant matches (E-value < 10?5) to known genes in GenBank. The other 41 ESTs had no significant matches (E-value > 10?5) in GenBank. The differentially expressed ESTs were grouped into 4 categories: heat stress-related ESTs, metabolismrelated ESTs, ESTs with unclassified functions and new ESTs. Furthermore, three differentially expressed genes were further examined by real-time quantitative PCR.3) Four categories of differentially expressed genes showed different frequencies in female and male SSH libraries. The frequencies of heat stress-related ESTs (females: 30.0%; males: 33.7%), metabolism-related ESTs (females: 2.0%; males: 3.6%) and new ESTs (females: 48.0%; males: 49.4%) were less in females than males. Whereas, the frequency of unclassified function ESTs (females: 20.0%; males: 13.3%) was more in females than males.3. Hsp23, hsp70 and hsp90 mRNA expression in B. tabaci females and males under heat-shock condition were analyzed.1) Hsp23, hsp70 and hsp90 mRNA expression between females and males were similar under heat-shock condition. The Hsps mRNA expression were increased with elevated temperature, and reached a peak at a certain temperature, then decreased with elevated temperature. Hsp70 mRNA levles reached a peak at 44℃in males. However, it reached a peak at 42℃in females. Hsp23 and hsp90 mRNA expression levels reached a peak at 40℃in females and males.2) Hsp23 and hsp70 mRNA levels were higher in females than in males under heat-shock condition, but hsp70 mRNA expression level was higher in males than in females at 44℃. Hsp90 mRNA expression level showed no significant difference between females and males.4. RNAi study proved that hsp23 and hsp70 play key roles for thermotolerence in females but not males, and hsp90 showed no significant roles for thermotolerence in both females and males.1) Hsp23, hsp70 and hsp90 mRNA levels were significantly decreased in both females and males after dsRNA feeding for 3h.2) Survival rate of females was significantly decreased following 44℃heat shock for 1h after hsp23 or hsp70 dsRNA feeding for 3h. However, survival rate of males was not significantly affected.3) Survival rate of both females and males showed no significant changes following 44℃heat shock for 1h after hsp90 dsRNA feeding for 3h.Collectively, the present study showed that the heat-resistance ability in B. tabaci females was controlled by multiple differentially expressed genes. The optimum mRNA expression of heat shock genes in females promotes higher survival rate under heat-shock condition, and hsp23 and hsp27 genes play a key role during the process.