Rickettsia influences thermotolerance in the whitefly Bemisia tabaci B biotype  

作　　者：Marina Brumin Svetlana Kontsedalov Murad Ghanim 

机构地区：[1]Department of Entomology, Institute of Plant Protection, the Volcani Center, Bet Dagan, Israel

出　　处：《Insect Science》2011年第1期57-66,共10页昆虫科学（英文版）

基　　金：This research was supported by Research Grant No. IS- 4062-07 from the United States-Israel Binational Agricultural Research and Development Fund （BARD） to MG, and supported in part by the Israel Science Foundation Research Grant No. 884/07 to MG. This is contribution 507/10 from the ARO, The Volcani Center, Bet Dagan, Is- rael. We thank two anonymous reviewers who gave valuable comments for improving the manuscript.

摘　　要：The whitefly Bemisia tabaci harbors Portiera aleyrodidarum, an obligatory symbiotic bacterium, as well as several secondary symbionts, including Rickettsia, Hamiltonella, Wolbachia, Arsenophonus, Cardinium and Fritschea, the function of which is unknown. In Israel, Rickettsia is found in both the B and Q ofB. tabaci biotypes, and while all other secondary symbionts are located in the bacteriomes, Rickettsia can occupy most of the body cavity of the insect. We tested whether Rickettsia influences the biology of B. tabaci and found that exposing a Rickettsia-containing population to increasing temperatures significantly increases its tolerance to heat shock that reached 40~C, compared to a Rickettsia-free population. This increase in tolerance to heat shock was not associated with specific induction of heat-shock protein gene expression; however, it was associated with reduction in Rickettsia numbers as was assessed by quantitative real-time polymerase chain reaction and fluorescence in situ hybridization analyses. To assess the causes for thermotolerance when Rickettsia is reduced, we tested whether its presence is associated with the induction of genes required for thermotolerance. We found that under normal 25℃ rearing temperature, genes associated with response to stress such as cytoskeleton genes are induced in the Rickettsia-containing population. Thus, the presence of Rickettsia in B. tabaci under normal conditions induces the expression of genes required for thermotolerance that under high temperatures indirectly lead to this tolerance.The whitefly Bemisia tabaci harbors Portiera aleyrodidarum, an obligatory symbiotic bacterium, as well as several secondary symbionts, including Rickettsia, Hamiltonella, Wolbachia, Arsenophonus, Cardinium and Fritschea, the function of which is unknown. In Israel, Rickettsia is found in both the B and Q ofB. tabaci biotypes, and while all other secondary symbionts are located in the bacteriomes, Rickettsia can occupy most of the body cavity of the insect. We tested whether Rickettsia influences the biology of B. tabaci and found that exposing a Rickettsia-containing population to increasing temperatures significantly increases its tolerance to heat shock that reached 40~C, compared to a Rickettsia-free population. This increase in tolerance to heat shock was not associated with specific induction of heat-shock protein gene expression; however, it was associated with reduction in Rickettsia numbers as was assessed by quantitative real-time polymerase chain reaction and fluorescence in situ hybridization analyses. To assess the causes for thermotolerance when Rickettsia is reduced, we tested whether its presence is associated with the induction of genes required for thermotolerance. We found that under normal 25℃ rearing temperature, genes associated with response to stress such as cytoskeleton genes are induced in the Rickettsia-containing population. Thus, the presence of Rickettsia in B. tabaci under normal conditions induces the expression of genes required for thermotolerance that under high temperatures indirectly lead to this tolerance.

关 键 词：CYTOSKELETON gene expression heat shock SYMBIONT 

分 类 号：S945.46[农业科学—水产养殖] S433.3[农业科学—水产科学]