肿瘤坏死因子受体相关因子基因TRAF4促进烟粉虱与共生菌Portiera的共生关系

为明确肿瘤坏死因子受体相关因子（tumor necrosis factor receptor-associated factor，TRAF）基因TRAF4在烟粉虱Bemisia tabaci隐种MEAM1与含菌细胞共生菌互作中的作用，对TRAF4蛋白进行保守结构域及系统发育分析；通过实时荧光定量PCR（quantitative real-time PCR，qPCR）方法检测TRAF4在含菌细胞和整虫体内的表达量；利用RNA干扰（RNA interference，RNAi）技术抑制烟粉虱TRAF4基因表达，然后通过qPCR技术检测含菌细胞共生菌滴度、统计烟粉虱产卵量以及采用免疫荧光技术检测烟粉虱含菌细胞的自噬水平。结果表明，TRAF4蛋白含有Zinc finger和TRAF结构域，与黑腹果蝇 Drosophila melanogaster 及埃及伊蚊 Aedes aegypti的 TRAF4 蛋白聚为一支。TRAF4在含菌细胞中显著高表达。注射dsTRAF4后，TRAF4基因表达量显著下调，Portiera滴度及烟粉虱产卵量均显著下降，含菌细胞自噬水平显著升高。表明烟粉虱TRAF4不仅影响烟粉虱的产卵量，还能通过抑制含菌细胞的自噬水平维持Portiera在烟粉虱体内的滴度，对烟粉虱与Portiera共生关系的维持起到正向调控作用。

Tumor necrosis factor receptor-associated factor gene TRAF4 promotes the symbiosis between tobacco whitefly Bemisia tabaci and primary endosymbiotic bacterium Portiera

To determine the role of the tumor necrosis factor receptor-associated factor (TRAF) gene TRAF4 in the interaction between the whitefly Bemisia tabaci MEAM1 and bacteriocyte symbionts, we analyzed the conserved domain and phylogeny of the TRAF4 protein. In addition, TRAF4 expression levels in bacteriocytes and the whole body were detected using quantitative real-time PCR (qPCR). Following inhibition of TRAF4 expression in B. tabaci using RNA interference (RNAi), we measured the titers of symbionts by qPCR, counted the number of eggs, and assessed autophagy levels in bacteriocytes through immunofluorescence. The results showed that TRAF4 protein contained Zinc finger and TRAF domain and clusters with TRAF4 proteins from Drosophila melanogaster and Aedes aegypti. TRAF4 was highly expressed in the bacteriocytes. Upon injection of dsTRAF4, the expression of TRAF4 was significantly downregulated, leading to decreased titers of Portiera and reduced number of eggs laid by females. Additionally, the autophagy level of bacteriocytes was significantly increased. These results indicate that TRAF4 plays a crucial role in maintaining the titer of Portiera in B. tabaci by inhibiting autophagy in bacteriocytes, and also contributes to the interaction between B. tabaci and Portiera.