烟粉虱模式识别受体βGRPs的先天免疫应答

Innate immune response of the pattern recognition receptor βGRPs in Bemisia tabaci(Hemiptera: Aleyrodidae)

为探索烟粉虱的β-1,3-葡聚糖识别蛋白（BtβGRP）在烟粉虱先天免疫过程中的重要作用,对烟粉虱中鉴定的3个BtβGRPs基因编码的蛋白质进行结构分析,并与其它物种的23个同源蛋白进行系统进化分析,同时通过实时荧光定量PCR（quantitative real-time PCR,q RT-PCR）检测分析球孢白僵菌侵染烟粉虱不同虫态不同时间点后BtβGRPs的时间表达模式。结果显示：经鉴定3个BtβGRPs蛋白序列均含有βGRP家族特有的保守性结构域,即糖苷水解酶活性结构域;且3个BtβGRPs独自聚在进化树的一支上,可能参与烟粉虱特有的级联路径;3个BtβGRPs基因在不同虫态和不同诱导时间点与对照相比,除BtβGRP3在卵期未表达外,均有上调表达趋势,但诱导程度不同;成虫诱导24~36 h后达到峰值,比卵和若虫稍晚,可能是由于烟粉虱成虫体表有白色蜡粉等物质,延迟了球孢白僵菌对虫体的侵染。研究表明3个BtβGRPs蛋白可能参与了烟粉虱对真菌侵染的免疫反应,有可能成为烟粉虱生防的新靶标。

In order to understand the roles of β-1,3-glucan recognition protein（ βGRP） in the signal pathways of innate immune reaction in Bemisia tabaci, three βGRPs identified in B. tabaci were characterized by using protein structure analysis and phylogenetic analysis with homologous genes of 23 other insects. The different developmental stages of B. tabaci were infected by the fungus Beauveria bassiana and subsequently the expression of βGRP genes was analyzed by quantitative real-time PCR. The protein structure analysis showed that three sequences had the unique structure of βGRP family which contained conserved domains-glycoside hydrolase activity domain. Three BtβGRPs formed a clade specific to B. tabaci that would be involved in a unique cascade path of B. tabaci. Transcriptional levels of threeβGRPs genes in B. tabaci were up-regulated at different stages and different time points compared to the control,except BtβGRP3（ not expressed in the egg stage）,but the degree of infection was different. The relative expression quantity peaked in adults at 24- 36 h,later than in eggs and nymphs,probably due to wax and other substances on the surface of B. tabaci,which delayed the infection of B. bassiana. In conclusion,the three BtβGRPs might participate in the innate immune responses to the infection of the fungus in B. tabaci,and could be a novel target for biocontrol of B. tabaci.