不同土著球孢白僵菌菌株对入侵昆虫西花蓟马的致病性差异与作用机制

The Western flower thrip(WFT,Franklinilla occidentalis(Pergande)),a non-native invasive species,causes substantial economic losses to vegetable and ornamental crop -s in china.The present proposed project will focus on the problemes of the causes and mechanisms of pathogenicity difference of Beauveria bassiana,isolated from china against WFT.It will investigate three aspects of the problems via micro-examination and modern techniques in molecular biology and insect pathology.The first aspect is to study the surface infection behaviour of B.bassiana with different pathogenicity against WFT.The second aspect is to study the growth and development of B.bassiana in WFT'body and cytopathogenic features.The third aspect is to detect differential expression of the enzyme with the infection WFT's cuticle of B.bassiana.The main purpose of the study is trying to understand the key causes and key factors influencing on pathogenicity difference in the processes of the surface infection behaviour,the colonazation in WFT's body and differential expression of the enzyme.The results of the study will reveal the mechanism of pathogenicity difference on different B.bassiana isolates,understand the infection mechanism of domastic B.bassiana with WFT,provide essential knowledge and reference for the research and development of microbial pesticide against WFT.

入侵我国的世界性检疫害虫西花蓟马给我国蔬菜花卉生产带来了严重的经济损失。本项目围绕"土著球孢白僵菌菌株对西花蓟马致病性差异的原因与机制"这一科学问题，采用传统的显微观察方法，结合昆虫病理学和现代分子生物学（RNA-Seq）技术，重点研究不同致病性的球孢白僵菌对西花蓟马表面侵染行为；研究其在西花蓟马体内生长发育过程及病理学，采用RNA-Seq技术研究其入侵西花蓟马表皮时酶基因差异性表达。从侵染行为和分子生物学水平上，探明球孢白僵菌表面侵染行为、在西花蓟马体内定殖行为，侵染的酶基因差异表达种类影响致病性差异的关键因素和环节。阐明不同球孢白僵菌菌株形成致病性差异的机制，解释土著球孢白僵菌对西花蓟马的侵染机制，为研发西花蓟马微生物杀虫剂提供理论依据。

入侵我国的世界性检疫害虫西花蓟马给我国蔬菜花卉生产带来了严重的经济损失。围绕“土著球孢白僵菌BbYT11（低致病性）和BbYT12（高致病性）菌株对西花蓟马致病性差异的原因与机制”这一科学问题进行研究。BbBbYT11和BbYT12菌株的分生孢子均可附着在西花蓟马体表不同区域，二者之间无明显差异。而两菌株分生孢子在萌发、穿透和体内定殖方面存在明显差异，西花蓟马接种球孢白僵菌4h后，分生孢子开始萌发并且BbYT12菌株分生孢子萌发率（82.89%）明显高于BbYT11菌株（32.84%）；8h后BbYT12菌株穿透体壁分生孢子达到82.26%，BbYT11菌株仅为12.5%；12h 后BbYT12菌株分生孢子干瘪率（57.41%）明显高于BbYT12菌株（9.9%）此时BbYT12菌株侵染的西花蓟马体内产生虫菌体；BbYT11菌株侵染西花蓟马后18h产生虫菌体，此时BbYT12侵染的西花蓟马体内产生大量的虫菌体；随后虫菌体侵染西花蓟马的脂肪体、消化道和卵巢等组织，两菌株间没有明显的差异。采用 RNA-seq技术进行分析，发现BbYT11和BbYT12菌株在可变剪切和基因表达方面存在差异，在已知基因中差异表达基因2,763 个，新基因中两菌株间共有差异表达基因 519个。针对以下7个基因Protease基因，MAPK基因，Mpl1基因， cAMPk基因，β-1,3 Glucansythase基因，Beauvericin基因和ABCtransporters基因进行荧光定量分析，Protease基因，cAMPk基因，β-1,3 Glucansythase基因，和Beauvericin基因是球孢白僵菌在西花蓟马体内定殖阶段关键酶类。球孢白僵菌可侵染西花蓟马的生殖系统，因此利用球孢白僵菌分生孢子处理西花蓟马当代蛹、成虫后，其后代的二龄、蛹与整个未成熟期期明显缩短，雌性产卵量、净增殖率、内禀增长率、平均世代周期以及周限增长率均下降阐明不同球孢白僵菌菌株形成致病性差异的机制，解释土著球孢白僵菌对西花蓟马的侵染机制，为研发西花蓟马微生物杀虫剂提供理论依据。