扩散型与繁殖型松材线虫数字基因表达谱对比分析

Comparative analysis of dispersal and propagative larval stages in the pinewood nematode (Bursaphelenchus xylophilus) based on a digital gene expression library

【目的】松材线虫作为林业重大外来入侵种,扩散型幼虫的形成对其传播扩散起着非常重要的作用,但扩散虫态的形成与维持机制尚未阐明。【方法】通过构建松材线虫数字基因表达谱(DGE),从滞育状态的维持、化学感受、代谢途径等方面分析松材线虫不同虫态的基因表达差异。【结果】参考松材线虫基因组数据,鉴定出2种扩散型幼虫(LⅢ,LⅣ)和繁殖型幼虫(Ln)各有11184、8533和10781个基因。相对于繁殖型虫态,大多数基因在LⅣ中下调表达,该虫态中特异上调表达的基因有化感受体基因、核受体基因以及一些代谢相关基因。推测这可能与扩散型线虫滞育状态的维持相关,并在其生理功能如化学感受和媒介/寄主互作中发挥作用。GO和Pathway富集分析显示,多数代谢相关通路在LⅣ中下调表达,而在LⅢ中的表达均活跃。【结论】以上结果与LⅣ处于不进食、总体代谢水平较低等生理状态的表型相一致。

【Aim】The formation of the dispersal larva plays an important role in the transmission and spreading of pinewood nematode( Bursaphelenchus xylophilus) which is a major alien invasive pests of forest worldwide. However,its mechanism about formation and maintenance remains unclear. 【Method】In this study,digital gene expression( DGE) libraries of two dispersal larvae [3rd instar( L_Ⅲ),and 4th instar( L_Ⅳ ) ]and of the propagative larva( Ln) were constructed to analyze the differences of gene expression of different developmental stages from aspects of maintenance of diapause,chemoreception and metabolic pathways.【Result】A total of 11184,8533,10781 genes were found for L_Ⅲ,L_Ⅳ and Lnaccording to reference genome,respectively. Compared with Ln,most of the genes in L_Ⅳ were down-regulated,and some genes,including chemoreceptor genes,nuclear hormone receptors and other metabolism related genes were up-regulated. The probable function of these genes is in regulating diapause stages,chemosensation and vector/host interaction in the dispersing larva. Gene ontology and pathway clustering analysis showed that most metabolic pathway in L_Ⅳ were down-regulated. However,genes related to metabolic pathways in L_Ⅲexpressed vigorously. 【Conclusion】This results are consistent with phenotype of the physiological status of L_Ⅳ ,which does not feed and has low level of overall metabolism.