球孢白僵菌对小菜蛾的侵染相关基因分析

Analysis of the Infection Related Genes of Beauveria bassiana against Plutella xylostella

本文研究球孢白僵菌对小菜蛾的侵染相关基因,为提高球孢白僵菌的致病力提供基因靶点,从而提高球孢白僵菌对小菜蛾的防治效果。通过室内生物测定,筛选出球孢白僵菌对小菜蛾的高毒力菌株;采用新一代Solexa高通量测序技术对纯培养的球孢白僵菌和球孢白僵菌侵染小菜蛾48 h的虫菌混合样品分别进行转录组测序,筛选差异表达基因;结合生物信息学方法分析差异表达基因涉及的基因功能及细胞通路等;应用荧光定量PCR技术验证20个基因的差异表达。转录组测序结果显示,纯培养的球孢白僵菌与侵染小菜蛾幼虫48 h的球孢白僵菌转录组对比分析共得到8383个差异表达基因,其中显著差异表达基因716个,上调基因350个,下调基因366个。本研究筛选获得的差异表达基因,特别是上调表达的基因可能与球孢白僵菌对小菜蛾的侵染有关。GO二级分类表明,DEGs被注释到26个GO term中,包括11个生物学过程,8个细胞组分和7个分子功能;Pathway分析表明共有12个Pathway,93个上调基因和61个下调基因参与了这些途径。深入分析发现,胞外丝氨酸富集蛋白、细胞壁蛋白、胞外双加氧酶、铁转运蛋白、细胞壁半乳糖抗原蛋白等在侵染过程中与毒力相关的基因均具有显著性差异表达。研究结果为阐明球孢白僵菌对小菜蛾的侵染机制提供了基础。

This study is to evaluate the synergistic effect of joint application of entomopathogenic fungi Beauveria bassiana and chemical insecticides against Plutella xylostella in laboratory, and to provide a new approach for effective control of P. xylostella. Six insecticides were evaluated for their effects on the spore germination rate, mycelial growth, sporulation rate and extracellular protease production of the strain HFW-05 in the laboratory. The results showed that low doses of chemical pesticides had no negative effects on germination rate, mycelial growth and extracellular protease activity of the conidia of the strain HFW-05, and obvious synergistic effects were observed in emamectin benzoate and chlorantraniliprole used with HFW-05. Both emamectin benzoate and chlorantraniliprole used in low-dose with HFW-05 acted more quickly against 2nd instar larvae of P. xylostella than when they were used alone. The LT50 of mixture suspensions of emamectin benzoate （4×dilution） with different concentrations of HFW-05 （1.0×10^6, 1.0×10^7, 4.0×10^7 spores/mL） against P. xylostella were 2.4 d, 2.2 d and 1.2 d, respectively, which was significantly shorter than those of the HFW-05 suspensions. The LT50 of mixture suspension of chlorantraniliprole （10×dilution） with different concentrations of HFW-05 （1.0×10^6, 1.0×10^7, 4.0×10^7 spores/mL） were all less than 1 d. Emamectin benzoate or chlorantraniliprole did not affect the muscardine cadaver rate of P. xylostella larvae infected by HFW-05. Combination of HFW-05 with low-dose emamectin benzoate or chlorantraniliprole can increase virulence of B. bassiana against P. xylostella. Therefore, it is an effective approach to control P. xylostella by combining B. bassiana HFW-05 with emamectin benzoate or chlorantraniliprole at low spray rate.