肠道细菌对小线角木蠹蛾克服中国白蜡防御物质的影响

The role of Streltzoviella insularis larval gut bacteria in overcoming the defense substances of Fraxinus chinensis

植物受到植食性昆虫危害后将产生大量有毒性的化学防御物质提高自身抗性。为了探究小线角木蠹蛾幼虫肠道细菌在克服中国白蜡防御物质的作用,利用高效液相色谱法,明确了小线角木蠹蛾危害中国白蜡对其韧皮部中毛蕊花糖苷含量的影响;通过饲料混毒法,研究了毛蕊花糖苷对小线角木蠹蛾的作用;采用传统培养技术和16S rDNA高通量测序技术,探究抗生素清除小线角木蠹蛾幼虫肠道细菌的作用;利用活体和离体试验,对幼虫肠道细菌降解毛蕊花糖苷的能力进行研究。结果表明:(1)小线角木蠹蛾幼虫危害寄主中国白蜡导致其韧皮部中毛蕊花糖苷的含量升高。(2)毛蕊花糖苷不仅抑制幼虫正常生长,对幼虫还有毒杀作用。(3)抗生素可以将幼虫肠道内细菌完全清除。(4)发现小线角木蠹蛾幼虫肠道细菌具有降解毛蕊花糖苷的能力,其中沙雷氏菌属(Serratia sp.)和类香味菌属(Myroides sp.)降解能力最强,可降解100%毛蕊花糖苷。

Plants harmed by herbivorous insects can produce a large amount of toxic chemical defense substances to enhance their resistance.In order to explore the role of Streltzoviella insularis larval gut bacteria in overcoming the defense substances of Fraxinus chinensis,the verbascoside content of F.chinensis(infested and uninfested)phloem were determined by High-performance liquid chromatography.The effect of verbascoside on the S.insularis was studied through artificial diet mixing verbascoside.The traditional culture techniques and 16S rDNA high-throughput sequencing technology were adopted to study the effect of antibiotics on the gut bacteria of S.insularis larvae.In vivo and in vitro experiments were carried out to study the degradation effect of the larval gut bacteria on verbascoside.The results showed that:(1)The content of verbascoside in the F.chinensis phloem was increased due to the harm of S.insularis larvae;(2)Verbascoside not only inhibited the growth of larvae,but also had a toxic effect on larvae;(3)Antibiotics can completely eliminate the larval gut bacteria;(4)It was found that the gut bacteria of the S.insularis larvae can degrade verbascoside,among which Serratia sp.(G9)and Myroides sp.(G17)had the strongest effect,the degradation rate reaching to 100%.