3种橘园杂草在柑橘木虱传播黄龙病中的作用与机制

Citrus huanglongbing (HLB) is a destructive bacterial disease, which is spread by the vector-Asian citrus psyllid (ACP) effectively. Its catastrophe mechanism is still unclear. Though the host range of ACP is strict, some non-host weeds let ACP adult feed on and long - term survive, and HLB bacterium was tested out. It showed that weed had certain effect to ACP and HLB spread. In our project, 3 weeds would be chosen to study on effect of them on ACP and HLB spread, with the host plant as the control. It include: (1) Effect of weed on ACP survival time, fertility and population development, (2) Way and ability of HLB spread from or to weed, (3) Effect of weed on HLB bacterium survival and multiplication, (4) Effect of HLB bacterium on choice and adaption of ACP to weed, (5) Ativity change of digestive and resistance enzyme of ACP on weed, (6) Weed secondary compounds related to survival and multiplication of ACP and HLB bacterium. From these results, the effect of the weeds on ACP and HLB spread and its mechanism would be analyzed, which would be help to probed its molecular mechanism, clarify the catastrophe mechanism and transmission route of HLB and provide references to research on the interaction mechanism between pathogenic bacteria, insect vector and plant.

柑橘黄龙病是毁灭性的细菌病害，其灾变机制仍未厘清。它的媒介昆虫－柑橘木虱的寄主仅限于芸香科植物，目前在研究和防治上也专注于此。我们发现木虱成虫可选择栖息在一些非芸香科的杂草上，虽不能完成世代但可长期存活，并在杂草上检测出黄龙病菌，显示这些杂草可能有利于木虱传播黄龙病。本项目拟在前期工作基础上，选择橘园常见杂草龙葵、菟丝子和藿香蓟，以柑橘为对照，通过研究：(1) 杂草对木虱个体存活和种群发展的影响；（2）病菌传入、传出杂草的能力和方式；（3）杂草对木虱体内病菌存活与增殖的影响；(4) 病菌对木虱选择和适应杂草的影响；（5）杂草上木虱相关酶的活性变化；（6）与杂草影响木虱和病菌生存、增殖相关的植物化学信息、营养或限制因子，探索杂草在柑橘木虱传播黄龙病中的作用与机制，为今后深入研究其分子机理、全面厘清黄龙病的传播途径和灾变机制提供依据，也为细菌-害虫-植物互作机理的研究提供参考。

黄龙病是全球发生的毁灭性柑橘病害，柑橘木虱是其主要传播媒介。通常认为，该虫的寄主植物限于芸香科内的植物。但近期报道柑橘木虱对一些非芸香科的杂草有较高的适应性，如我们在野外发现该虫可栖息于龙葵上，并在其叶中检出黄龙病菌，类似的橘园常见杂草极有可能增加该虫在逆境中的生存能力和传播黄龙病的风险。本项目在前期工作基础上，选择常见杂草龙葵、藿香蓟、假臭草和菟丝子等，比较深入和系统研究了这些非寄主植物在柑橘木虱和黄龙病扩散与再生猖獗中的可能作用与机理。.主要研内容内容和结果如下：.1)柑橘木虱对各种杂草的适应性各有特点：对龙葵的选择性较强，在其上的存活期达41 d，且雌虫显著高于雄虫；对藿香蓟的选择率开始较低，但随时间推移，选择率显著增加，在其上存活期可达48 d；对假臭草选择率低，存活期也短，仅11 d；若虫在3种杂草上均不能羽化成虫。木虱在寄生于柑橘上的菟丝子羽化率高、存活期长，在寄生于杂草上的菟丝子羽化率低、存活期短。与杂草在本地共处的时间越长，木虱对杂草的适应性似乎越强。.2)在秋季，黄龙病菌含量在杂草上取食的木虱体内均显著增加，但在柑橘上取食的木虱体内无显著变化；在春季则刚好相反。显示病菌在木虱对逆境的适应及季节性转移上有一定的协调作用。.3)利用代谢组学技术，测试杂草代谢物：健康木虱取食胁迫后，杂草的差异代谢物分别为63、37、52种；而携菌木虱取食后，其差异代谢物分别为40、51、64种。植物种类不同，化合物差异非常大。通过蛋白组学和16S肠道微生物测序，木虱取食杂草后，其体内蛋白质和肠道微生物均有显著变化。.4)杂草对农药防效有一定的干扰作用；杂草对木虱天敌植绥螨也有相应影响。.综上所述，一些非寄主植物可能影响到柑橘木虱、黄龙病与寄主植物的共处，增加木虱再生猖獗和传播黄龙病的风险。调整景观生态、注重果园植物的配置、保护和引入天敌，将有利于黄龙病的可持续控制。.