Xue Rongrong, Li Qing, Guo Ruiqing, Yan Hui, Ju Xueyang, Liao Lu, Zeng Rensen, Song Yuanyuan, Wang Jie
Key Laboratory of Ministry of Education for Genetics, Breeding and Multiple Utilization of Crops, College of Agriculture, Fujian Agriculture and Forestry University, Jinshan, Fuzhou, 350002, China.
State Key Laboratory of Ecological Pest Control for Fujian and Taiwan Crops, College of Life Sciences, Fujian Agriculture and Forestry University, Fuzhou, 350002, China.
Rice (N Y). 2023 Jan 9;16(1):1. doi: 10.1186/s12284-022-00617-w.
Plant defenses in response to chewing insects are generally regulated by jasmonic acid (JA) signaling pathway, whereas salicylic acid (SA) signaling is mainly involved in plant defense against biotrophic pathogens and piercing-sucking insects. Previous studies showed that both JA- and SA-related defenses in rice plants were triggered by the infestation of the rice striped stem borer (SSB, Chilo suppressalis), a destructive pest causing severe damage to rice production. Herbivore-associated microbes play an important role in modulating plant-insect interaction, and thus we speculate that the SSB symbiotic microbes acting as a hidden player may cause this anomalous result. The antibiotics (AB) treatment significantly depressed the performance of field-collected SSB larvae on rice plants, and reduced the quantities of bacteria around the wounds of rice stems compared to non-AB treatment. In response to mechanical wounding and oral secretions (OS) collected from non-AB treated larvae, rice plants exhibited lower levels of JA-regulated defenses, but higher levels of SA-regulated defenses compared to the treatment of OS from AB-treated larvae determined by using a combination of biochemical and molecular methods. Among seven culturable bacteria isolated from the OS of SSB larvae, Enterobacter and Acinetobacter contributed to the suppression of JA signaling-related defenses in rice plants, and axenic larvae reinoculated with these two strains displayed better performance on rice plants. Our findings demonstrate that SSB larvae exploit oral secreted bacteria to interfere with plant anti-herbivore defense and avoid fully activating the JA-regulated antiherbivore defenses of rice plants.
植物对咀嚼式昆虫的防御通常由茉莉酸（JA）信号通路调控，而水杨酸（SA）信号主要参与植物对活体营养型病原体和刺吸式昆虫的防御。先前的研究表明，水稻条纹螟虫（SSB，二化螟）的侵害会触发水稻植株中与JA和SA相关的防御反应，这种害虫对水稻生产造成严重破坏。植食性动物相关微生物在调节植物与昆虫的相互作用中起重要作用，因此我们推测，作为一个隐藏因素的SSB共生微生物可能导致了这种异常结果。与未进行抗生素（AB）处理相比，AB处理显著降低了田间采集的SSB幼虫在水稻植株上的生长表现，并减少了水稻茎伤口周围的细菌数量。通过生化和分子方法相结合测定，与来自经AB处理幼虫的口腔分泌物（OS）处理相比，水稻植株对来自未进行AB处理幼虫的机械损伤和OS表现出较低水平的JA调控防御，但SA调控防御水平较高。从SSB幼虫的OS中分离出的7种可培养细菌中，肠杆菌属和不动杆菌属有助于抑制水稻植株中与JA信号相关的防御，用这两种菌株重新接种的无菌幼虫在水稻植株上表现出更好的生长表现。我们的研究结果表明，SSB幼虫利用口腔分泌的细菌干扰植物的抗食草动物防御，避免完全激活水稻植株中JA调控的抗食草动物防御。
