Zhang Hang, Liu Enliang, Huang Xinzheng, Kou Junfeng, Teng Dong, Lv Beibei, Han Xiaoqiang, Zhang Yongjun
Key Laboratory of Oasis Agricultural Pest Management and Plant Protection Resources Utilization, Xinjiang Uygur Autonomous Region, College of Agriculture, Shihezi University, Shihezi, China.
State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing, China.
Front Plant Sci. 2022 Jul 13;13:898541. doi: 10.3389/fpls.2022.898541. eCollection 2022.
When attacked by insect herbivores, plants initiate sophisticated defenses mediated by complex signaling networks and usually release a blend of functional volatiles such as terpenes against infestation. The extra-long staple cotton cultivated worldwide as natural textile fiber crop is frequently exposed to a variety of herbivores, such as cotton bollworm . However, little is known about insect-induced transcriptional changes and molecular mechanisms underlying subsequent defense responses in . In the current study, transcriptome changes in infested with chewing larvae were investigated, and we identified 5,629 differentially expressed genes (DEGs) in the infested cotton leaves compared with non-infested controls. feeding triggered complex signaling networks in which almost all (88 out of 90) DEGs associated with the jasmonic acid (JA) pathway were upregulated, highlighting a central role for JA in the defense responses of against target insects. All DEGs involved in growth-related photosynthesis were downregulated, whereas most DEGs associated with defense-related transcript factors and volatile secondary metabolism were upregulated. It was noteworthy that a terpene synthase gene in the transcriptome data, , was strongly expressed in -infested leaves. The upregulation of in qPCR analysis also suggested an important role for in herbivore-induced cotton defense. assays showed that recombinant GbTPS1 catalyzed farnesyl pyrophosphate and neryl diphosphate to produce three sesquiterpenes (selinene, α-gurjunene, and β-elemene) and one monoterpene (limonene), respectively. Moreover, these catalytic products of GbTPS1 were significantly elevated in leaves after infestation, and elemene and limonene had repellent effects on larvae in a dual-choice bioassay and increased larval mortality in a no-choice bioassay. These findings provide a valuable insight into understanding the transcriptional changes reprogramming herbivore-induced sesquiterpene biosynthesis in infested by , which help elucidate the molecular mechanisms underlying plant defense against insect pests.
当受到昆虫食草动物攻击时，植物会启动由复杂信号网络介导的精密防御机制，通常会释放出一系列功能性挥发物，如萜类化合物来抵御侵害。作为天然纺织纤维作物在全球种植的超长绒棉经常受到多种食草动物的侵害，比如棉铃虫。然而，关于昆虫诱导的转录变化以及随后超长绒棉防御反应的分子机制，我们所知甚少。在本研究中，我们调查了被咀嚼式幼虫侵害的超长绒棉的转录组变化，并且与未受侵害的对照组相比，我们在受侵害的棉花叶片中鉴定出了5629个差异表达基因（DEGs）。棉铃虫取食触发了复杂的信号网络，其中几乎所有（90个中的88个）与茉莉酸（JA）途径相关的差异表达基因都上调了，这突出了茉莉酸在超长绒棉对目标昆虫防御反应中的核心作用。所有参与与生长相关的光合作用的差异表达基因都下调了，而大多数与防御相关的转录因子和挥发性次生代谢相关的差异表达基因都上调了。值得注意的是，转录组数据中的一个萜类合酶基因，GbTPS1，在被棉铃虫侵害的超长绒棉叶片中强烈表达。在qPCR分析中GbTPS1的上调也表明其在食草动物诱导的棉花防御中起重要作用。酶活性测定表明，重组GbTPS1分别催化法呢基焦磷酸和香叶基二磷酸生成三种倍半萜（芹子烯、α-古芸烯和β-榄香烯）和一种单萜（柠檬烯）。此外，在棉铃虫侵害后，超长绒棉叶片中GbTPS1的这些催化产物显著增加，并且在双选生物测定中榄香烯和柠檬烯对棉铃虫幼虫有驱避作用，在无选生物测定中增加了幼虫死亡率。这些发现为理解被棉铃虫侵害的超长绒棉中食草动物诱导的倍半萜生物合成的转录变化提供了有价值的见解，这有助于阐明植物防御害虫的分子机制。
