Division of Nematology, ICAR-Indian Agricultural Research Institute, New Delhi, 110012, India.
Department of Agricultural Entomology, College of Agriculture, Uttar Banga Krishi Viswavidyalaya, Balurghat, Dakshin Dinajpur, West Bengal, India.
BMC Genomics. 2023 Dec 6;24(1):745. doi: 10.1186/s12864-023-09864-7.
Root-knot nematode Meloidogyne graminicola has emerged as a major threat in rice agroecosystems owing to climate change-induced changes in cultivation practices. Synthetic nematicides are continually being withdrawn from the nematode management toolbox because of their ill effects on the environment. A sustainable strategy would be to develop novel nematicides or resistant plants that would target nematode sensory perception, which is a key step in the host finding biology of plant-parasitic nematodes (PPNs). However, compared to the extensive literature on the free-living nematode Caenorhabditis elegans, negligible research has been performed on PPN chemosensory biology.
The present study characterizes the five chemosensory genes (Mg-odr-7, Mg-tax-4, Mg-tax-4.1, Mg-osm-9, and Mg-ocr-2) from M. graminicola that are putatively associated with nematode host-finding biology. All the genes were highly transcribed in the early life stages, and RNA interference (RNAi)-induced downregulation of each candidate gene perturbed the normal behavioural phenotypes of M. graminicola, as determined by examining the tracking pattern of juveniles on Pluronic gel medium, attraction to and penetration in rice root tip, and developmental progression in rice root. In addition, a detrimental effect on nematode chemotaxis towards different volatile and nonvolatile organic compounds and host root exudates was documented.
Our findings enrich the existing literature on PPN chemosensory biology and can supplement future research aimed at identifying a comprehensive chemosensory signal transduction pathway in PPNs.
根结线虫 Meloidogyne graminicola 由于气候变化引起的耕作方式改变，已成为水稻农业生态系统中的主要威胁。由于对环境的不良影响，合成杀线虫剂不断从线虫管理工具包中撤出。一种可持续的策略是开发针对线虫感觉感知的新型杀线虫剂或抗性植物，这是植物寄生线虫（PPN）宿主发现生物学的关键步骤。然而，与广泛的自由生活线虫 Caenorhabditis elegans 的文献相比，对 PPN 化学生物学的研究很少。
本研究从 M. graminicola 中鉴定了五个化学感觉基因（Mg-odr-7、Mg-tax-4、Mg-tax-4.1、Mg-osm-9 和 Mg-ocr-2），这些基因可能与线虫宿主发现生物学有关。所有基因在早期生命阶段都高度转录，并且每个候选基因的 RNA 干扰（RNAi）下调都会破坏 M. graminicola 的正常行为表型，这是通过检查幼虫在 Pluronic 凝胶培养基上的跟踪模式、对水稻根尖的吸引力和穿透以及在水稻根中的发育进展来确定的。此外，还记录了对线虫对不同挥发性和非挥发性有机化合物和宿主根分泌物的趋化性的有害影响。
我们的发现丰富了 PPN 化学生物学的现有文献，并可以补充未来旨在确定 PPN 中全面化学生感信号转导途径的研究。
