水稻与拟禾本科根结线虫互作分子机制及抗性遗传研究进展

    Rice-Meloidogyne graminicola Interactions: Molecular Mechanisms and Genetic Basis of Host Resistance

    • 摘要: 拟禾本科根结线虫(Meloidogyne graminicola)又称水稻根结线虫(Rice root knot nematode,RRKN),是威胁全球水稻生产的重要植物寄生线虫之一。随着直播稻等节水省工栽培模式推广,稻田土壤长期处于湿润而非深水淹灌状态,为RRKN卵孵化、二龄幼虫迁移和根部侵染提供了适宜环境,RRKN发生范围和为害程度呈加重趋势。本文围绕RRKN的分布与为害、效应蛋白致病机制、水稻多层次防御反应、抗性遗传基础及抗性种质资源等方面进行综述。RRKN可通过口针向寄主细胞分泌多类效应蛋白,破坏水稻细胞壁完整性、抑制活性氧爆发、干扰PTI/ETI免疫信号、扰乱激素平衡和营养代谢,并诱导维管薄壁细胞重编程形成巨型细胞取食位点,从而完成寄生与繁殖。水稻则通过根表皮、外皮层、内皮层凯氏带及木栓质沉积等物理屏障,酚类物质、胼胝质、木质素及防御相关酶等化学防御,以及茉莉酸、水杨酸、乙烯、脱落酸等激素信号共同调控的免疫网络,多层次限制线虫侵染和发育。在遗传资源方面,抗性资源主要富集于野生稻,亚洲栽培稻中也鉴定出‘淮稻5号’‘中花11’‘华航31号’以及部分地方品种等可利用材料,为抗性基因定位、抗性机制解析和育种亲本创制提供了基础。遗传学研究已定位多个RRKN抗性相关QTL,并克隆首个主效抗性基因MG1,该基因编码典型的CC-NB-LRR蛋白,为分子标记辅助选择育种提供了重要基因资源。目前可直接用于育种的高效、稳定抗性基因仍有限,多数抗性位点易受遗传背景和环境条件影响。未来需结合多组学、效应子靶标解析、基因编辑和分子标记辅助选择,加快抗性基因挖掘与聚合利用,培育兼具广谱性、持久性和优良农艺性状的抗RRKN水稻品种,为线虫病绿色防控提供理论依据和技术途径。

       

      Abstract: Meloidogyne graminicola, also known as the rice root-knot nematode (RRKN), is one of the major plant-parasitic nematodes threatening global rice production. With the expansion of water-saving and labor-saving cultivation systems such as direct-seeded rice, paddy soils are often maintained under moist rather than deeply flooded conditions, which provides a favorable environment for RRKN egg hatching, second-stage juvenile migration, and root invasion. Consequently, both its distribution range and damage severity have shown an increasing trend. This review summarizes recent progress in RRKN distribution and damage, effector-mediated pathogenic mechanisms, multilayered rice defense responses, genetic basis of resistance, and resistant germplasm resources. RRKN secretes diverse effector proteins into host cells through its stylet, thereby compromising rice cell-wall integrity, suppressing reactive oxygen species bursts, interfering with pattern-triggered immunity/effecter-triggered immunity (PTI/ETI) signaling, disrupting hormonal balance and nutrient metabolism, and inducing the reprogramming of vascular parenchyma cells to form giant-cell feeding sites, ultimately enabling parasitism and reproduction. In response, rice restricts nematode invasion and development through multiple defense layers, including physical barriers such as the root epidermis, exodermis, endodermal Casparian strips, and suberin deposition; chemical defenses involving phenolic compounds, callose, lignin, and defense-related enzymes; and immune networks jointly regulated by jasmonic acid, salicylic acid, ethylene, abscisic acid, and other hormonal signals. In terms of genetic resources, resistance is mainly enriched in wild rice, while useful resistant materials have also been identified in Asian cultivated rice, including 'Huaidao 5', 'Zhonghua 11', 'Huahang 31', and several local varieties, providing a foundation for resistance gene mapping, mechanistic analysis, and the development of breeding parents. Genetic studies have mapped multiple RRKN resistance-associated QTLs and cloned the first major resistance gene,  MG1, which encodes a canonical CC-NB-LRR protein and represents an important genetic resource for marker-assisted selection breeding. However, efficient and stable resistance genes that can be directly used in breeding remain limited, and most resistance loci are strongly affected by genetic background and environmental conditions. Future research should integrate multi-omics approaches, effector-target analysis, genome editing, and marker-assisted selection to accelerate the discovery, pyramiding, and utilization of resistance genes, thereby developing RRKN-resistant rice varieties with broad-spectrum and durable resistance as well as desirable agronomic traits, and providing theoretical support and technical strategies for the sustainable management of nematode diseases.