Table_4_Cellular and Transcriptional Responses of Resistant and Susceptible Cultivars of Alfalfa to the Root Lesion Nematode, Pratylenchus penetrans.XLSX

The root lesion nematode (RLN), Pratylenchus penetrans, is a migratory species that attacks a broad range of crops, including alfalfa. High levels of infection can reduce alfalfa forage yields and lead to decreased cold tolerance. Currently, there are no commercially certified varieties with RLN resistance. Little information on molecular interactions between alfalfa and P. penetrans, that would shed light on mechanisms of alfalfa resistance to RLN, is available. To advance our understanding of the host–pathogen interactions and to gain biological insights into the genetics and genomics of host resistance to RLN, we performed a comprehensive assessment of resistant and susceptible interactions of alfalfa with P. penetrans that included root penetration studies, ultrastructural observations, and global gene expression profiling of host plants and the nematode. Several gene-candidates associated with alfalfa resistance to P. penetrans and nematode parasitism genes encoding nematode effector proteins were identified for potential use in alfalfa breeding programs or development of new nematicides. We propose that preformed or constitutive defenses, such as significant accumulation of tannin-like deposits in root cells of the resistant cultivar, could be a key to nematode resistance, at least for the specific case of alfalfa-P. penetrans interaction.

根腐线虫（root lesion nematode，RLN），学名短体线虫（Pratylenchus penetrans），是一类迁移性植物寄生线虫，可侵染包括苜蓿在内的多种作物。高侵染水平会降低苜蓿的饲草产量，并削弱其耐寒性。目前尚无获批商业化种植的抗根腐线虫苜蓿品种。目前鲜有关于苜蓿与短体线虫分子互作的研究资料，此类研究可为阐明苜蓿抗根腐线虫的分子机制提供关键思路。为深化对寄主-病原互作的认知，并解析寄主抗根腐线虫的遗传与基因组学调控机制，本研究针对苜蓿与短体线虫的抗病、感病互作体系开展了全面评估，涵盖根侵入试验、超微结构观察，以及寄主植物与线虫的全局基因表达谱分析。本研究筛选得到多个与苜蓿抗短体线虫相关的候选基因，以及编码线虫效应蛋白的线虫寄生基因，上述成果有望应用于苜蓿育种项目或新型杀线虫剂的研发。我们提出，预形成或组成型防御机制（如抗病品种根系细胞中大量积累单宁样沉积物）可能是抗根腐线虫的关键途径，至少在苜蓿与短体线虫的特定互作体系中是如此。