青海省设施辣椒根结线虫病分布与病原鉴定OA

[Objective]This research aims to investigate the distribution pattern and identify the species of Meloidogyne spp.in the major agricultural regions of Qinghai Province,specifically in pepper crops,to provide a basis for the development of targeted control measures for root-knot nematode diseases in the province.[Method]In 2024,a survey was conducted to assess the occurrence of root-knot nematode(Meloidogyne spp.)disease in facility-grown pepper(Capsicum annuum L.)across major agricultural regions of Qinghai Province,China.A total of 328 suspected infected root samples were collected from pepper production green-house in 12 counties/districts across 4 prefecture-level regions.Root-knot nematodes were isolated from di-seased roots,and the morphological characteristics of 2nd-instar larvae and females,including body length,body width,tail length,and stylet length,were examined under a microscope.Genomic DNA was extracted by using the proteinase K method,and PCR amplification was performed with universal primers targeting the rDNA-ITS and 28S rDNA regions,followed by validation using species-specific primers(inc-K14-F/R,Far/Rar,Mh-F/R,and Fjar/Rjar)for four common root-knot nematode species in China.Pathogenicity was confirmed by inocula-ting nematode suspensions onto roots of six-leaf-stage healthy pepper plants,with the infection condition veri-fied through root staining approximately 40 days post-inoculation.[Result]The highest incidence of root-knot nematode disease in facility-cultivated peppers was recorded in Ping'an district and Xunhua Salar Autonomous county of Haidong city,as well as Golmud city of Haixi Mongol and Tibetan Autonomous Prefecture,with di-sease index of 70.00,55.08,and 67.69,and root-knot nematode detection rates of 75.00%,61.54%,and 73.08%,respectively.A moderately high disease incidence was observed in Huangzhong district of Xining city,with a disease index of 41.60 and a detection rate of 56.00%.In Jianzha county of Huangnan Tibetan Autono-mous Prefecture,the disease incidence was relatively low,with a disease index of 19.52 and a detection rate of 38.10%.In Minhe Hui and Tu Autonomous county and Huzhu Tu Autonomous county of Haidong city,the di-sease indices were 8.89 and 5.38,with corresponding detection rates of 27.78%and 19.23%,respectively.No root-knot nematode disease was detected in the remaining surveyed regions.Among a total of 328 suspected pepper root samples,111 were tested as positive for root-knot nematodes,resulting in an overall detection rate of 33.84%.The morphological characteristics of the isolated nematodes,including measurements,were consistent with those of M.incognita(southern root-knot nematode)and M.arenaria(peanut root-knot nematode).SCAR-specific primers for root-knot nematodes were used for PCR amplification,and 82 positive samples of M.incognita(detection rate was 25.00%)and 34 positive samples of M.arenaria(detection rate was 10.37%)were identified.Co-infection of both nematode species was observed in regions with severe infection conditions.Among the 12 molecular identification samples,the samples co-infected by M.incognita and M.in-cognita accounted for 33.33%.Neither Meloidogyne hapla(northern root-knot nematode)nor Meloidogyne javanica(java root-knot nematode)was detected.[Conclusion]Root-knot nematodes have been identified in fa-cility vegetable-growing regions of Qinghai Province,with severe infection conditions observed in certain areas,where the disease index exceeds 55.Morphological and molecular analyses confirmed that the root-knot nema-tode disease in facility-grown peppers across Qinghai Province was caused by M.incognita and M.arenaria,with M.incognita identified as the predominant species.