First report of Meloidogyne incognita infecting white Pitahaya plants

Abstract In July 2020, during a survey carried out in a small farm located in Laranjal Paulista, state of São Paulo (Brazil), more than 20 white pitahaya plants [Hylocereus undatus (Haw.) Britton and Rose (syn. Selenicereus undatus (Haw.) D.R. Hunt] were found with stunting symptoms and showing chlorotic-yellowish stems, some of them already decaying. Roots exhibited numerous galls, indicating Meloidogyne sp. infection. Nematodes were recovered from 200 cm³ and 7 g of roots: 1.7 Meloidogyne juveniles (J2) per cm³ of soil and 954 eggs + J2 per g of roots were found. The perineal pattern of 10 females pointed to M. incognita. Additionally, esterase phenotype was obtained through isozyme electrophoresis, using another 10 females, which identified M. incognita. To our knowledge, this is the first report of M. incognita infesting pitahaya plants (Hylocereus spp.) and, based on our results, M. incognita could be a potential threat to the crop.

摘要 2020年7月，在巴西圣保罗州拉兰雅尔保利斯塔（Laranjal Paulista）一处小型农场开展的调查中，研究人员发现超过20株白肉火龙果植株[量天尺（Hylocereus undatus (Haw.) Britton and Rose，异名：Selenicereus undatus (Haw.) D.R. Hunt）]出现矮化症状，茎部呈褪绿黄化状态，部分植株已腐烂，其根系可见大量根结，提示存在根结线虫属（Meloidogyne sp.）侵染。研究人员从200 cm³土壤及7 g根系样品中分离得到线虫：每立方厘米土壤中检出1.7条根结线虫二龄幼虫（J2），每克根系中检出954个卵及二龄幼虫；对10头雌虫的会阴花纹进行观察，鉴定为南方根结线虫（Meloidogyne incognita）。此外，通过同工酶电泳技术对另外10头雌虫进行酯酶表型分析，同样鉴定为南方根结线虫。据我们所知，本研究为首次报道南方根结线虫侵染量天尺属（Hylocereus spp.）火龙果植株，研究结果表明南方根结线虫可能对该作物构成潜在威胁。