Department of Plant Pathology and Microbiology, Texas A&M University, College Station, TX 77845.
Southern Plains Agricultural Research Center, Agricultural Research Service, USDA, College Station, TX 77845.
Plant Dis. 2022 Oct;106(10):2558-2562. doi: 10.1094/PDIS-12-21-2725-SC. Epub 2022 Aug 17.
Fusarium wilt, caused by f. sp. , is a severe disease of cotton ( spp.). Strains of the wilt pathogen in the United States, such as race 1, require the presence of nematodes such as southern root-knot nematode () to cause appreciable disease. The exception is the race 4 strain of the wilt pathogen, which can attack cotton without concomitant infection by plant-parasitic nematodes and was first identified in California in 2001 and in Texas and New Mexico since 2017. The effects of the interaction between and race 1 or race 4 on wilt severity and nematode reproduction on two cultivars, Acala 44 and FM 966, and a cultivar, Pima S-4, were directly compared in growth chamber assays. All three cultivars were susceptible to Suppression of nematode reproduction by the wilt pathogen was detected only for race 4 on all three cultivars on a per plant basis but not on a per gram root tissue basis. The control, alone, and race 1 alone treatments caused no symptoms. Inoculation with race 1 and caused moderate wilt symptoms in 'Acala 44' and 'FM 966' and mild symptoms in 'Pima S-4'. However, race 4 treatment caused severe wilt in 'Pima S-4' and moderate wilt severity in 'Acala 44' and 'FM 966'. The symptom severity of 'Acala 44' and 'FM 966' further increased in the presence of . Thus, race 4 is not only capable of causing wilt in the absence of but can also interact with the nematode to further increase disease severity. Though control of wilt caused by race 1 can be achieved mainly through breeding for nematode resistance, it will be imperative to incorporate both southern root-knot nematode and race 4 resistance to effectively control the disease should race 4 expand into southern root-knot nematode-infested fields.
镰刀菌枯萎病由 f. sp. 引起，是棉花（ spp.）的一种严重疾病。美国的枯萎病病原体菌株，如 1 号品种，需要线虫如南方根结线虫（）的存在才能引起相当程度的疾病。例外的是枯萎病病原体的 4 号品种，它可以在没有植物寄生线虫感染的情况下攻击棉花，该品种于 2001 年在加利福尼亚首次被发现，并于 2017 年在德克萨斯州和新墨西哥州被发现。在生长室试验中，直接比较了 和 1 号或 4 号品种对两种棉花品种（ Acala 44 和 FM 966）和一个陆地棉品种（ Pima S-4）枯萎病严重程度和线虫繁殖的相互作用效应。所有三个品种都容易受到 仅在所有三个品种的每个植株基础上检测到枯萎病病原体对线虫繁殖的抑制作用，但在每个克根组织基础上则没有。对照、单独的枯萎病病原体和单独的 1 号品种处理均未引起症状。接种 1 号和 品种在 Acala 44 和 FM 966 中引起中度枯萎症状，在 Pima S-4 中引起轻度症状。然而，4 号品种处理在 Pima S-4 中引起严重枯萎，在 Acala 44 和 FM 966 中引起中度枯萎严重程度。在 存在的情况下， Acala 44 和 FM 966 的症状严重程度进一步增加。因此，4 号品种不仅能够在没有 存在的情况下引起枯萎病，而且还可以与线虫相互作用，进一步增加疾病严重程度。虽然通过培育线虫抗性可以主要控制由 1 号品种引起的枯萎病，但如果 4 号品种扩展到南方根结线虫侵染的田地，就必须将南方根结线虫和 4 号品种抗性结合起来，以有效控制该疾病。
