USDA, Agricultural Research Service, Southern Plains Agricultural Research Center, Cotton Pathology Research Unit, College Station, TX 77845, USA.
Can J Microbiol. 2011 Nov;57(11):874-86. doi: 10.1139/w11-080. Epub 2011 Oct 17.
A unique biotype of the Fusarium wilt pathogen, Fusarium oxysporum Schlecht. f.sp. vasinfectum (Atk) Sny. & Hans., found in Australia in 1993 is favored by neutral or alkaline heavy soils and does not require plant parasitic nematodes to cause disease. This makes it a threat to 4-6 million acres of USA Upland cotton ( Gossypium hirsutum L.) that is grown on heavy alkaline soil and currently is not affected by Fusarium wilt. In 2001-2002, several shiploads of live cottonseed were imported into California for dairy cattle feed. Thirteen F. oxysporum f.sp. vasinfectum isolates and four isolates of a Fusarium spp. that resembled F. oxysporum were isolated from the imported cottonseed. The isolates, designated by an AuSeed prefix, formed four vegetative compatibility groups (VCG) all of which were incompatible with tester isolates for 18 VCGs found in the USA. Isolate AuSeed14 was vegetatively compatible with the four reference isolates of Australian biotype VCG01111. Phylogenetic analyses based on EF-1α, PHO, BT, Mat1-1, and Mat1-2 gene sequences separated the 17 seed isolates into three lineages (race A, race 3, and Fusarium spp.) with AuSeed14 clustering into race 3 lineage or race A lineage depending on the genes analyzed. Indel analysis of the EF-1α gene sequences revealed a close evolutionary relationship among AuSeed14, Australian biotype reference isolates, and the four Fusarium spp. isolates. The Australian seed isolates and the four Australian biotype reference isolates caused disease with root-dip inoculation, but not with stem-puncture inoculation. Thus, they were a vascular incompetent pathotype. In contrast, USA race A lineage isolates readily colonized vascular tissue and formed a vascular competent pathotype when introduced directly into xylem vessels. The AuSeed14 isolate was as pathogenic as the Australian biotype, and it or related isolates could cause a severe Fusarium wilt problem in USA cotton fields if they become established.
1993 年在澳大利亚发现的一种独特的枯萎病菌生物型，尖孢镰刀菌萎蔫专化型（Atk）Sny. & Hans.，喜欢中性或碱性重土壤，不需要寄生线虫就能引起疾病。这对美国旱地棉花（Gossypium hirsutum L.）构成威胁，美国有 400-600 万英亩旱地棉花种植在重碱性土壤上，目前尚未受到枯萎病的影响。2001-2002 年，几批载货棉花种子进口到加利福尼亚州，用于奶牛饲料。从进口的棉花种子中分离出 13 个尖孢镰刀菌萎蔫专化型和 4 个类似于尖孢镰刀菌的镰刀菌分离物。这些分离物以 AuSeed 为前缀命名，形成了 4 个营养体亲和群（VCG），它们都与在美国发现的 18 个 VCG 的测试分离物不亲和。分离物 AuSeed14 与澳大利亚生物型 VCG01111 的 4 个参考分离物在营养体上是亲和的。基于 EF-1α、PHO、BT、Mat1-1 和 Mat1-2 基因序列的系统发育分析将 17 个种子分离物分为三个谱系（A 系、3 系和镰刀菌属），根据分析的基因，AuSeed14 聚类到 3 系或 A 系。EF-1α 基因序列的插入缺失分析表明，AuSeed14、澳大利亚生物型参考分离物和 4 个镰刀菌属分离物之间存在密切的进化关系。澳大利亚种子分离物和 4 个澳大利亚生物型参考分离物通过根浸接种引起疾病，但通过茎刺接种不引起疾病。因此，它们是一种血管不能穿透的致病型。相比之下，美国 A 系分离物容易定植于维管束组织，并在直接引入木质部时形成一种血管能穿透的致病型。AuSeed14 分离物与澳大利亚生物型一样具有致病性，如果在田间定植，它或相关分离物可能会给美国棉花田造成严重的枯萎病问题。
