Lanubile Alessandra, Ellis Margaret L, Marocco Adriano, Munkvold Gary P
First and third authors: Department of Sustainable Crop Production, Università Cattolica del Sacro Cuore, 29122 Piacenza, Italy; first and fourth authors: Department of Plant Pathology and Microbiology, Iowa State University, Ames 50011; and second author: Department of Plant Science, California State University, Fresno 93740.
Phytopathology. 2016 Nov;106(11):1404-1412. doi: 10.1094/PHYTO-03-16-0118-R. Epub 2016 Jul 22.
The Fusarium oxysporum species complex (FOSC) is a widely distributed group of fungi that includes both pathogenic and nonpathogenic isolates. In a previous study, isolates within the FOSC collected primarily from soybean were assessed for the presence of 12 fungal effector genes. Although none of the assayed genes was significantly associated with wilt symptoms on soybean, the secreted in xylem 6 (Six6) gene was present only in three isolates, which all produced high levels of vascular wilt on soybean. In the current study, a collection of F. oxysporum isolates from soybean roots and F. oxysporum f. sp. phaseoli isolates from common bean was screened for the presence of the Six6 gene. Interestingly, all isolates for which the Six6 amplicon was generated caused wilt symptoms on soybean, and two-thirds of the isolates showed high levels of aggressiveness, indicating a positive association between the presence of the effector gene Six6 and induction of wilt symptoms. The expression profile of the Six6 gene analyzed by quantitative reverse-transcription polymerase chain reaction revealed an enhanced expression for the isolates that caused more severe wilt symptoms on soybean, as established by the greenhouse assay. These findings suggest the suitability of the Six6 gene as a possible locus for pathogenicity-based molecular diagnostics across the various formae speciales.
尖孢镰刀菌复合种（FOSC）是一类广泛分布的真菌群体，包括致病和非致病分离株。在先前的一项研究中，对主要从大豆中收集的FOSC内的分离株进行了12个真菌效应子基因的检测。尽管所检测的基因均与大豆的枯萎症状无显著关联，但木质部分泌蛋白6（Six6）基因仅在三个分离株中存在，这三个分离株均在大豆上产生了高水平的维管束枯萎病。在本研究中，对来自大豆根的尖孢镰刀菌分离株和来自菜豆的尖孢镰刀菌菜豆专化型分离株进行了Six6基因检测。有趣的是，所有产生Six6扩增子的分离株均在大豆上引起枯萎症状，并且三分之二的分离株表现出高水平的致病性，表明效应子基因Six6的存在与枯萎症状的诱导之间存在正相关。通过定量逆转录聚合酶链反应分析的Six6基因表达谱显示，如温室试验所确定的，在大豆上引起更严重枯萎症状的分离株其表达增强。这些发现表明Six6基因适合作为跨各种专化型基于致病性的分子诊断的可能位点。
