Jelinski Nicolas A, Broz Karen, Jonkers Wilfried, Ma Li-Jun, Kistler H Corby
First author: Department of Soil, Water and Climate, University of Minnesota-Twin Cities, 1991 Upper Buford Circle, Saint Paul 55108; second and fifth authors: U.S. Department of Agriculture-Agricultural Research Service, Cereal Disease Laboratory, 1551 Lindig Street, University of Minnesota-Twin Cities, Saint Paul 55108; third author: Bejo Zaden BV, Trambaan 1, 1749CZ Warmenhuizen, The Netherlands; and fourth author: Department of Biochemistry and Molecular Biology, University of Massachusetts-Amherst, Amherst 01003.
Phytopathology. 2017 Jul;107(7):842-851. doi: 10.1094/PHYTO-12-16-0437-R. Epub 2017 May 4.
Seventy-four Fusarium oxysporum soil isolates were assayed for known effector genes present in an F. oxysporum f. sp. lycopersici race 3 tomato wilt strain (FOL MN-25) obtained from the same fields in Manatee County, Florida. Based on the presence or absence of these genes, four haplotypes were defined, two of which represented 96% of the surveyed isolates. These two most common effector haplotypes contained either all or none of the assayed race 3 effector genes. We hypothesized that soil isolates with all surveyed effector genes, similar to FOL MN-25, would be pathogenic toward tomato, whereas isolates lacking all effectors would be nonpathogenic. However, inoculation experiments revealed that presence of the effector genes alone was not sufficient to ensure pathogenicity on tomato. Interestingly, a nonpathogenic isolate containing the full suite of unmutated effector genes (FOS 4-4) appears to have undergone a chromosomal rearrangement yet remains vegetatively compatible with FOL MN-25. These observations confirm the highly dynamic nature of the F. oxysporum genome and support the conclusion that pathogenesis among free-living populations of F. oxysporum is a complex process. Therefore, the presence of effector genes alone may not be an accurate predictor of pathogenicity among soil isolates of F. oxysporum.
对从佛罗里达州马纳蒂县同一田地获得的74株尖孢镰刀菌土壤分离株，检测了尖孢镰刀菌番茄枯萎病3号生理小种菌株（FOL MN - 25）中存在的已知效应子基因。根据这些基因的有无，定义了四种单倍型，其中两种占所调查分离株的96%。这两种最常见的效应子单倍型要么包含所有检测的3号生理小种效应子基因，要么都不包含。我们假设，与FOL MN - 25相似，含有所有检测效应子基因的土壤分离株对番茄具有致病性，而缺乏所有效应子的分离株则无致病性。然而，接种实验表明，仅效应子基因的存在并不足以确保对番茄的致病性。有趣的是，一个含有全套未突变效应子基因的无致病性分离株（FOS 4 - 4）似乎经历了染色体重排，但仍与FOL MN - 25营养体亲和。这些观察结果证实了尖孢镰刀菌基因组的高度动态性，并支持了尖孢镰刀菌自由生活群体中的致病机制是一个复杂过程的结论。因此，仅效应子基因的存在可能不是尖孢镰刀菌土壤分离株致病性的准确预测指标。
