Arias M M Díaz, Munkvold G P, Ellis M L, Leandro L F S
Department of Plant Pathology and Microbiology, Iowa State University, Ames.
Plant Dis. 2013 Dec;97(12):1557-1562. doi: 10.1094/PDIS-11-12-1059-RE.
A 3-year survey was conducted in Iowa to characterize the distribution and frequency of species of Fusarium associated with soybean roots. Ten plants were collected from each of 40 to 57 fields each year at V2 to V5 and R3 to R4 soybean growth stages. Fusarium colonies were isolated from symptomatic and symptomless roots and identified to species based on cultural and morphological characteristics. Species identification was confirmed by amplification and sequencing of the translation elongation factor (EF1-α) gene. Fifteen species were identified; Fusarium oxysporum was isolated most frequently, accounting for more than 30% of all isolates. F. acuminatum, F. graminearum, and F. solani were also among the most frequent and widespread species. Eleven other species were recovered from few fields, accounting for less than 10% of all isolates in a given year. No consistent trends were observed in geographic distribution of species. Variability in species frequency was found between soybean growth stages. Fusarium oxysporum was recovered at higher frequency during vegetative stages (40%) than reproductive stages (22%). Conversely, species such as F. acuminatum, F. graminearum, and F. solani were recovered more often from reproductive-stage plants. No significant differences in species composition were observed among fields differing in tillage practices and row spacing.
在爱荷华州开展了一项为期3年的调查，以描述与大豆根系相关的镰刀菌物种的分布和频率。每年在大豆生长阶段V2至V5和R3至R4期间，从40至57块田地中的每块田地采集10株植株。从有症状和无症状的根系中分离出镰刀菌菌落，并根据培养和形态特征鉴定到物种。通过翻译延伸因子（EF1-α）基因的扩增和测序确认物种鉴定结果。共鉴定出15个物种；尖孢镰刀菌的分离频率最高，占所有分离株的30%以上。锐顶镰刀菌、禾谷镰刀菌和茄病镰刀菌也是最常见和分布最广的物种之一。从少数田地中还分离出其他11个物种，在某一年中占所有分离株的比例不到10%。未观察到物种地理分布的一致趋势。在大豆生长阶段之间发现了物种频率的差异。尖孢镰刀菌在营养生长阶段（40%）的分离频率高于生殖生长阶段（22%）。相反，锐顶镰刀菌、禾谷镰刀菌和茄病镰刀菌等物种在生殖生长阶段植株中的分离频率更高。在耕作方式和行距不同的田地之间，未观察到物种组成的显著差异。
