Picot Adeline, Doster Mark, Islam Md-Sajedul, Callicott Kenneth, Ortega-Beltran Alejandro, Cotty Peter, Michailides Themis
Department of Plant Pathology, University of California, Davis, Kearney Agricultural Research and Extension Center, Parlier, CA 93648, USA.
Department of Plant Pathology, University of California, Davis, Kearney Agricultural Research and Extension Center, Parlier, CA 93648, USA.
Int J Food Microbiol. 2018 Jan 16;265:55-64. doi: 10.1016/j.ijfoodmicro.2017.10.023. Epub 2017 Oct 21.
To identify predominant isolates for potential use as biocontrol agents, Aspergillus flavus isolates collected from soils of almond, pistachio and fig orchard in the Central Valley of California were tested for their membership to 16 atoxigenic vegetative compatibility groups (VCGs), including YV36, the VCG to which AF36, an atoxigenic isolate commercialized in the United States as biopesticide, belongs. A surprisingly large proportion of isolates belonged to YV36 (13.3%, 7.2% and 6.6% of the total almond, pistachio and fig populations, respectively), while the percentage of isolates belonging to the other 15 VCGs ranged from 0% to 2.3%. In order to gain a better insight into the structure and diversity of atoxigenic A. flavus populations and to further identify predominant isolates, seventeen SSR markers were then used to genetically characterize AF36, the 15 type-isolates of the VCGs and 342 atoxigenic isolates of the almond population. There was considerable genetic diversity among isolates with a lack of differentiation among micro-geographical regions or years. Since isolates sharing identical SSR profiles from distinct orchards were rare, we separated them into groups of at least 3 closely-related isolates from distinct orchards that shared identical alleles for at least 15 out of the 17 loci. This led to the identification of 15 groups comprising up to 24 closely-related isolates. The group which contained the largest number of isolates were members of YV36 while five groups were also found to be members of our studied atoxigenic VCGs. These results suggest that these 15 groups, and AF36 in particular, are well adapted to various environmental conditions in California and to tree crops and, as such, are good candidates for use as biocontrol agents.
为了确定可用作生物防治剂的主要分离株，对从加利福尼亚中央山谷的杏仁、开心果和无花果果园土壤中收集的黄曲霉分离株进行了测试，以确定它们属于16个非产毒营养体亲和群（VCG），包括YV36，美国作为生物农药商业化的非产毒分离株AF36所属的VCG。令人惊讶的是，很大一部分分离株属于YV36（分别占杏仁、开心果和无花果总群体的13.3%、7.2%和6.6%），而属于其他15个VCG的分离株百分比范围为0%至2.3%。为了更好地了解非产毒黄曲霉群体的结构和多样性，并进一步确定主要分离株，随后使用17个微卫星标记对AF36、VCG的15个模式分离株和杏仁群体的342个非产毒分离株进行遗传特征分析。分离株之间存在相当大的遗传多样性，在微地理区域或年份之间缺乏分化。由于来自不同果园且具有相同微卫星谱的分离株很少见，我们将它们分成至少3个来自不同果园的密切相关分离株组，这些分离株在17个位点中的至少15个位点上具有相同的等位基因。这导致鉴定出15个组，每组最多包含24个密切相关的分离株。包含分离株数量最多的组是YV36的成员，同时还发现有5个组也是我们研究的非产毒VCG的成员。这些结果表明，这15个组，特别是AF36，非常适合加利福尼亚的各种环境条件和木本作物，因此是用作生物防治剂的良好候选者。
