Plant Pathology and Plant-Microbe Biology Section, School of Integrative Plant Science, Cornell University, Ithaca, NY 14853.
Phytopathology. 2019 May;109(5):878-886. doi: 10.1094/PHYTO-07-18-0263-R. Epub 2019 Apr 4.
Consumption of food contaminated with aflatoxin, from crops infected by , is associated with acute toxicosis, cancer, and stunted growth. Although such contamination is more common in the lower latitudes of the United States, it is unclear whether this pattern is associated with differences in the relative frequencies of aflatoxigenic individuals of . To determine whether the frequency of the aflatoxin-producing ability of increases as latitude decreases, we sampled 281 isolates from field soils in two north-south transects in the United States and tested them for aflatoxin production. We also genotyped 161 isolates using 10 microsatellite markers to assess population structure. Although the population density of was highest at lower latitudes, there was no difference in the frequency of aflatoxigenic isolates in relation to latitude. We found that the U.S. population of is subdivided into two genetically differentiated subpopulations that are not associated with the chemotype or geographic origin of the isolates. The two populations differ markedly in allelic and genotypic diversity. The less diverse population is more abundant and may represent a clonal lineage derived from the more diverse population. Overall, increased aflatoxin contamination in lower latitudes may be explained partially by differences in the population density of , not genetic population structure.
食用被黄曲霉污染的食物，这些食物来自被黄曲霉感染的作物，与急性中毒、癌症和生长迟缓有关。虽然这种污染在美国低纬度地区更为常见，但尚不清楚这种模式是否与产黄曲霉个体的相对频率存在差异。为了确定产黄曲霉能力是否随着纬度的降低而增加，我们从美国两条南北向的横断线上的田间土壤中采集了 281 个分离株，并测试了它们的黄曲霉毒素生产能力。我们还使用 10 个微卫星标记对 161 个分离株进行了基因型分析，以评估种群结构。尽管 的种群密度在低纬度地区最高，但产黄曲霉分离株的频率与纬度无关。我们发现，美国 的种群分为两个遗传分化的亚群，与分离株的化学型或地理起源无关。这两个种群在等位基因和基因型多样性方面差异显著。多样性较低的种群更为丰富，可能代表了一个来自于多样性较高种群的克隆谱系。总的来说，较低纬度地区黄曲霉污染的增加可能部分可以通过 种群密度的差异来解释，而不是遗传种群结构的差异。
