Weaver Mark A, Park Lilly C, Brewer Michael J, Grodowitz Michael J, Abbas Hamed K
ARS, National Biological Control Laboratory, 59 Lee Road, Stoneville, MS, 38776, USA.
Entomology Program, Texas A&M AgriLife Research & Extension Center, 10345 State Hwy 44, Corpus Christi, TX, 78406, USA.
Mycotoxin Res. 2025 Feb;41(1):267-276. doi: 10.1007/s12550-025-00581-6. Epub 2025 Jan 14.
Aflatoxin contamination of corn can occur when developing kernels are infected by the plant pathogen Aspergillus flavus. One route of infection is from airborne conidia. We executed a series of experiments within the corn canopy during two growing seasons and in two states to document the abundance and dynamics of the airborne A. flavus population. We did not observe any significant diurnal changes in the conidial density (p = 0.171) or any effect of sampler height (p = 0.882) within the canopy. Significant changes (p < 0.001) were noted during the season, with a trend towards increased airborne populations with later stages of corn development and more than a 20-fold increase from July to August. The median aflatoxigenicity of airborne isolates from a corn canopy in Texas was about 50 times higher than the corresponding population in Mississippi. It was also noteworthy that highly aflatoxigenic, weakly sporulating S-morphotypes accounted for 14-30% of the airborne isolates in Mississippi at a site with historically rare abundance of S-morphotypes. The genetic diversity was high among the 140 analyzed airborne isolates, with 76 unique haplotypes identified and 55 haplotypes occurring only in 1 isolate. Even in the context of this highly diverse population, a haplotype matching that of a commercial biocontrol strain was found in 13 of the 70 isolates from Mississippi and 1 of the 70 isolates from Texas. The airborne A. flavus population is genetically diverse (Shannon's index = 1.4 to 1.6), similar to grain samples in other surveys, and much less aflatoxigenic in Mississippi than in Texas.
当发育中的玉米粒被植物病原体黄曲霉感染时，玉米就会受到黄曲霉毒素污染。一种感染途径是通过空气传播的分生孢子。我们在两个生长季节和两个州的玉米冠层内进行了一系列实验，以记录空气传播的黄曲霉菌落的丰度和动态。我们没有观察到分生孢子密度有任何显著的昼夜变化（p = 0.171），也没有观察到冠层内采样高度的任何影响（p = 0.882）。在季节期间观察到显著变化（p < 0.001），随着玉米发育后期，空气传播的菌量有增加趋势，从7月到8月增加了20多倍。得克萨斯州玉米冠层空气传播分离株的黄曲霉毒素产毒中位数比密西西比州相应群体高约50倍。同样值得注意的是，在一个历史上S形态型数量稀少的地点，高度产黄曲霉毒素、弱产孢的S形态型占密西西比州空气传播分离株的14 - 30%。在分析的140株空气传播分离株中，遗传多样性很高，鉴定出76个独特的单倍型，55个单倍型仅出现在1个分离株中。即使在这个高度多样化的群体中，在密西西比州的70个分离株中有13个、得克萨斯州的70个分离株中有1个发现了与商业生物防治菌株匹配的单倍型。空气传播的黄曲霉菌落遗传多样（香农指数 = 1.4至1.6），与其他调查中的谷物样本相似，并且在密西西比州的产黄曲霉毒素能力比在得克萨斯州低得多。
