Department of Entomology, Texas A & M University, College Station, Texas, United States of America.
PLoS One. 2013 Jun 11;8(6):e66049. doi: 10.1371/journal.pone.0066049. Print 2013.
Studies of fungi in upland cotton (Gossypium hirsutum) cultivated in the United States have largely focused on monitoring and controlling plant pathogens. Given increasing interest in asymptomatic fungal endophytes as potential biological control agents, surveys are needed to better characterize their diversity, distribution patterns and possible applications in integrated pest management. We sampled multiple varieties of cotton in Texas, USA and tested for temporal and spatial variation in fungal endophyte diversity and community composition, as well as for differences associated with organic and conventional farming practices. Fungal isolates were identified by morphological and DNA identification methods. We found members of the genera Alternaria, Colletotrichum and Phomopsis, previously isolated as endophytes from other plant species. Other recovered species such as Drechslerella dactyloides (formerly Arthrobotrys dactyloides) and Exserohilum rostratum have not, to our knowledge, been previously reported as endophytes in cotton. We also isolated many latent pathogens, but some species such as Alternaria tennuissima, Epicoccum nigrum, Acremonium alternatum, Cladosporium cladosporioides, Chaetomium globosum and Paecilomyces sp., are known to be antagonists against plant pathogens, insects and nematode pests. We found no differences in endophyte species richness or diversity among different cotton varieties, but did detect differences over time and in different plant tissues. No consistent patterns of community similarity associated with variety, region, farming practice, time of the season or tissue type were observed regardless of the ecological community similarity measurements used. Results indicated that local fungal endophyte communities may be affected by both time of the year and plant tissue, but the specific community composition varies across sites. In addition to providing insights into fungal endophyte community structure, our survey provides candidates for further evaluation as potential management tools against a variety of pests and diseases when present as endophytes in cotton and other plants.
美国旱地棉（Gossypium hirsutum）真菌的研究主要集中在监测和控制植物病原体上。鉴于人们对无症状真菌内生菌作为潜在生物防治剂的兴趣日益浓厚，需要进行调查以更好地描述其多样性、分布模式以及在综合虫害管理中的可能应用。我们在美国德克萨斯州对多种棉花品种进行了采样，并测试了真菌内生菌多样性和群落组成的时间和空间变化，以及与有机和常规耕作实践相关的差异。通过形态学和 DNA 鉴定方法对真菌分离物进行了鉴定。我们发现了Alternaria、Colletotrichum 和 Phomopsis 属的成员，这些成员以前是从其他植物物种中分离出来的内生菌。其他回收的物种，如 Drechslerella dactyloides（以前称为 Arthrobotrys dactyloides）和 Exserohilum rostratum，据我们所知，以前没有报道过在棉花中作为内生菌。我们还分离出许多潜伏病原体，但有些物种，如 Alternaria tennuissima、Epicoccum nigrum、Acremonium alternatum、Cladosporium cladosporioides、Chaetomium globosum 和 Paecilomyces sp.，已知是植物病原体、昆虫和线虫害虫的拮抗剂。我们没有发现不同棉花品种之间内生菌物种丰富度或多样性的差异，但确实检测到随时间和不同植物组织的差异。无论使用何种生态群落相似性测量方法，都没有观察到与品种、地区、耕作实践、季节时间或组织类型相关的内生菌群落相似性的一致模式。结果表明，当地的真菌内生菌群落可能受到季节时间和植物组织的影响，但具体的群落组成在不同的地点有所不同。除了提供真菌内生菌群落结构的见解外，我们的调查还为进一步评估作为棉花和其他植物内生菌时潜在的管理工具提供了候选物，以对抗各种病虫害。
