Morphological and molecular characterization of Curvularia lunata pathogenic to andropogon grass

ABSTRACT The fungal genus Curvularia is associated with a number of diseases in plants, commonly producing foliar spots in forage grasses. The objective of this study was to characterize the morphological and molecular diversity of the isolates of Curvularia sp. associated with Andropogon seeds, and to assess both their capacity to transmit disease and the pathogenicity of this fungus to crop. Ten isolates of Curvularia sp. were sourced from Andropogon seeds from agricultural producing regions in the Brazilian states Tocantins and Pará. Morphological characterization was achieved by observing fungus colonies and conidia and molecular characterization by DNA extraction and amplification with sequence-specific primers. The disease transmission was evaluated from seed sowing, in which after 40 days typical symptoms of Curvularia sp. were observed. Pathogenicity was evaluated by inoculating conidial suspension into the leaves of healthy plants, and after ten days, inspecting for pathogenic symptoms. Based on morphological and molecular features, the pathogen associated with Andropogon seeds was identified as Curvularia lunata, which, as such, is transmitted through the Andropogon plants via its seeds and is pathogenic to this species of forage grass.

摘要 弯孢霉属（Curvularia）真菌可引发多种植物病害，常在饲用禾草中诱导叶斑症状。本研究旨在明确与须芒草（Andropogon）种子相关的弯孢霉属未定种（Curvularia sp.）分离物的形态与分子多样性，并评估其病害传播能力以及该真菌对作物的致病性。研究从巴西托坎廷斯州与帕拉州的农业产区的须芒草种子中，分离得到10株弯孢霉属未定种菌株。通过观察菌落与分生孢子完成形态学表征，通过DNA提取、序列特异性引物扩增完成分子生物学表征。病害传播能力通过种子播种实验评估：播种40天后，观测到典型的弯孢霉属未定种病害症状。致病性实验则通过将分生孢子悬浮液接种至健康植株叶片，10天后检查致病症状。结合形态学与分子生物学特征，本次研究从须芒草种子中分离得到的病原菌被鉴定为新月弯孢霉（Curvularia lunata），该病原菌可通过须芒草种子实现跨植株传播，并对该饲用禾草具有致病性。