Did you know that soybean (Glycine max) is among the top 5 produced crops in the world? Around 3.3% of the global human calorie intake comes from soybean, which is a rich source of oil and protein. Large-scale production can favor the appearance of diseases, caused by very small plant pathogens such as bacteria, viruses, fungi, and nematodes. These diseases can reduce soybean production and have a negative impact on the entire production chain, influencing the economy and food production. Therefore, understanding the responsible (causal) agents for plant diseases is a key-step in the work of a plant pathologist (a professional who studies plant diseases).
Among the many diseases that affect soybean, anthracnose is caused by species of Colletotrichum. This fungus is classified amongst the top 10 ten genera of most destructive plant pathogenic fungi and is able to infect up to 100% of a soybean field. Colletotrichum species pathogenic to soybean are seed-borne (arrive in new soybean fields mainly through infected seeds), and typical symptoms can appear during all phenological stages of the plants. In the early stages, characteristic symptoms are pre-and post-emergence damping-off. After periods of high relative humidity, the aerial part of the plant becomes symptomatic, and necrosis appears in the petiole and veins, causing leaf rolling which leads to premature defoliation. Lastly, during the early reproductive stages, dark, depressed, and irregular spots can appear in pods, directly affecting seed quality and production.
Currently, the genus Colletotrichum has more than 200 species, most of them classified into 14 species complexes (groups of closely related organisms). Since the first report of soybean anthracnose in 1917, several species of those were reported as pathogenic to soybean, and the identification of the causal agent became a challenge for plant pathologists, as all of them have a similar morphology when observed under a microscope. In our work, we found that around 37% of causal agents of soybean anthracnose are misidentified in public databases. This information is worrying since the correct identification of the causal agent of a disease is essential for effective control strategies to be applied in the field. In the pathogen profile entitled “Soybean anthracnose caused by Colletotrichum species: Current status and future prospects” we provided a platform with current knowledge of this disease, highlighting important knowledge gaps that have not yet been investigated and can be used as a guide for future research of this disease.
Thais R. Boufleur, Maisa Ciampi‐Guillardi, Ísis Tikami, Flávia Rogério, Michael R. Thon, Serenella A. Sukno, Nelson S. Massola Júnior and Riccardo Baroncelli published this study in Molecular Plant Pathology:
TITLE IMAGE: Typical anthracnose symptoms (dark and irregular spots) in all tissues of a soybean seedling (Cotyledons, hypocotyl, petiole and leafs). These symptoms are caused by Colletotrichum truncatum. Credit: Boufleur, T.R. All images used with permission of the author.