Fusarium proliferatum associado ao feijão caupi: caracterização, diversidade genética, distribuição biogeográfica e biocontrole

Abstract

The occurrence of fungi in cowpea seeds results in significant production losses. Although chemical control is widely used to manage pathogens in seeds, it can cause environmental contamination and harm to human and animal health. In this context, seed microbiolization has been gaining prominence as a sustainable alternative to synthetic fungicides. Additionally, understanding the population dynamics of a pathogen is crucial to prevent its spread and enable effective control. Thus, the objective of this study was to evaluate the geographical distribution of Fusarium proliferatum in Brazil, its host range, and different sources of isolation. It also assessed the potential of products based on Trichoderma harzianum, Trichoderma asperellum, and Bacillus amyloliquefaciens on the sanitary and physiological quality of cowpea seeds, as well as the biological control of F. proliferatum associated with this crop. To evaluate the population dynamics of the pathogen in Brazil, a phylogeographic approach using the Translation Elongation Factor 1-alpha (TEF1-α) gene was employed. For the evaluation of the effect of biological products, cowpea seeds, cv. Marataoã, were immersed in suspensions of EcoTrich® (T. harzianum), Quality® (T. asperellum), Pardella® (T. harzianum, T. asperellum, and B. amyloliquefaciens), and Shocker® (T. harzianum and B. amyloliquefaciens). Seed treatment with the fungicide Captan (240g / 100 kg of seeds) and immersion in sterilized distilled water (control) were performed. The health of the treated seeds was evaluated by the Blotter test. Germination and emergence were also assessed. The transmission rate of F. proliferatum was determined through direct contact between cowpea seeds, cv. Marataoã, and the pathogen colony. An in vitro test of direct confrontation and antibiosis with F. proliferatum was conducted. In the greenhouse, the incidence and severity of the disease in treated plants were determined. The fungi associated with cowpea seeds were: Cladosporium sp. (22.5%), Fusarium spp. (7.0%), Aspergillus sp. (7.0%), Alternaria sp. (2.0%), Macrophomina sp. (1.0%), and Penicillium sp. (1.0%). A reduction in the incidence of fungi and an increase in the physiological quality of seeds treated with biological products were observed. F. proliferatum is pathogenic and transmitted via cowpea seeds, cv. Marataoã. Microbiolization reduces the incidence and severity of the disease and promotes the growth of cowpea seedlings.