Pathogenicity of fungi associated with Andropogon grass seeds

Abstract

Andropogon L. is a perennial forage grass propagated by seeds, which is widely distributed in areas of Tropical Cerrado, Brazil. It is a robust plant commonly used in the formation and recovery of pastures, as it is low demanding in terms of soil fertility and management. However, little is known about the fungi associated with this forage grass, especially in its seeds, which are propagation structures capable of transporting fungi to new cultivation areas. The aim of this study was to evaluate the health of Andropogon seeds and the pathogenicity of these fungi associated with seeds to the plant itself and to other crops. Trials were carried out with ten seed samples collected in regions of agricultural importance in Brazil. Phytopathogens such as Alternaria alternata, Curvularia lunata, Bipolaris oryzae and Phoma sorghina isolated from Andropogon seeds were identified, which, after inoculation, caused disease symptoms in rice, cowpea, watermelon, melon, maize and other forage grasses. In the Cerrado area, the seeds of this forage are often found in degraded fields, on the roadsides and around annual crops, thus serving as vehicles of dissemination and alternative hosts of pathogenic fungi for crops of agricultural importance. In addition to crops of economic interest, the pathogens B. oryzae and C. lunata were pathogenic to Andropogon grass, which could affect the development and establishment of this forage crop in the field. The fungal genera Cladosporium, Fusarium, Penicillium and Rhizopus associated with Andropogon grass seeds reduced the sanitary quality of the lots and can interfere with germination and emergence, as they are responsible for the seed and plant tissue deterioration. The results of this study provide important and unprecedented information on the health of Andropogon grass seeds, a very common genus in Brazilian Cerrado pastures.