Pyricularia pennisetigena as leaf blast disease-causing pathogen in king grass (Pennisetum sinese) and its assessment of the pathogenic risk

Abstract

King grass (Pennisetum sinese), also known as sugar cane grass, is being affected by emerging leaf blast pathogen which is responsible for causing foliar disease in Baoshan City, Yunnan Province, China. The pathogen was isolated from the typical infected plants showing symptoms like eye-shaped and whitish color in the center with brown-black necrotic borders surrounded by a yellow halo sample on potato dextrose agar (PDA) media. The leaves of various plants including maize (Zea mays), hybrid rice (Oryza sativa), and wheat (Triticum aestivum), were inoculated with the pathogen in an in vitro assay to evaluate the infection potential of the pathogen and transmission risk. Our study verified that Psp1 is pathogenic to the king grass leaves and it is considered as the main causal agent of leaf blast in the study area. Further, morphological characterization and molecular analysis based on ITS region and LSU gene confirmed the pathogen as Pyricularia pennisetigena. During pathogenicity assay, both Psp1 and LP11 isolates of a rice blast pathogen induced symptoms of varying severity in a total of different nine plants. Among these, the pathogen Psp1 exhibited significant symptoms, including conidial emergence on king grass leaves (Pennisetum alopecuroides and Pe. flaccidum) indicating high pathogenicity to these plants. This suggests that Psp1 pose a considerable a high pathogenic risk to Pennisetum spp. This work lays a groundwork for future implementation of integrated management strategies for leaf blast in local king grass, offering a theoretical basis and research foundation for such endeavor.