Pathogenicity and Genetic Variations in Magnaporthe oryzae Isolates from One Rice Variety Planting in Paddy and Upland Fields

Abstract

Rice is the most important crop for worldwide consumers. The water utilization of rice planting is more than 50% of agricultural water in China, and it is necessary to breed water-saving and drought-resistant rice. The rice variety Dianheyou 615 can be planted in the paddy and upland fields, which satisfies rice production farmers in mountainous regions of Yunnan. We aimed to explore the variations in Magnaporthe oryzae isolates collected from Dianheyou 615 planted in paddy or upland fields. Through pathogenicity tests, we found that most isolates had the highest pathogenicities, but there were no significant differences between the paddy and upland isolates. By a combination of monogenetic and elite rice lines, with a further resistance assessment, the monogenetic lines with Pi9, Diantun 506, and Lvhan 1 displayed better resistances. Moreover, we re-sequenced 15 isolates to explore their genetic variations. Our results showed that the source of the upland isolates may have been the offspring of the paddy isolates, but there were many genes with specifically found SNPs in two populations that would develop subdivisions after long-time planting. Overall, we compared the pathogenicities and genetic variations in blast isolates from the planting of Dianheyou 615 in paddy and upland fields, which provided references for the influence of the planting environment on population subdivisions.