Population diversity and variation of the rice blast fungus under different climate conditions

Abstract

The natural environment is a critical factor for the epidemiology of rice blast. To demonstrate the population variation of rice blast field isolates in distinct climates of different years, 57 isolates from rice panicle blast samples in Dawei Mountian district of Hunan province were surveyed from 2013 to 2015. In July and August, the key period for the occurrence of rice panicle blast, there was obvious discrepancy among weather conditions over 3 years. The climate in 2013 was the most arid, better in 2014, and the most suitable was in 2015. For isolates purified in different climates, the pathogenicity assay on twenty-four rice monogenic lines (MLs) showed that the effective resistance (R) genes were Pi5 and Pi1 in 2013; Pi1 in 2014; Pita2, Piz5 and Pi9 in 2015. The genomic analysis based on repetitive element-based polymerase chain reaction (Rep-PCR) also confirmed that there was critical discrepancy among isolates in 3 years. The colony morphology performance at 32 °C high temperature showed that isolates in 2013 were smaller, and with more dense and compact mycelium than isolates in 2014 and 2015. These findings revealed the variation and rich population diversity of the rice blast field fungus under different environments, even in a limited location.