Characterization and Genetic Analysis of Rice Mutant Exhibiting Compromised Non-host Resistance to f. sp. ().

Wheat stripe rust, caused by f. sp. (), is one of the most devastating diseases of wheat in China. Rapid change to virulence following release of resistant cultivars necessitates ongoing discovery and exploitation of new resistance resources. Considerable effort has been directed at non-host resistance (NHR) which is believed to be durable. In the present study we identified rice mutant (compromised resistance to rust 1) that exhibited compromised NHR to . Compared with wild type rice variety Nipponbare, mutant displayed a threefold increase in penetration rate by , and enhanced hyphal growth. The pathogen also developed haustoria in mesophyll cells, but failed to sporulate. The response to the adapted rice pathogen was unchanged in relative to the wild type. Several defense-related genes involved in the SA- and JA-mediated defense pathways response and in phytoalexin synthesis (such as , , and ) were more rapidly and strongly induced in infected leaves than in the wild type, suggesting that other layers of defense are still in effect. Genetic analysis and mapping located the mutant loci at a region between markers ID14 and RM25792, which cover about 290 kb genome sequence on chromosome 10. Further fine mapping and cloning of the locus should provide further insights into NHR to rust fungi in rice, and may reveal new strategies for improving rust resistance in wheat.