Rust pathogen identification and mechanism of disease-resistance research on Kentucky bluegrass dwarf mutant

Rust is one of the destructive diseases on turfgrass. The species of rust pathogens are multiple and difficult to identify. In order to determine the rust pathogen species on Kentucky bluegrass wild type and dwarf mutant plant, pathogen morphology, along with ITS and β-tubulin gene sequence analysis were carried out. The analysis of ITS by BLAST and phylogenetic analysis of β-tubulin showed that the strains were related to Puccinia graminis of wheat, so we identified it as Puccinia graminis, which is the first report on Kentucky bluegrass in China. Moreover, transcriptional level of PR1L and NPR1L genes in Kentucky bluegrass inoculated with Puccinia graminis, as well as the expression of PRs protein, were investigated. The results presented that the expression of PR1L and NPR1L genes reached peak at 12 hours induced by Puccinia graminis, and the fold changes in dwarf mutant (A16) were 8.8 and 4.5, respectively, greater than in control wild type (WT). Besides, the expression of PRs in P. graminis infected plants 8 days later was higher than in non-infected plants. Defense mechanism of Kentucky bluegrass to rust was preliminary investigated and it presented the related disease-resistant gene and protein induced by rust pathogen. The research provides foundation for rust prevention and disease resistance breeding on Kentucky bluegrass in future.