Isolation and Identification Rust Pathogens and the Study of Antioxidant Enzyme Activity and Gene Expression under Rust Infection in Zoysia japonica

Abstract

The goal of this study was to identify the zoysiagrass rust pathogens and to analyze the differences in rust-resistant and rust-susceptible Zoysia japonica germplasm upon inoculation. Based on the assessment of spore morphology and 18S ribosomal DNA (rDNA) molecular identification, the zoysiagrass rust pathogen was identified as Puccinia zoysiae Diet. The development of mycelium, the rate of spreading, and the timing of spore production were more delayed in the rust-resistant (RR) genotype than the rust-susceptible (RS) genotype. After inoculation, the activities of superoxide dismutase (SOD), catalase (CAT), and ascorbate peroxidase (APX) initially decreased, then increased in both the RR and RS genotypes, but the increased enzyme activities were faster in the RR than in the RS genotype. Rust resistance was positively correlated with antioxidant enzyme activity. The observed changes in CAT, POD and APX activity corresponded to their gene expression levels. The results of this study may be utilized in accurately evaluating the damage of rust disease and rust-resistance in zoysiagrass germplasm aimed at breeding the rust-resistant zoysiagrass varieties and improving disease management of zoysiagrass turf.

Physiological and Molecular Responses of Zoysia japonica to Rust Infection

“…The RR and RS materials were originally obtained from the propagation of a single seed and were grown in greenhouse for 3~4 years, with stable phenotypes for rust response. The rust fungi strain used for inoculation was determined as P. zoysiae, based on morphological and molecular identifications by Zhang [25]. The strains were cultured in a climate chamber with temperatures of 15 • C to 25 • C, 90% humidity, and an 8 h photoperiod of 600 µmol•m −2 s −1 .…”

“…To date, the studies on rust disease in zoysiagrass are limited. Our previous works on Z. japonica identified the rust-resistant and susceptible materials [23,24], studied leaf tissue structures after infection [6], and investigated the relationship between antioxidant enzyme activity and gene expression and disease resistance [25]. However, the physiological and molecular mechanisms of rust resistance remain largely unclear in zoysiagrass.…”