Effects of enhanced UV-B radiation on the interaction between rice and Magnaporthe oryzae in Yuanyang terrace
Enhanced ultraviolet–B (UV-B) radiation affected the growth of rice and Magnaporthe oryzae, and changed the interaction between them.Enhanced UV-B radiation (5.0 kJ·m-2) of rice leaves in Yuanyang terrace was conducted before, during, and after infection of the leaves with M. oryzae. The relationship between rice blast and UV-B radiation on the disease resistance of rice and the pathogenicity of M. oryzae was studied, and the effects of enhanced UV-B radiation on the interaction between rice and M. oryzae were analysed. The results showed that (1) enhanced UV-B radiation significantly reduced the rice blast disease index, but as infection progressed, the inhibitory effect of UV-B radiation on the disease was weakened; (2) UV-B radiation treatment before infection with M. oryzae (UV-B+M.) significantly increased the activity of enzymes related to disease resistance (phenylalanine ammonia lyase, lipoxygenase, chitinase, β-1,3-glucanase), and the plants exhibited light-induced resistance; (3) exposure to UV-B radiation after M. oryzae infection (M.+UV-B) did not induce disease course-related protein (PR) activity, but the content of soluble sugar increased, but the content of soluble sugar increased. Alleviating osmotic stress caused by pathogenic fungi infection by active accumulation of soluble sugar; due to this lack of nutrients, it was difficult for the rice blast fungus to grow; and (4) enhanced UV-B radiation significantly inhibited the production of conidia by M. oryzae, and the expression of the pathogenic genes Chitinase, MGP1, MAGB and CPKA was significantly downregulated. The pathogenicity of M. oryzae was reduced by UV-B radiation. The resistance of rice leaves was weakened by simultaneous exposure to UV-B radiation and M. oryzae (UV-B/M.). The resistance of rice leaves was weakened by simultaneous exposure to UV-B radiation and M. oryzae (UV-B/M.). Hence, UV-B radiation can weaken the infectivity of M. oryzae, improve the resistance of traditional rice and contain the disease.