Recently, the team of Professor zhangzhengguang of Nanjing Agricultural University published a research paper entitled”co evolved ascorbate oxides of plant and the blast fengus orchestrate host apoplast redox state to modular rice immunity” on the top journal”molecular plant” in the field of Botany.
Rice blast caused by Magnaporthe oryzae is a devastating disease of rice, known as”rice cancer”. In the face of the”attack” of Magnaporthe grisea, rice cells build their own defense fortress by accumulating a large amount of reactive oxygen species to resist the infection of the pathogen. As the first battlefield of the interaction between host plants and pathogens, the level of reactive oxygen species in apoplast space is strictly controlled by the plant redox system. As an important component of the extracellular redox system, the dynamic balance of extracellular ascorbic acid is precisely regulated by ascorbic acid oxidase, thereby maintaining the level of extracellular reactive oxygen species. It can be seen that the apoplast redox system plays an important role in controlling plant immunity, so as a”battlefield”, how do pathogens hijack the apoplast redox system to achieve infection?
This study found that Magnaporthe grisea entered the rice apoplast space through the secretion of monomer ascorbic acid oxidase moao1, manipulated the redox balance of rice apoplast, and then inhibited the burst of reactive oxygen species. Researchers also found that moao1 competitively combines ascorbic acid oxidase osao3 and osao4 in rice exosomes to form heterodimers, hindering the formation of their own homodimers of osao3 and osao4, thus inhibiting the oxidation ability of osao3 and osao4 against ascorbic acid, resulting in a highly reduced state in the apoplast space, inhibiting the accumulation of reactive oxygen species, and promoting bacterial infection.
In order to cope with the”attack” of moao1 secreted by Magnaporthe grisea, rice osao3 and osao4 showed rich sequence polymorphisms in the coevolution process. Without affecting their own enzyme activities, they avoided the recognition of moao1, resulting in the inability of moao1 of the pathogen to form heterodimers with it, thus re establishing the apoplast redox homeostasis and maintaining the resistance of rice to Magnaporthe grisea. The research system revealed the specific mechanism of the coevolution and mutual adaptation of extracellular oxidoreductase in the interaction between Magnaporthe grisea and rice, and took the lead in analyzing the molecular mechanism of plant pathogens manipulating the host exosome redox balance system to monitor host immunity. The research results can be expected to provide genetic resources for disease resistance breeding and provide reference for the design of new fungicide targets based on the pathogenesis.
Hu Jiexiong, a doctoral student from the Plant Protection College of Nanjing Agricultural University, is the first author, and Professor Zhang Zhengguang is the corresponding author. Professor Zhang Haifeng, Associate Professor Liu Juju and associate professor Shen Danyu of Nanjing Agricultural University, Professor Ping Wang of Louisiana State University, Professor Bo Zhou of the International Rice Institute and researcher Zhou huanbin of the Plant Protection Institute of the Chinese Academy of Agricultural Sciences participated in the study. The research was supported by the innovative research group, key projects and general projects of the National Natural Science Foundation of China.
In recent years, with the support of national, provincial and ministerial projects, Professor Zhang Zhengguang’s research group has been committed to the study of the pathogenesis of Magnaporthe grisea, and has made a series of progress in the interaction between Magnaporthe grisea and rice. Relevant research results have been published in PNAS, eLife, autophagy, PLoS pathogens, PLoS Genetics, new Phytologist, mbio and other mainstream journals of pathogenic biology and plant pathology.