Preliminary Study On The Mechanism Of Hydrogen Gas Enhancing Plant Resistance To Rice Stripe Virus

Rice stripe disease is one of the most important diseases that crop production regions in China and even the world today are faced.It seriously affects the yield of crops.To explore the resistance mechanism that host plants defencing rice stripe virus（RSV）is of great significance.In recent years,most studies have found that hydrogen gas（H₂）plays an important role in improving host resistance to pathogens.However,most research about H₂ participating in improving the resistance of pathogens has focused on animals and fungi.There are relatively few studies on anti-viral,and it is still unclear whether H₂ is involved in the defense response of plants to RSV.In view of the above problems,this article have found that:1)H₂ can increase the resistance of host plants to RSV;2)H₂ can promote the accumulation of free SA under RSV stress,and induce the up-regulation of disease-related genes such as SA synthesis pathway genes（ICS1,PAD4,NPR1,and PRs）to improve plant resistance.The specific research results are as follows:1.RSV can induce endogenous H₂ production in rice.H₂ can increase the resistance of host plants to RSV.Gas chromatography（GC）results showed that the H₂ content in resistant/susceptible rice varieties under RSV infection was significantly different,and the resistant varieties were significantly higher than the susceptible varieties.Exogenous application of H₂（in the form of Hydrogen-rich water）can reduce the incidence of RSV in a concentration-dependent manner.At the same time,the decrease expression of viral CP（Coat protein）gene and protein levels after exogenous application of H₂ also indicated the resistance results.DCPIP（inhibitor of photosynthetic electron transport chain,which can suppress the production of H₂）can exacerbate RSV expression,and applying H₂ externally can reverse the process.Previous experiment results have found that rice stripe virus can successfully infect Arabidopsis thaliana,and there no report that hydrogenase can synthesize H₂ in higher plants.Thus the CrHYD1 transgenic Arabidopsis material（overexpressing the Chlamydomonas reinhardtii hydrogenase gene CrHYD1）previously constructed was used to explore the function of H₂ in plant response to RSV.Genetic experiments have found that H₂ can inhibit the expression of RSV and improve plant resistance.In conclusion,genetics,pharmacology,and biochemistry experiments have confirmed that H₂ can increase the plants RSV resistance.2.H₂ promoted the accumulation of SA under RSV stress,and induced the upregulation of SA-related genes ICS1,PAD4,NPR1,PRs and other disease-resistant genes.qRT-PCR showed that exogenous application of H₂ could induce disease-related hormones such as salicylic acid（SA）,jasmonic acid（JA）,brassinolide（BR）changes in the level of gene transcription under RSV stress in susceptible varieties.Among them,NPR1 and other SA pathway related genes were significantly up-regulated.UPLC results also indicate that exogenous application of H₂ significantly increases the free SA content in resistant/susceptible rice varieties under RSV stress.Similarly,CrHYD1 transgenic Arabidopsis can promote free salicylic acid accumulation under RSV stress.DCPIP treatment could induce the upregulation of SA glucosyltransferases（SAGT）gene,promote the conversion of free SA to SAG（SA-2-O-β-D-glucoside）,reduce the content of free SA,and induce the downregulation of SA pathway genes.The qRT-PCR results further confirmed that SA synthesis-related genes ICS1,PAD4 and SA downstream PRs genes were up-regulated after exogenous application of H₂ under RSV stress.In summary,this article reveals that H₂ can induce the upregulation of SA synthesis pathway genes ICS1,PAD4,promote the accumulation of free SA and induce upregulation of NPR1,PRs genes under RSV stress which participated in the basic resistance of plants against rice stripe virus.It provides a basis for understanding the mechanism of H₂ participated in plant defense against viruses.