Preliminary Application Of Methane Regulating Plant Growth,development,and Salt Tolerance

In recent years,the increasingly serious salinization of land has become an important reason for reducing world crop production.Therefore,the theory and practice of plant salt tolerance is one of the hot research topics.Previous studies had shown that methane(CH4),as a signaling molecule,could participate in the regulation of plant growth and development,and improve plant salt tolerance,but lack of practical application.In view of the above problems,this paper firstly clarified that CH4 had a certain regulatory effect on plant growth and development through biochemical and pharmacological experiments,and then explored the regulation of CH4 on the growth and physiological characteristics of rape seedlings under salt stress.Based on the above results,this paper designed a methane-rich water irrigation device which could be applied in the field of agricultural technology,and could be applied in farmland.In addition,in practice,it was also found that CH4 could induce lateral root(LR)formation in tomato.Therefore,the regulation mechanism of NO in CH4-induced LR formation was further explored from the perspective of nitric oxide(NO)signaling molecules.The main results are as follows:(1)Exogenous CH4(methane-rich water)could regulate the growth and development of plant seedlings extensively.Because the above effects were species-specific,the optimum concentration of CH4 for various plants(tomato,cucumber,chicken cabbage,maize,rape)was different,and the main optimum concentration range was 0.65～1.04 mM.The growth status of plant seedlings treated with CH4 was significantly better than that of control group without CH4 treatment,including increasing biomass accumulation,root vigor,soluble protein and soluble sugar content,and chlorophyll content.(2)CH4 pretreatment could promote the biomass accumulation of rape seedlings under salt stress,enhance root activity,maintain intracellular ionic homeostasis and alleviate the ionic toxicity caused by salt stress;at the same time,CH4 pretreatment could also help improve the ability of crops to synthesize osmotic regulators(soluble sugar and proline),increase chlorophyll content,accelerate photosynthesis efficiency and help accumulate organic matter.In addition,CH4 pretreatment also activated the activities of antioxidant enzymes(SOD,POD,and CAT)in vivo,and improved their antioxidant capacity,thereby alleviating oxidative damage.In conclusion,exogenous CH4 pretreatment could effectively alleviate the inhibition of rape seedling growth under salt stress,improve the antioxidant capacity,and thus improve its salt tolerance.(3)This paper designed a methane-rich water irrigation device which could be applied in the field of agricultural technology.The main body of the irrigation device included a cylindrical methane-rich water storage tank,a cylindrical water tank,a control center,a mixed water storage tank,a labyrinth drip irrigation belt and a control center.The device mainly adopted automatic control mode,which could make good use of methane-rich water to irrigate crops and horticultural flowers.The methane-rich water irrigation device has applied for a patent for utility model,and application number is 201821801899.7.(4)In practice,we also found that CH4 can induce lateral root(LR)which belongs to plant development,but its downstream signaling molecules are not yet clear.Further studies showed that exogenous CH4 promoted the rapid production of NO in tomato seedling roots,while NO scavengers(cPTIO and PTIO)inhibited the formation of lateral root primordia,thereby blocking the formation of lateral roots induced by CH4.Molecular evidence suggested that both exogenous CH4 and SNP could regulate the transcriptional levels of cell cycle regulatory genes(SlCYCA2;1,SICYCA3;1,SICDKA1 and SIKRP2)and related genes(miR160 and miR390)and their target genes(SlARF4 and SIARF16)related to lateral root formation,but the above regulatory effects were reversed by cPTIO and PTIO.Genetic evidence showed that a nitrate reductase mutant(Atnia2)in Arabidopsis exhibited a decrease in NO content in lateral roots and a defect in lateral roots formation.Further treatment with CH4 or SNP(better effect)could alleviate the above phenomena.The above changes were also consistent with the changes in LR-related gene transcripts.In conclusion,these results provided direct molecular and genetic evidence that NR-dependent NO was at least partially a downstream signaling molecule for CH4-induced lateral root formation in tomato.In conclusion,exogenous CH4 could promote plant growth and development,including inducing lateral root formation,and effectively alleviate the inhibition of rape seedling growth under salt stress,thereby enhancing its salt tolerance.Finally,a methane-rich water irrigation device was applicated for patent for utility model,so as to apply in field practice.