Molecular Mechanism Of Interaction Between Plant Rhizosphere Bacteria And Plant Root Exudates

Rhizosphericmicroorganism is important components of host plants to adapt to the environment and achieve self-defense.Plants participate in the colonization and interaction of RM in the rhizosphere of plants through various nutrients and signaling molecules in root exudates.Therefore,the relationship between plant root exudates and RM arouse enough attention in the field of rhizosphere microecology in recent years,they play an important role in the growth and disease resistance of plants through coupling interaction.At present,there are some researches on plant disease control and root exudates,but studies on the relationship between microbial control of Botrytis cinerea and root exudates are still rare.In this study,the plants were treated by biological induction or non-biological induction,and the results were analyzed from two aspects:1.Tomatoes were treated with biological induction(Pseudomonas choloeaphtis,Bacillus pumilus)and abioticinduction(methyl jasmonate and β-aminobutyricacid),the root exudates of the plants in each experimental group were extracted and used to perform the in vitro plate resistance test on Botrytis cinerea.It was found that bioinduction can inhibit the growth of Botrytis cinerea,while non-biological induction does not show resistance to gray mold.The root exudates of both bioticand abiotic-induced tomatoes had different degrees of resistance on Botrytis cinerea;the disease index of the plants was significantly lower after induction.2.The species and content of bioticand abiotic-induced plant root exudates was analyzed by GC-MS.The results showed that low molecular weight substances such as malicacid,which are beneficial to plant growth,increased significantly in the root exudates of the plants after induction.3.The total RNA of roots,stems and leaves of tomato plants before and after bioticand abioticinduction were extracted,and the expression levels of target genes NPR-1,PI-1 and PR-1 were detected by fluorescent quantitative PCR.The enzyme activities of superoxide dismutase(SOD),peroxidase(POD)and catalase(CAT)in leaves of plants before and after induction were measured and compared.Results indicate that bioticand abioticinduction protected the activity of leaf antioxidant enzymes to varying degrees.Bacillus pumilus mainly enhances disease resistance through SA metabolicpathway,while Pseudomonas choloeaphtis,methyl jasmonate and β-aminobutyricacid can simultaneously increase the disease resistance of plants by participating in SA and JA metabolicpathways.In summary,rhizosphere microbes(biological induction)and abioticinduction can effectively protect plant antioxidant enzymes,and increase the expression of key enzyme genes in the disease resistance metabolicpathway,and use root exudates as an important medium to make tomatoes have a characteristicof disease resistance.Further concluded that rhizosphere microorganisms and root exudates interact with each other to produce and enhance their disease resistance.This research provides an effective solution to the biological control of soil-borne disease gray mold,provides new insights for the green development of agricultural products,and has certain application significance for the research progress in the field of micro-ecology.