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Effects Of Drought Stress At Tillering Stage On Rhizosphere Microbial Community Of Rice With Different Drought Resistance And Its Mechanism

Posted on:2022-10-27Degree:MasterType:Thesis
Country:ChinaCandidate:G G LiFull Text:PDF
GTID:2480306512999579Subject:Crop Science
Abstract/Summary:PDF Full Text Request
At present,as the demand for rice increases and the sown area decreases,ensuring the normal growth of rice at the tillering stage has an important impact on stabilizing and increasing the total output of rice in my country.The rainfall is low in this period,so the rice is susceptible to drought stress.In severe cases,it will cause a large number of tillers to die,and ultimately cause a significant decline in yield.Rhizosphere soil microorganisms and root exudates both play a key role in plant resistance to drought stress,but whether there are differences in the changes of rhizosphere soil microorganisms of different drought-resistant rice varieties under drought stress at the tillering stage,and whether the changes of rhizosphere soil microorganisms under drought stress are regulated by root exudates,there are lack of relevant research.Based on this,this study selected two rice varieties with different drought resistance,Nipponbare(weak drought resistance)and Luodao 998(strong drought resistance),and conducted drought stress at the tillering stage to compare the growth,rhizosphere microbial community and root exudates of the two rice varieties.The effect of drought stress at tillering stage on rhizosphere microbial community of rice with different drought resistance and its mechanism were studied from plant-microorganism perspective.The specific results are as follows:1.Drought stress at the tillering stage inhibited the tillering of Nipponbare,but had no significant effect on the tillering of Luodao 998.At the same time,the total root length per plant,root surface area,whole plant dry matter weight,aboveground dry matter weight and root dry matter weight of the two rice varieties were significantly reduced,and the decline of Luodao 998 was less than that of Nipponbare.In addition,the root system of Luodao 998 can accumulate more total soluble sugar and maintain a certain proportion of soluble sugar distribution,which may be an important physiological reason for its strong drought resistance.2.After the drought stress at the tillering stage,the Alpha diversity of the rhizosphere soil bacterial communities of the two rice varieties did not change significantly.However,the composition of the rhizosphere soil bacterial community was significantly affected by drought stress.At the phylum level,Nipponbare enriched Actinobacteria and Gemmatimonadetes,reduced Firmicutes and Bacteroidetes,while Luodao 998 enriched Patescibacteria.In addition,there were also certain differences in the function of the rhizosphere soil bacterial flora of the two rice varieties in response to drought stress.The carbohydrate metabolism,amino acid metabolism,energy metabolism,nucleotide metabolism,lipid metabolism,the metabolism of terpenoids and polyketones of the Nipponbare rhizosphere soil bacterial community were significantly enhanced,and the biosynthesis and metabolism of polysaccharides and the immune system of the Luodao 998 rhizosphere soil bacterial community were significantly enhanced.3.After the drought stress at the tillering stage,Luodao 998's root metabolism activity was more vigorous,but the expression of sugars,alcohols,and sphingolipids in its root exudates were significantly reduced.Nipponbare's root exudates accumulated a large amount of amino acids and its derivatives and other substances.In the metabolic pathway,the differential metabolites of Nipponbare normal control and drought stress treatment were mainly in glycine,serine and threonine metabolism,monocyclic lactam biosynthesis,purine metabolism,plant hormone signal transduction,indole alkaloid synthesis and the pentose phosphate pathway were significantly enriched,among which the glycine,serine and threonine metabolic pathways were more enriched.The different metabolites of Luodao 998 normal group and drought stress group were mainly significantly enriched in amino acid biosynthesis,glucosinolate biosynthesis,2-oxycarbonyl salicylic acid metabolism,aminoacylt RNA biosynthesis,valine,leucine and isoleucine biosynthesis pathways,among which the amino acid biosynthesis pathway had the most significant enrichment degree,and the enrichment degree was greater.And under drought stress at the tillering stage,there was a significant correlation between root exudates and rhizosphere soil bacterial communities,which indicates that root exudates may have a significant impact on the rhizosphere soil bacterial community composition,which may affect the drought resistance of rice.
Keywords/Search Tags:Rice, Tillering stage, Drought stress, Rhizosphere microorganisms, Root exudates
PDF Full Text Request
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