Effects Of Silicon On Growth And Physiological Characteristics Of Oat Under PEG Stress And Transcriptome Analysis

Oats are annual forage crops of gramineous family.They have excellent traits such as cold resistance,high grass yield and high nutritional value,and they play an important role in the forage industry.In China,arid and semi-arid areas reach half of the country's land area,and even in non-arid areas,they are often subject to periodic or unpredictable drought stress.In recent years,there have been many reports on the beneficial effects of silicon on plant growth and development under abiotic stress,but the mechanism by which silicon affects oats under drought stress is unclear.Therefore,the study of the mechanism of silicon to alleviate drought stress provides a theoretical basis for oat breeding and cultivation in arid areas.This test variety is the Canadian introduced variety Tianyan No.1,using Na2SiO3·9H2O as the silicon source,using PEG-6000 to simulate the drought stress environment,and studied normal growth,drought stress(25%polyethylene glycol,PEG-6000)and silicon+ The effect of drought stress(10 mmol/LNa2SiO3·9H2O+25%PEG-6000)on oat seedlings,the results are as follows:(1)Si treatment significantly increased(P<0.05)net photosynthetic rate(Pn),transpiration rate(Tr),stomatal conductance(Gs),intercellularCO2 concentration(Ci),chlorophyll a,chlorophyll b,chlorophyll a+b,the basis fluorescence(Fo),the max fluorescence(Fm),the maximum quantum efficiency photochemistry(Fv/Fm)and performance index PIABS,and decreased(P<0.05)Malondialdehyde,proline and the activities of peroxidase in shoots and roots,decreased(P<0.05)soluble protein contents and the activities of superoxide dismutase in shoots,increased(P<0.05)soluble protein contents and the activities of Superoxide dismutase in roots,and decreased nitrogen and calcium content in leaves,increased the phosphorus,potassium and silicon content in leaves.Application of exogenous silicon could improve the photosynthesis,activities of antioxidant enzymes,activate the osmotic adjustment of oat seedlings under drought stress.In the drought stress,root coud play important roles in maintaining leaf physiological indexes at a certain level,relieve adverse effects of drought stress on oat seedlings,and then promote oat growth.(2)Conditions by conducting a large transcriptomic analysis(116,843 unigenes)aimed at comparing the differential response of plants under the three treatments.The comparative transcriptomic analysis revealed that Si played an important role in shaping the transcriptome of oat:Under drought stress,silicon played an important role in changing the expression levels of 756 genes.KEGG enrichment analysis showed that enzymes related to soluble sugars were significantly enriched.(3)Oats were analyzed by transcriptome analysis(176,555 single genes)in order to compare the differential genes of plants under the three treatments.Comparative transcriptomics analysis showed that silicon plays an important role in changing the expression levels of 234 genes under drought stress.GO enrichment analysis showed that the enrichment of related genes such as oxidoreductase activity,cellular nitrogen compound metabolism,and cellular macromolecular metabolism significantly increased,and these genes are inextricably linked to abiotic resistance,indicating that silicon May induce drought tolerance in oat seedlings.By studying the mechanism of silicon-mediated drought resistance,it provides a theoretical basis for the application of silicon in crop production in arid regions.