Preliminary Study On The Effect And Mechanism Of Exogenous Silicon On Alleviating Salt Stress In Rice

Soil salinity is one of the main environmental constraints of crop production.In recent years,with the rapid development of China’s social economy and the continuous advancement of industrialization,the degree of soil salinization is increasing.Rice is a moderately salt sensitive crop,especially in the seedling stage.In this study,the effects of Exogenous Silicon on the growth indexes,antioxidant enzyme activities,potassium and sodium ion content of rice seedlings under salt stress were analyzed by water culture and soil culture,and the differentially expressed proteins in rice roots were analyzed,so as to preliminarily explore the effect and mechanism of silicon on alleviating salt stress in rice.By means of hydroponic experiments,two treatments of salt stress（0.5%Na Cl）and exogenous silicon（3 m M Na₂Si O₃）+0.5%Na Cl were set to determine the leaf and root morphology,growth indexes,antioxidant enzyme activity and malondialdehyde（MDA）content of P.nipponica seedlings under salt stress.The results showed that exogenous silicon alleviated salt damage of rice seedlings under salt stress,the salt injury index decreased from 63.0%to 41.2%,which increased leaf and root activity,increased biomass accumulation,promoted root biomass accumulation and seedling length and leaf length significantly,and increased antioxidant enzyme activities.The activities of CAT and APX activities were improved,and also significantly reduced MDA accumulation in plants.Pot experiments were conducted to determine the effects of Exogenous Silicon on potassium and sodium contents in the aboveground and underground parts of L7 and L15seedlings under salt stress.After treatment with 0.5%Na Cl for 7 days,the symptoms of salt damage of the two varieties changed from light to heavy,which were Na Cl+sodium silicate,Na Cl+1/4 diatomite,Na Cl+1/2 diatomite and Na Cl.Under salt stress,Na⁺content in roots of L7 and L15 decreased by 76.0%-84.9%and 44.4%-75.3%,respectively.The results showed that sodium silicate was better than diatomite in alleviating salt stress.The addition of exogenous silicon could significantly reduce the accumulation of Na⁺in the roots of rice seedlings,regulate the ion balance in cells,and improve the salt tolerance of rice seedlings.The results showed that the expression of Os DRP2B and benzoyl transferase were inhibited under salt stress,while the expression of Os DRP2B was slightly up-regulated under salt stress.However,the expression of heat shock protein Os HSP71.1 was up-regulated under salt treatment alone,and decreased after exogenous silicon treatment.The xylanase inhibitor Os HI-XIP and chitinase CHIT14 were down regulated under salt treatment,but the expression level did not increase after exogenous silicon treatment.In conclusion,silicon can alleviate salt stress in rice seedlings by regulating antioxidant enzyme activities,reducing MDA content in plants and Na⁺content in roots,and regulating the expressions of Os DRP2B,OSHSP71.1 and benzoyl transferase in roots.