Effect Of Exogenous Trehalose On Sugar Metabolism Response To Salt Stress In Tomato Seedlings

Plants accumulate more soluble sugars under salt stress,maintain cell osmotic potential,and redox levels.At the same time,sugar as a signaling molecule used to regulate the expression of stress-related genes,and improving the salt tolerance of plants.Based on the preliminary results of RNA sequencing(RNA-Seq),the paper focused on the effects of exogenous trehalose on the accumulation of sugar,the expression of key genes involved in sugar metabolism and the metabolism of ABA in tomato seedlings using the Ailsa Craig wild type tomato cultivar.This study provide theoretical basis for obtaining high resistance of tomato varieties.The results are as follows:The research results showed that the plant height,fresh weight and relative water content of the leaves were reduced in salt stress and the leaves withered.Meanwhile,the activity of antioxidant enzymes and proline content were decreased.Low concentration of trehalose treatment increased the plant height,fresh weight,leaf water content,chlorophyll content and proline content of tomato seedlings in salt stress,enhanced activity of antioxidant enzymes,while reduced the MDA content.The high concentration of trehalose inhibited the growth of tomato and showed the opposite trend with low concentration trehalose.Finally,the optimal concentration of trehalose was 2m M by TOPSIS method.Analysis of tomato sugar accumulation showed that exogenous trehalose reduced the accumulation of starch in tomato leaves and roots under salt stress,and alleviated the negative feedback mechanism of photosynthesis.However,the accumulation of soluble sugar content in tomato leaves and roots under salt stress,especially sucrose content,increased plant ionic stress,maintained plant cell stability,and enhanced plant salt tolerance.Studies on key genes in glucose metabolism indicated that exogenous trehalose inhibited the expression of key genes for starch synthesis(SS/AGPase)and trehalose phosphatase(TPP)in tomato under salt stress;up-regulated key genes of starch metabolism(BAM1/AMY)and sucrose phosphate synthase gene(SPS),acid invertase gene(Wiv1),trehalase gene(Tre)and trehalose phosphate synthase gene(TPS).Studies on sugar transporter indicated that exogenous trehalose up-regulated the fructose phosphokinase gene(FRK2),fructokinase gene(PFK),hexokinase gene(HXK2/HXK3),and and sugar transporter gene(MST3/SUT1/SUT4)in tomato under salt stress.This suggests that trehalose may alter the source-storage pathway of sugar to alter the accumulation and distribution of sugars in response to salt stress in plants.The results of ABA anabolism showed that exogenous trehalose induced the expression of ABA synthesis genes(NCED1 and NCED2)in tomato seedlings under salt stress,and inhibited the key genes of ABA metabolism(CYP707A1 and CYP707A2)to further increase endogenous ABA content.