Study On The Stress Resistance Of Potato StSUT2-RNAi Transgenic Strain

Potato(Solanum tuberosum L.)is a genus of Solanaceae.It is a high-yield combination of grains,vegetables and feed,and is one of the four main crops in the world.Plant sucrose transporter(SUT)is mainly responsible for the long-distance transportation of sucrose from the "source" organ to the "sink" organ.It also controls the distribution of sucrose in the plant body,affects the growth and development of the plant,and determines the yield and quality of the crop.Potato SUT families are StSUT1,StSUT2,and StSUT4.Recent studies have shown that StSUT1 and StSUT4 affect potato plant growth,tuber yield and photoperiod-regulating gene expression,while the physiological functions of StSUT2 are still unclear.In this study,the potato cultivar "Sharpotie" and its transgenic lines RNAi-1 and RNAi-2 with down-regulated expression of StSUT2 were used as materials to analyze its response to abiotic stress conditions such as high salt,drought,low temperature,and high temperature.The tolerance differences shown by non-transgenic plants and transgenic lines were analyzed for the tolerance differences of sugar starvation stress,as well as the effect of Brassinosteroid on sugar starvation stress;the q TR-PCR method was used to analyze The expression levels of brassinolide signaling pathway-related genes and genes related to cell wall formation in non-transgenic plants and wild-type plants before and after stress,so as to explore the regulation mechanism of StSUT2 gene on potato stress tolerance.The experimental results are as follows:There is a certain difference in morphology between the transgenic line StSUT2-RNAi and the non-transgenic plant under abiotic stress.(1)StSUT2-RNAi strain under a certain concentration of 25,50 mmol/L NaCl,the fresh weight,number of new leaves,number of stem nodes,and plant height of the transgenic strain StSUT2-RNAi are higher than those of the wild type.This preliminarily shows that the salt tolerance of StSUT2-RNAi strain is higher than that of wild-type plants.(2)The potted seedlings of the transgenic line StSUT2-RNAi and non-transgenic plants were treated with drought.The non-transgenic plants began to curl and the stems fell after 7 days of treatment,while the transgenic lines RNAi-1and RNAi-2 were treated at 9 days and At 12 days,the leaves began to wilt and the stems fell.This result preliminarily indicates that the drought tolerance of StSUT2-RNAi lines is higher than that of non-transgenic plants.(3)The transgenic line StSUT2-RNAi and the potted seedlings of non-transgenic plants were treated with-2℃ low temperature stress.When the non-transgenic plants were treated for 1 h,the leaves began to wilt,appear water-stained,and the stems fell,while RNAi-1,RNAi The leaves of the-2 line began to wilt and the stems fell when treated for 2.5 h and 4 h,respectively.This result preliminarily indicates that the low temperature tolerance of StSUT2-RNAi strain is higher than that of non-transgenic plants.(4)The transgenic line StSUT2-RNAi and the potted seedlings of non-transgenic plants were treated with 42℃ high temperature stress.The leaves of the non-transgenic plants and RNAi-1 lines began to wilt and the stems fell when the stress was 2.5 h;while the RNAi-2 lines After 5 h,the mature leaves wilted and the stems fell.This preliminarily shows that the high temperature tolerance of StSUT2-RNAi strain is higher than that of non-transgenic plants.(5)The morphological response of transgenic plants StSUT2-RNAi and non-transgenic plants under sugar starvation and BR treatments showed that the tolerance to sugar starvation stress was higher than that of wild type;BR treatment had a stronger inhibitory effect on the roots of wild type plants.(6)Under normal growth conditions and salt stress treatment conditions,the expression of St BRI gene in the two StSUT-RNAi transgenic lines was significantly higher than that of non-transgenic plants.This indicates that StSUT2 may increase the tolerance to salt stress by affecting the expression of St BRI gene.Under normal growth conditions and sucrose starvation stress,the expression of St DHE gene in the two StSUT-RNAi transgenic lines was significantly higher than that of non-transgenic plants.This indicates that StSUT2 may regulate the formation of potato cell wall by affecting the expression of St DHE gene,which may be the main reason why the stems of transgenic lines are prone to lodging under sugar starvation stress.