Functional Analysis Of Tomato Cold-regulation Protein SlCOR413IM1

Low temperature is a major environmental factor affecting plant growth,development,productivity,and geographical distribution.To tolerate chilling stress,plants have evolved sophisticated mechanisms to deal with environmental challenge.When plants exposed to chilling stress,the major cold signal transduction pathway,ICE1-CBF-COR,can rapidly response and enhance chilling tolerance of plants.COR proteins are cold regulation protein and can efficiently induce by low temperature.Previous studies have shown that the COR genes were also induced by drought and salt stress.Tomato is a kind of thermophilic vegetable crops originated from tropic,and its growth and development are rather sensitive to environmental stress,especially drought and extreme temperatures.Therefore,it is of great theoretical significance and practical value to explore the physiological function of tomato COR proteins under adversity stresses.In this study,we isolated a cold-regulation gene from tomato,namely SlCOR413IM1.Then we transformed this gene into tomato and tobacco.The roles of Sl COR413IM1 under chilling and drought stress were investigated using sense and antisense transgenic tomatoes and transgenic tobaccos,respectively.The major points are as follows:(1)We isolated the SlCOR413IM1(GenBank number: AK323942.1)gene from tomato leaves.The complete SlCOR413IM1 is 982 bp in length with a 669 bp ORF,a 119 bp 5?-untranslated region(UTR),and a 194 bp 3?-UTR.SlCOR413IM1 encodes a polypeptide of 222 amino acids with a 24.3kDa molecular mass and a pI of 9.75.(2)The vector of SlCOR413IM1-GFP was constructed and transiently expressed in Arabidopsis protoplasts.The confocal microscopy results showed that SlCOR413IM1 is a chloroplast protein.(3)qRT-PCR analysis showed that SlCOR413IM1 expressed in the tomato root,stem,leaf,flower and fruit,and the highest expression in the leaf.The expression of SlCOR413IM1 was induced by cold,heat,drought and ABA.(4)The expression vector of SlCOR413IM1 was constracted.The Agrobacterium tumefaciens-mediated leaf disk method was used to generate sense and antisense transgenic tomato and transgenic tobacco plants.The transgenic plants were detected by PCR and qRT-PCR.The results suggested that sense and antisense transgenic tomato and transgenic tobacco plants were obtained.(5)Under chilling stress,the sense transgenic plants exhibited better growth status of seedling and mature tomato and lower malondialdehyde(MDA)content and relative electrical conductivity(REC)level than WT plants.By comparison,the antisense lines showed obvious growth inhibition and more serious damage of biological membranes.Thus,overexpression of SlCOR413IM1 enhanced the tolerance to chilling stress in tomato,whereas antisense plants with lower SlCOR413IM1 expression had higher chilling sensitivity.(6)Under chilling stress,overexpression of SlCOR413IM1 in tomato reduced the damage of chloroplast membrane and maintained high maximum photochemical efficiency of photosystem II(PSII)(Fv/Fm),net photosynthetic rate(Pn)and actual photochemical effifiency of PSII in the light(?PSII)and the activity of GAPDH and s FBPase.The light inhibition of photosystem II and photosynthetic rate reduced the accumulation of ROS.(7)Under drought stress,overexpression of SlCOR413IM1 in tobacco enhanced drought tolerance by alleviating the accumulation of ROS via antioxidants and antioxidant enzymes and the photoinhibition of photosystem II.However,the high SOD and APX activities in transgenic plants were independent of their transcription levels.