Cloning And Preliminarily Functional Analysis Of SlMYB102 On Salt Stress In Tomato

Tomato(Solarium lycopersiczum L.)is one of the universal vegetables with high economic and nutrition value which is widely loved by people.China is the largest country in tomato production all over the world.Therefore,it's important to improve the yield and quality of tomato.However,in actual production,the yield and quality of tomato was always influenced by various abiotic stresses,especially salt stress.The MYB transcription factor is one of the most important transcription factors in plant.Researches had shown that the spatio-temporal expression of MYB transcription factors are specific and they are widely involved in plant growth and stress resistance.In our study,we cloned a tomato stress response R2R3MYB gene,SIMYB102,and further studied the gene function.The main results are as follows:Bioinformatics analysis showed that SIMYB102 encoded a 362-amino-acids protein,whose molecular weight was predicted to 41.522kD and the isoelectric point of the protein was 5.60.The S1MYB102 was suggested to be a hydrophilic protein as the GRAVY is-0.746.Secondary structure prediction showed that the protein has 16.9%alpha helix,0.6%beta folding and 82.6%random coil.Experimental research showed that the protein was localized in the nucleus and had transcriptional activation activity.Quantitative Real-time PCR was used to detect the expression of SlMYB102 in root,stem,leaf,flower and fruit.This result showed that SIMYB102 was expressed in all the detected tissues and was higher in stem,leaf and flower,indicating that SlMYB102 may play a major role in stem,leaf and flower.To verify the function of SlMYB102,agrobacterium mediated genetic transformation was used to transform 35S:SlMYB102 vector into Micro-Tom.Three transgenic lines were obtained by PCR verification.Two lines(OE-1 and OE-2)with much higher gene expression were chosen for further study.Seed germination assay revealed that the seed germination of OE lines were faster than that of the wild type.This result indicated that SIMYB102 may involve in the regulation of seed germination.The plant height of wild type and OE lines were measured at seedlings and the first inflorescence period and found that the plant height of OE lines were significantly lower than that of the wild type.These results showed that overexpressing SIMYB102 gene may inhibit the growth of plants.To verify the function of SIMYB102 in salt resistance,the expression of SIMYB102 and other genes related to salt stress response signal transduction were detected in wild type and OE lines under NaCl treatment with different treating times.Results showed that the transcriptional level of detected genes in OE lines were higher than in wild type after 24h NaCl treatment,which further demonstrated that SIMYB102 involved in salt response.Compared with the untreated lines,the plant height of wild type and OE lines were all decreased under NaCl treatment.However,the plant height of the OE and wild type treated lines were similar,indicating that overexpressing SIMYB102 can reduce the injury of salt stress on plants.In addition,the proline content and the activity of antioxidant enzymes were tested under NaCl treatment after 10 days and found that they all higher in OE lines than in WT.These results suggested that SIMYB102 could improve the plant tolerance to salt.Overall,our results indicated that overexpressing a tomato R2R3MYB gene SIMYB102 could increase the plant salt tolerance which provides a good theoretical basis for breeding salt-tolerant tomato.