Cloning And Expression Characteristion Of Bolting And Flowering Genes SVP And SOC1 From Flowering Chinese Cabbage

Flowering Chinese cabbage(Brassica Campestris L.ssp.Chinesis var.utilis Tsenet Lee.)is an important vegetable in Cruciferae,and widely grown in south China.Stalk is the major produced organ of flowering Chinese cabbage,and normal bolting is a necessary condition for the stalk formation.In recent years,analysis on bolting and flowering mechanism of flowering Chinese cabbage has attracted much attentio n.In earlier research have shown that low temperature and gibberellin can promote bolting and flowering of flowering Chinese cabbage,but the molecular mechanisms are not known.SVP and SOC1 genes are important factors that can regulate multiple pathways of plant bolting and flowering,including ambient temperature pathway and gibberellin pathway.Therefore,two different maturing(early-maturing variety ?sijiu-19 hao‘ and lately-maturing variety ?youlv 80‘)of flowering Chinese cabbagewere used to experimental materials in this study,the molecular characterization of SVP and SOC1,the localization of their proteins,and expression patterns in different organs and upon gibberellin and low temperature treatment were investigated.The main results were as follows:1.Cloning BcSVP,BcSOC1-1and BcSOC1-2 genes from flowering Chinese cabbage and the full-length open reading frames of these three genes were 727 bp,642 bp and 642 bp,respectively.And BcSOC1-1 had the highest homologous identity with BcSOC1-2(95%).Phylogenetic tree analysis showed that BcSVP,BcSOC1-1 and BcSOC1-2 were close with other Cruciferae plant.Predicted the protein domain,motifs and secondary structure of these three genes by the amino acid sequences,and the result showed that these three genes function were conserved,and had the MADS-box and K-box,which were the typical domain of MADS family.2.The BcSVP,BcSOC1-1 and BcSOC1-2 genes were constructed the recombinant plasmids fused with EGFP and transformed into onion epidermis cells,the results showed that BcSVP and BcSOC1-2 were localized in nucleus,and BcSOC1-1 was localized in nucleus and cytoplasm.BcSVP,BcSOC1-1 and BcSOC1-2 genes were expressed in different tissues of flowering Chinese cabbage,include root,shoot tips,leaf and flower.BcSVP was highest expressed in leaves and shoot tips,BcSOC1-1 was highest expressed in shoot tips and followed in roots and leaves,and Bc SOC1-2 was highest expressed in roots and followed in shoot tips.In addition,these three genes were low expressed in flowers.3.Treated flowering Chinese cabbage with 200 mg/L gibberellins can significantly increased the plant height,reduce the stalk diameter,and advanced the bolting and flowering time.The relatively expression levels of BcSVP gene was higher before budding and lower after budding,on the contrary,BcSOC1-1 and BcSOC1-2 were remained steady at low levels before budding and increased after budding.Gibberellin treatment can decreased the expression levels of BcSVP,and increased BcSOC1-1 and BcSOC1-2 expressed.4.Low temperature(4℃ or 15℃)treatment can significantly promoting bolting and flowering of flowering Chinese cabbage,increased the plant height,and reduce the stalk diameter.Meanwhile,low temperature(4 ℃ or 15℃)can down-regulated the BcSVP expressed and up-regulated BcSOC1-1,BcSOC1-2 expressed compared to the 25 ℃treatment.In summary,gibberellins(200 mg/L)and low temperature(4 ℃ or 15 ℃)can significantly advance bolting and flowering time of flowering Chinese cabbage,and it may be regulated by down-regulated the expression levels of BcSVP and up-regulated the expression levels of BcSOC1-1,BcSOC1-2.