Identification Of Cytokinin Two-component System Genes In Jiaobai(Zizania Latifolia Turcz.)and Analysis Of The TCS Gene Expression During Jiaobai Swelling

Cytokinins(CTKs),a kind of plant hormones that are mainly distributed in young tissues of plants,such as the apical stem.They have effects on plants' growth and development by promoting cell growth and elongation,which caused cell division or cytokinesis in plant roots and shoots.Previous studies have shown that CTK plays a major role in the swelling of jiaobai,the two-component system(TCS)signal transduction of CTK is a "phosphorelay" process,and it is generally believed that in plants is similar to bacteria's TCS process.It plays an important role in the growth and development of plants such as cell morphogenesis,signal transduction,and response to environmental stress.Jiaobai(Zizania latifolia Turcz.),as a unique aquatic vegetables in China,developed rapidly in recent years.However,the basic researches in Jiaobai have been lagging behind seriously.We still know very little about the mechanism of Jiaobai swelling.With the completion of whole genome sequencing of many species,more and more species of plants such as Arabidopsis,rice,and etc.have been reported in their TCS signal transduction mechanisms of CTK,while Jiaobai's is not yet.In this study,"Zhejiao No.2" was used as the experiment materials,we use cell biology,bioinformatics,and molecular biology to elucidate the mechanism that TCS signal transduction of CTK regulate jiaobai swelling.The results show that the main factor of promoting jiaobai swelling may be caused by cell growth.The treatment of exogenous trans-Zeatin might stimulate jiaobai swelling and increase the pregnancies rate of jiaobai.Besides,cell division is the main factor in the early enlargement periods,indicating that the CTK can promote jiaobai swelling through inducing cell division.Through the genome-wide analysis of the jiaobai,there were 56 proteins which were TCS homologous with Arabidopsis have been identified,including 13 Zl HKs,8 Zl HPs,and 35 Zl RRs of which 17 were A-type Z1 RRs,12 were B-type,2 were C-type,and 4 were Zl PRRs.We build phylogenetic tree to analysis the evolutionary relationship in jiaobai,rice and Arabidopsis,it was found that the evolutionary relationship between jiaobai and rice TCS signal transduction of CTK were more closer than that the Arabidopsis thaliana.We use the transcriptome sequencing technology of the jiaobai tissues at different stages of development(un-expansion,beginning of swelling and Lubai),combined with previous analysis of RNA-seq data,the results showed that fifty-one of the 56 TCS genes involved in the expression during the swelling process,and some genes changed significantly.Therefore,the six genes of Z1RR7,Z1RR8,Z1RR10,Zl HP5,Zl RR30 and Zl PRR2 may be involved in the process of jiaobai swelling process;With the RNA in situ hybridization analysis of Zl HP5 gene,Zl HP5 gene might express specifically on the vascular tube tissue when the jiaobai was in beginning of swelling stage.