Preliminary Function Analysis Of PhTCP3and PhTCP4Genes In Petunia(Petunia Hybrida)

TCP genes are a special class of bHLH transcription factor family. BHLH domain have50-60amino acids, the amino acid is divided into two distinct parts:basic region length of10to15amino acids and40amino acids of α-helix-loop-α-helix area (HLH area). According to the characteristics of the structural domain, TCP gene family is divided into two subfamilies, class I and class II.With the differences of TCP structural domain, Class II is subdivided into two branches:ECE and CIN, and the branch of ECE contains three subclasses:CYC1, CYC2and CYC3,with roles in plant development and morphogenesis processes as diverse as the establishment of floral symmetry, plant architecture, leaf morphogenesis and senescence, embryo growth, and circadian rhythm. The CYC1class is mainly regulating plant branching.At present, the research of more CYC1support is BRC1in the MAX pathway involved in regulation of the growth of axillary bud, involved in auxin regulation of apical dominance and control branch development in Arabidopsis; the excessive expression of SIBRC1b gene plant branching decreased significantly, while the gene silencing phenotypes observed branching increased significantly in tomato; PsBRC1gene Mutants branch increased obviously in pea. Transcription factor PhTCP3and PhTCP4belong to CYC1class in petunia.In this paper, PhTCP3and PhTCP4gene were cloned from Mitchell Diploid(MD), then their expression was analyzed at the level of transcription., The interactions among PhTCP2, PhTCP3and PhTCP4protein in petunia were analyzed using the yeast two hybrid system. The function of PhTCP3and PhTCP4was studied by gene gene overexpression and silencing technology. The obtained research results are as follows:1Cloning of PhTCP3and PhTCP4in petuniaOn the basis of cDNA sequence of PhTCP3(GenBank accession number: JQ400106) and PhTCP4(GenBank accession number:JQ400107) gene downloaded from Genbank database, specific primers PT03F/PT03R and PT04F/PT04R are designed and synthesized.’MD’DNA sequence provides the template to perform amplification reactions, thereby full-length sequence of PhTCP3and PhTCP4are obtained.2The transcription analysis of PhTCP3and PhTCP4gene in petuniaThe expression quantity of PhTCP3and PhTCP4in different periods and tissues in MD are analyzed by means of fluorescence quantitative PCR.We found them specific express in the axillary bud, in other parts of the expression is very low. Expression of PhTCP3gene is bast in middle flower buds than small flower buds, big flower buds and fruits.However,while PhTCP4only in a small buds. Indicating that the two gene differences express in flower organ, density and auxin is response to the PhTCP3and PhTCP4gene. That regulation of PhTCP3and PhTCP4gene is involved in the growth of axillary bud.3Discuss the relationship among PhTCP2, PhTCP3, and PhTCP4in petuniaThe experiment shows that, PhTCP2, PhTCP3and PhTCP4protein can interact each other, PhTCP3and PhTCP4can interact with itself, and the fusion protein of BD-TCP2can not interact with fusion protein of AD-TCP2, AD-TCP3and AD-TCP4. BD-TCP2fusion protein has poisonous presumably.4Over expression and CREST silencing of PhTCP3and PhTCP4gene in petuniaOver expression and CREST silencing of PhTCP3gene phenotype are consistent with the wild type, suggesting that PhTCP3gene inhibite branching of function has disappeared in the evolutionary process. Overexpression of PhTCP4transgenic observed dormant axillary buds were compared with wild type, but after CREST silencing, axillary bud length was increased in the T1generation12leaf stage of petunia.