| TCP (TEOSINTE BRANCHED1, CYCLOIDEA, and PCF) gene family is a group of transcription factors identified specifically in plant genome, and is widely distributed in high plant species. This gene family is crucial for plant growth and development. There are totally24TCP genes in Arabidopsis genome. Based on sequence homology, these genes were classified into two groups named as class I and class Ⅱ. Class I contains13members whereas class II contains11members. Previous studies indicated that TCP1can interact with the promoter region of DWF4, a gene encoding a key enzyme in BR biosynthesis. Detailed analysis indicated that TCP1can positively regulate the transcription of DWF4. Due to functional redundancy among TCP family members, null mutants of TCP1do not show any defective phenotypes. We screened all TCP genes with chimeric repressor silencing technology (CREST) in order to find those possessing redundant roles with TCP1in regulating the BR biosynthetic pathway.We constructed dominant negative versions of TCPs, TCPs-SRDX for all24TCP members and found that TCP11-SRDX transgenic plants showed obvious phenotypes including dwarfed stem, delayed development. Histochemical staining analysis showed that TCP11is mainly expressed in developing vascular bundles. Stem transaction analysis found that TCP11-SRDX transgenic plants have fewer thicken xylem cells, and in some severe mutants no metaxylem was observed. The metaxylem phenotype is positively correlated to the expression levels of TCP11-SRDX. On the other hand, plants overexpressing TCP11showed inhomogeneous development of vascular bundles, suggesting that TCP11regulates the development of vascular bundles in Arabidopsis.To identify the downstream genes of TCP11, we sequenced the transcriptome of TCP11-SRDX, and found the expression levels of SEP3and VND7are upregulated. Our preliminary data indicated that TCP11may control the expression of SEP3and VND7to regulate the development of vascular bundles. |
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