Abstract
Both the presence of, and the important contribution to growth and development made by TCP transcription factors, have been established in various plant species. Here, a TCP4 homolog isolated from Chrysanthemum nankingense was shown to be more strongly transcribed in the diploid than in the autotetraploid form of the species. CnTCP4 was shown to encode a member of the class II TCP family and to be transcribed most strongly in the leaf and ligulate flowers. Its transcription was found to be substantially inhibited by spraying the plant with the synthetic cytokinin 6-benzylaminopurine. The transient expression of CnTCP4 in onion epidermal cells showed that its product localized to the nucleus, and a yeast one hybrid assay suggested that its product had transcriptional activation ability. The constitutive expression of CnTCP4 in fission yeast suppressed cell proliferation, inducing the formation of longer and a higher frequency of multinuclated cells. Its constitutive expression in Arabidopsis thaliana reduced the size of the leaves. The presence of the transgene altered the transcription of a number of cell division-related genes. A yeast one hybrid assay identified a second TCP gene (CnTCP2) able to interact with the CnTCP4 promoter. A transient expression experiment in Nicotiana benthamiana leaves showed that CnTCP2 was able to activate the CnTCP4 promoter. Like CnTCP4, CnTCP2 was shown to encode a member of the class II TCP family, to be transcribed most strongly in the leaf and ligulate flowers, and to be suppressed by exogenous 6-benzylaminopurine treatment. The CnTCP2 protein also localized to the nucleus, but had no transcriptional activation ability. Its constitutive expression in A. thaliana had similar phenotypic consequences to those induced by CnTCP4.
Highlights
Development in a multicellular organism requires precise control over cell proliferation and expansion
The sequence was related to the class II set of TCP proteins, as its most closely related sequence was the product of AtTCP4 (Figure 1d)
A quantitative real-time PCR (qRT-PCR) experiment revealed that the abundance of CnTCP4 transcript was greater in the leaf of the diploid form of C. nankingense than in the leaf of the autotetraploid form (Figure 1a)
Summary
Development in a multicellular organism requires precise control over cell proliferation and expansion. The characteristic feature of the TCPs is a 59 residue stretch, which forms the basic helix-loop-helix (bHLH) motif central to the proteins’ ability to bind to DNA and to direct protein–protein interactions [5]. Both the Arabidopsis thaliana and rice genomes harbor over 20 genes encoding a TCP [6]. Based on variation in the TCP domain sequence, the TCPs have been divided into two distinct classes, referred to as class I/PCF/TCP-P and class II/TCP-C [7,8] While the former act to promote cell division, the latter repress it [6,9]. The experiments reported here were designed to reveal the transcriptional behavior of CnTCP4 in both diploid and autotetraploid forms of the species, and to study the phenotypic effect of heterologously expressing it in both fission yeast and A. thaliana
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
