Instituto de Agrobiotecnología del Litoral (CONICET-UNL), Cátedra de Biología Celular y Molecular, Facultad de Bioquímica y Ciencias Biológicas, Universidad Nacional del Litoral, CC 242 Paraje El Pozo, 3000 Santa Fe, Argentina.
J Exp Bot. 2012 Jan;63(2):809-23. doi: 10.1093/jxb/err305. Epub 2011 Oct 20.
The function of the class I TCP transcription factor TCP15 from Arabidopsis thaliana has been studied through the analysis of plants that express a fusion of this protein to the EAR repressor domain. Constitutive expression of TCP15-EAR produces growth arrest at the seedling stage, before leaf emergence. Expression of the repressor fusion from the AtTCP15 promoter produces small plants with leaves whose margins progressively curve upwards, starting from the basal part of the lamina. Leaves contain smaller and less differentiated cells, both on the adaxial and abaxial sides. The abaxial domain is relatively enlarged, with disorganized cells separated by empty spaces. TCP15-EAR also affects the growth of leaf petioles, flower pedicels, and anther filaments. Flowers show reduced elongation of the three outer whorls and altered gynoecia with irregular carpel surfaces and enlarged repla. Ectopic stigma-like structures develop from medial and basal parts of the replum. TCP15-EAR produces an increase in expression of the boundary-specific genes LOB, CUC1, and CUC2. Changes in CUC1 and CUC2 expression can be explained by the existence of lower levels of miR164 in leaves and the repression of IAA3/SHY2 and the SAUR-like gene At1g29460 in leaves and flowers. TCP15 binds to the promoter regions of IAA3/SHY2 and At1g29460, suggesting that these genes may be direct targets of the transcription factor. The results indicate that TCP15 regulates the expression of boundary-specific genes through a pathway that affects auxin homeostasis and partially overlaps with the one modulated by class II CIN-like TCP proteins.
拟南芥 I 类 TCP 转录因子 TCP15 的功能是通过分析表达该蛋白与 EAR 抑制结构域融合的植物来研究的。TCP15-EAR 的组成型表达导致幼苗期出现生长停滞，在出现叶片之前。从 AtTCP15 启动子表达抑制融合物会导致产生叶片逐渐向上卷曲的小植株，从叶片的基部开始。叶片包含更小和分化程度更低的细胞，无论是在近轴侧还是远轴侧。远轴域相对扩大，细胞排列不规则，有空隙隔开。TCP15-EAR 还影响叶片叶柄、花花梗和花药花丝的生长。花朵表现出三个外轮的伸长减少，并且雌蕊发生改变，具有不规则的心皮表面和扩大的胎座。从胎座的中部和基部发育出拟柱头样结构。TCP15-EAR 导致边界特异性基因 LOB、CUC1 和 CUC2 的表达增加。CUC1 和 CUC2 表达的变化可以通过叶片中 miR164 水平降低以及叶片和花朵中 IAA3/SHY2 和 SAUR 样基因 At1g29460 的抑制来解释。TCP15 结合到 IAA3/SHY2 和 At1g29460 的启动子区域，表明这些基因可能是转录因子的直接靶标。结果表明，TCP15 通过影响生长素稳态的途径调节边界特异性基因的表达，该途径与由类 II CIN 样 TCP 蛋白调节的途径部分重叠。
