The class I protein AtTCP15 modulates plant development through a pathway that overlaps with the one affected by CIN-like TCP proteins.

UBERTI-MANASSERO N; LUCERO L; VIOLA I.; VEGETTI A; GONZALEZ D

JOURNAL OF EXPERIMENTAL BOTANY

OXFORD UNIV PRESS

Año: 2012 vol. 63 p. 809 - 823

0022-0957

The function of the class I TCP transcription factor TCP15 from Arabidopsis thaliana has been studied through theanalysis of plants that express a fusion of this protein to the EAR repressor domain. Constitutive expression ofTCP15-EAR produces growth arrest at the seedling stage, before leaf emergence. Expression of the repressor fusionfrom the AtTCP15 promoter produces small plants with leaves whose margins progressively curve upwards, startingfrom the basal part of the lamina. Leaves contain smaller and less differentiated cells, both on the adaxial andabaxial 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 elongationof the three outer whorls and altered gynoecia with irregular carpel surfaces and enlarged repla. Ectopic stigma-likestructures develop from medial and basal parts of the replum. TCP15-EAR produces an increase in expression of theboundary-specific genes LOB, CUC1, and CUC2. Changes in CUC1 and CUC2 expression can be explained by theexistence of lower levels of miR164 in leaves and the repression of IAA3/SHY2 and the SAUR-like gene At1g29460 inleaves and flowers. TCP15 binds to the promoter regions of IAA3/SHY2 and At1g29460, suggesting that these genesmay be direct targets of the transcription factor. The results indicate that TCP15 regulates the expression ofboundary-specific genes through a pathway that affects auxin homeostasis and partially overlaps with the onemodulated by class II CIN-like TCP proteins.