MADS-Box and bHLH Transcription Factors Coordinate Transmitting Tract Development in Arabidopsis thaliana
Maurizio Di Marzo, Irma Roig‐Villanova, Eva Zanchetti, Francesca Caselli, Veronica Gregis, Paola Bardetti, Matteo Chiara, Andrea Guazzotti, Elisabetta Caporali, Marta Adelina Mendes, Lucia Colombo, Martin M. Kater
Abstract
The MADS-domain transcription factor SEEDSTICK (STK) controls several aspects of plant reproduction. STK is co-expressed with CESTA (CES), a basic Helix-Loop-Helix (bHLH) transcription factor-encoding gene. CES was reported to control redundantly with the brassinosteroid positive signaling factors BRASSINOSTEROID ENHANCED EXPRESSION1 (BEE1) and BEE3 the development of the transmitting tract. Combining the stk ces-2 mutants led to a reduction in ovule fertilization due to a defect in carpel fusion which, caused the formation of holes at the center of the septum where the transmitting tract differentiates. Combining the stk mutant with the bee1 bee3 ces-2 triple mutant showed a clear enhancement of the number of unfertilized ovules and septum defects. The transcriptome profile of this quadruple mutant revealed a small subset of deregulated genes which are mainly involved in cell death, extracellular matrix and cell wall development. Our data evidence a regulatory gene network controlling transmitting tract development regulated directly or indirectly by a STK-CES containing complex and reveal new insights in the regulation of transmitting tract development by bHLH and MADS-domain transcription factors.