Abstract
In flowering plants, the switch from floral stem cell maintenance to gynoecium (female structure) formation is a critical developmental transition for reproductive success. In Arabidopsis thaliana, AGAMOUS (AG) terminates floral stem cell activities to trigger this transition. Although CRABS CLAW (CRC) is a direct target of AG, previous research has not identified any common targets. Here, we identify an auxin synthesis gene, YUCCA4 (YUC4) as a common direct target. Ectopic YUC4 expression partially rescues the indeterminate phenotype and cell wall defects that are caused by the crc mutation. The feed-forward YUC4 activation by AG and CRC directs a precise change in chromatin state for the shift from floral stem cell maintenance to gynoecium formation. We also showed that two auxin-related direct CRC targets, YUC4 and TORNADO2, cooperatively contribute to the termination of floral stem cell maintenance. This finding provides new insight into the CRC-mediated auxin homeostasis regulation for proper gynoecium formation.
Highlights
In flowering plants, the switch from floral stem cell maintenance to gynoecium formation is a critical developmental transition for reproductive success
We showed that two auxin-related CRABS CLAW (CRC) targets, YUC4 and TRN2 cooperatively function for floral meristem termination
Since the imitation switch (ISWI)-type chromatin remodeling factors CHROMATIN REMODELING 11 (CHR11) and CHR17 were identified as AG interacting partners and a chr[11] chr[17] double mutant showed a split style phenotype[55,56,57,58] (Supplementary Fig. 13), we examined the role of AG and CHR11/CHR17 in regulating YUC4
Summary
The switch from floral stem cell maintenance to gynoecium (female structure) formation is a critical developmental transition for reproductive success. We showed that two auxinrelated direct CRC targets, YUC4 and TORNADO2, cooperatively contribute to the termination of floral stem cell maintenance. This finding provides new insight into the CRC-mediated auxin homeostasis regulation for proper gynoecium formation. Auxin perception and signaling are controlled by auxin receptors, ubiquitin-ligase, and auxin-dependent transcriptional modules[26] Despite their potential impact on auxin homeostasis, auxin-related CRC targets, other than TRN2, have not been identified. We showed that two auxin-related CRC targets, YUC4 and TRN2 cooperatively function for floral meristem termination. Our results provide insight into the transcriptional cascades that govern the transition from floral stem cell maintenance to gynoecium formation
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