| 研究実績の概要 |
Arabinogalactan proteins (AGPs) are functionally diverse cell wall structural glycoproteins that have been implicated in cell wall remodelling, though the mechanistic actions remain elusive. Here we demonstrate that novel AGP-like glycoproteins, SLEEPING BEAUTY (SB) and SB-like (SBL) negatively regulate the gametophore morphogenesis in Physcomitrium patens by dampening cell wall loosening/softening. The SB function is glycosylation-dependent and genetically connected with class C auxin response factor (ARF) transcription factors. We performed RNAseq analyses using an ARFC-inducible line to identify ARFC transcriptional targets AND Gene ontology analyses showed that cell wall-related GO terms were highly enriched. Specifically, there was a global downregulation of cell wall remodeling-related genes such as pectin methylesterases and expansins, suggesting that ARFC may directly suppresses these targets to inhibit cell expansion. Consistent with the suppressive role of ARFC in cell wall loosening, the ARFC overexpressor cells failed to expand and exhibited loss of polarized growth. Together our data revealed a novel inhibitory role of the putative AGP-ARFC signaling module to dampen cell wall loosening. We propose that AGP may act as a cell wall structural protein that senses changes in cell wall compositions and relay such information through ARFC to control cell wall remodeling.
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