How do proteoglycans mediate auxin gradient sensing in planar cell polarity?

2021 Fiscal Year Final Research Report

• Project/Area Number: 19K06701
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 44030:Plant molecular biology and physiology-related
• Research Institution: Hokkaido University
• Principal Investigator: Teh Ooi Kock 北海道大学, 高等教育推進機構, 助教 (80791277)
• Co-Investigator(Kenkyū-buntansha): 藤田 知道 北海道大学, 理学研究院, 教授 (50322631)
• Project Period (FY): 2019-04-01 – 2022-03-31
• Keywords: Physcomitrium patens / Proteoglycans / Cell wall

Outline of Final Research Achievements

We found that SB plays an inhibitory role in cell wall loosening. SB overexpression inhibits cell expansion while knocking out SB and its functional paralog, SB-like, accelerated gametophore initiation, an indication of loosen cell walls. Mutations analysis on the SB indicated that glycosylations are required for SB functions but has no effect on the SB subcellular localization. We further established a link between SB and a C-type auxin response factor (AFRC) by showing that SB positively regulated the expression level of ARFC. Furthermore, arfc loss-of-function mutants phenocopied sb and repressed the SB overexpressor phenotype, demonstrating that ARFC is acting downstream of SB. We performed RNAseq analyses using an ARFC-inducible line to identify ARFC transcriptional targets. Gene ontology (GO) analyses showed that cell wall-related GO terms were highly enriched. We propose that AGP may act as a cell wall structural protein that senses changes in cell wall compositions.

Free Research Field

Developmental biology

Academic Significance and Societal Importance of the Research Achievements

Our finding points to a previously unknown role of proteoglycan in sensing the cell wall changes. This knowledge has a potential to be applied in the agricultural sector to manipulate cell wall compositions for efficient biofuel production.