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Updated: Feb 11, 2026

Live Imaging of Arabidopsis Pollen Tube Reception and Double Fertilization Using the Semi-In Vitro Cum Septum Method
Published on: February 24, 2023
CORNICHON sorting and regulation of GLR channels underlie pollen tube Ca2+ homeostasis
Michael M Wudick1,2, Maria Teresa Portes1,2, Erwan Michard1,2
1University of Maryland Department of Cell Biology and Molecular Genetics, 0118 Bioscience Research Building, 4066 Campus Drive, College Park, MD 20742-5815, USA.
Abstract:
Compared to animals, evolution of plant calcium (Ca2+) physiology has led to a loss of proteins for influx and small ligand-operated control of cytosolic Ca2+, leaving many Ca2+ mechanisms unaccounted for. Here, we show a mechanism for sorting and activation of glutamate receptor-like channels (GLRs) by CORNICHON HOMOLOG (CNIH) proteins. Single mutants of pollen-expressed Arabidopsis thaliana GLRs (AtGLRs) showed growth and Ca2+ flux phenotypes expected for plasma membrane Ca2+ channels. However, higher-order mutants of AtGLR3.3 revealed phenotypes contradicting this assumption. These discrepancies could be explained by subcellular AtGLR localization, and we explored the implication of AtCNIHs in this sorting. We found that AtGLRs interact with AtCNIH pairs, yielding specific intracellular localizations. AtCNIHs further trigger AtGLR activity in mammalian cells without any ligand. These results reveal a regulatory mechanism underlying Ca2+ homeostasis by sorting and activation of AtGLRs by AtCNIHs.
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