Actin cytoskeleton and plasma membrane aquaporins are involved in different drought response of Arabidopsis rhd2 and der1 root hair mutants

Authors: TAKAC, TOMAS - Palacky University; KUBENOVA, LENKA - Palacky University; SAMAJOVA, OLGA - Palacky University; DVORAK, PETR - Palacky University; REHAK, JAN - Palacky University; HABERLAND, JAN - Palacky University; BUNDSCHUH, SEBASTIAN - Max Planck Institute Of Molecular Cell Biology And Genetics; PECHAN, TIBOR - Mississippi State University; TOMANACAK, PAVEL - Max Planck Institute Of Molecular Cell Biology And Genetics; OVECKA, MIROSLAV - Mississippi State University; SAMAJ, JOZEF - Palacky University

Submitted to: Plant Physiology and Biochemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/19/2024
Publication Date: 11/1/2024
Citation: Takac, T., Kubenova, L., Samajova, O., Dvorak, P., Rehak, J., Haberland, J., Pechan, T., Ovecka, M., Samaj, J. 2024. Actin cytoskeleton and plasma membrane aquaporins are involved in different drought response of Arabidopsis rhd2 and der1 root hair mutants. Plant Physiology and Biochemistry. https://doi.org/10.1016/j.plaphy.2024.109137.
DOI: https://doi.org/10.1016/j.plaphy.2024.109137

Interpretive Summary: We conducted a differential proteomic analysis of Arabidopsis rhd2-1 and der1-3 mutants. Both mutant types result in root hair defects associated with substantial alterations in abundances of stress-related proteins. Notably, plasma membrane (PM)-localized PIP aquaporins showed contrasting abundance patterns in the mutants compared to wild-types. Drought-responsive proteins were mostly downregulated in rhd2-1 but upregulated in der1-3. Proteomic data suggest that opposite to der1-3, altered vesicular transport in rhd2-1 mutant likely contributes to the deregulation of PM-localized proteins, including PIPs. Moreover, lattice light sheet microscopy revealed reduced actin dynamics in rhd2-1 roots, a finding contrasting with previous reports on der1-3 mutant. Phenotypic experiments demonstrated a drought stress susceptibility in rhd2-1 and resistance in der1-3. Thus, mutations in AtRBOHC/RHD2 and ACTIN2 cause similar root hair defects, but they differently affect the actin cytoskeleton and vesicular transport. Reduced actin dynamics in rhd2-1 mutant is accompanied by alteration of vesicular transport proteins abundance, likely leading to altered protein delivery to PM, including aquaporins, thereby significantly affecting drought stress responses.

Technical Abstract: Actin cytoskeleton and reactive oxygen species are principal determinants of root hair polarity and tip growth. Loss of function in RESPIRATORY BURST OXIDASE HOMOLOG C/ROOT HAIR DEFECTIVE 2 (AtRBOHC/RHD2), an NADPH oxidase emitting superoxide to the apoplast, and in ACTIN 2, a vegetative actin isovariant, in rhd2-1 and der1-3 mutants, respectively, lead to similar defects in root hair formation and elongation Since early endosome-mediated polar localization of AtRBOHC/RHD2 depends on actin cytoskeleton, comparing the proteome-wide consequences of both mutations might be of eminent interest. Therefore, we employed a differential proteomic analysis of Arabidopsis rhd2-1 and der1-3 mutants. Both mutants exhibited substantial alterations in abundances of stress-related proteins. Notably, plasma membrane (PM)-localized PIP aquaporins showed contrasting abundance patterns in the mutants compared to wild-types. Drought-responsive proteins were mostly downregulated in rhd2-1 but upregulated in der1-3. Proteomic data suggest that opposite to der1-3, altered vesicular transport in rhd2-1 mutant likely contributes to the deregulation of PM-localized proteins, including PIPs. Moreover, lattice light sheet microscopy revealed reduced actin dynamics in rhd2-1 roots, a finding contrasting with previous reports on der1-3 mutant. Phenotypic experiments demonstrated a drought stress susceptibility in rhd2-1 and resistance in der1-3. Thus, mutations in AtRBOHC/RHD2 and ACTIN2 cause similar root hair defects, but they differently affect the actin cytoskeleton and vesicular transport. Reduced actin dynamics in rhd2-1 mutant is accompanied by alteration of vesicular transport proteins abundance, likely leading to altered protein delivery to PM, including aquaporins, thereby significantly affecting drought stress responses.