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Rice actin-binding protein RMD is a key link in the auxin-actin regulatory loop that controls cell growth

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dc.contributor.authorLi, G.
dc.contributor.authorLiang, W.
dc.contributor.authorZhang, X.
dc.contributor.authorRen, H.
dc.contributor.authorHu, J.
dc.contributor.authorBennett, M.
dc.contributor.authorZhang, D.
dc.date.issued2014
dc.description.abstractThe plant hormone auxin plays a central role in plant growth and development. Auxin transport and signaling depend on actin organization. Despite its functional importance, the mechanistic link between actin filaments (F-actin) and auxin intracellular signaling remains unclear. Here, we report that the actin-organizing protein Rice Morphology Determinant (RMD), a type II formin from rice (Oryza sativa), provides a key link. Mutants lacking RMD display abnormal cell growth and altered configuration of F-actin array direction. The rmd mutants also exhibit an inhibition of auxin-mediated cell elongation, decreased polar auxin transport, altered auxin distribution gradients in root tips, and suppression of plasma membrane localization of auxin transporters O. sativa PIN-FORMED 1b (OsPIN1b) and OsPIN2 in root cells. We demonstrate that RMD is required for endocytosis, exocytosis, and auxin-mediated OsPIN2 recycling to the plasma membrane. Moreover, RMD expression is directly regulated by heterodimerized O. sativa auxin response factor 23 (OsARF23) and OsARF24, providing evidence that auxin modulates the orientation of F-actin arrays through RMD. In support of this regulatory loop, osarf23 and lines with reduced expression of both OsARF23 and OsARF24 display reduced RMD expression, disrupted F-actin organization and cell growth, less sensitivity to auxin response, and altered auxin distribution and OsPIN localization. Our findings establish RMD as a crucial component of the auxin-actin self-organizing regulatory loop from the nucleus to cytoplasm that controls rice cell growth and morphogenesis.
dc.description.statementofresponsibilityGang Li, Wanqi Liang, Xiaoqing Zhang, Haiyun Ren, Jianping Hu, Malcolm J. Bennett, and Dabing Zhang
dc.identifier.citationProceedings of the National Academy of Sciences of the United States of America, 2014; 111(28):10377-10382
dc.identifier.doi10.1073/pnas.1401680111
dc.identifier.issn0027-8424
dc.identifier.issn1091-6490
dc.identifier.orcidZhang, D. [0000-0003-3181-9812]
dc.identifier.urihttp://hdl.handle.net/2440/97457
dc.language.isoen
dc.publisherNational Academy of Sciences
dc.rightsCopyright status unknown
dc.source.urihttps://doi.org/10.1073/pnas.1401680111
dc.subjectauxin signaling
dc.subjectactin cytoskeleton
dc.subjectrice morphogenesis
dc.titleRice actin-binding protein RMD is a key link in the auxin-actin regulatory loop that controls cell growth
dc.typeJournal article
pubs.publication-statusPublished

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