title: OSCA1 mediates osmotic-stress-evoked Ca2+ increases vital for osmosensing in Arabidopsis.
abstract: Water is crucial to plant growth and development. Environmental water deficiency triggers an osmotic stress signalling cascade, which induces short-term cellular responses to reduce water loss and long-term responses to remodel the transcriptional network and physiological and developmental processes. Several signalling components that have been identified by extensive genetic screens for altered sensitivities to osmotic stress seem to function downstream of the perception of osmotic stress. It is known that hyperosmolality and various other stimuli trigger increases in cytosolic free calcium concentration ([Ca(2+)]i). Considering that in bacteria and animals osmosensing Ca(2+) channels serve as osmosensors, hyperosmolality-induced [Ca(2+)]i increases have been widely speculated to be involved in osmosensing in plants. However, the molecular nature of corresponding Ca(2+) channels remain unclear. Here we describe a hyperosmolality-gated calcium-permeable channel and its function in osmosensing in plants. Using calcium-imaging-based unbiased forward genetic screens we isolated Arabidopsis mutants that exhibit low hyperosmolality-induced [Ca(2+)]i increases. These mutants were rescreened for their cellular, physiological and developmental responses to osmotic stress, and those with clear combined phenotypes were selected for further physical mapping. One of the mutants, reduced hyperosmolality-induced [Ca(2+)]i increase 1 (osca1), displays impaired osmotic Ca(2+) signalling in guard cells and root cells, and attenuated water transpiration regulation and root growth in response to osmotic stress. OSCA1 is identified as a previously unknown plasma membrane protein and forms hyperosmolality-gated calcium-permeable channels, revealing that OSCA1 may be an osmosensor. OSCA1 represents a channel responsible for [Ca(2+)]i increases induced by a stimulus in plants, opening up new avenues for studying Ca(2+) machineries for other stimuli and providing potential molecular genetic targets for engineering drought-resistant crops.
authors.affiliation: 1] Department of Biology, Duke University, Durham, North Carolina 27708, USA [2] Center on Plant Environmental Sensing, College of Life and Environmental Sciences, Hangzhou Normal University, Hangzhou, Zhejiang 310036, China.
authors.forename: Fang
authors.initials: F
authors.lastname: Yuan
authors.affiliation: 1] Department of Biology, Duke University, Durham, North Carolina 27708, USA [2].
authors.forename: Huimin
authors.initials: H
authors.lastname: Yang
authors.affiliation: 1] Department of Biology, Duke University, Durham, North Carolina 27708, USA [2].
authors.forename: Yan
authors.initials: Y
authors.lastname: Xue
authors.affiliation: Department of Biology, Duke University, Durham, North Carolina 27708, USA.
authors.forename: Dongdong
authors.initials: D
authors.lastname: Kong
authors.affiliation: Department of Biology, Duke University, Durham, North Carolina 27708, USA.
authors.forename: Rui
authors.initials: R
authors.lastname: Ye
authors.affiliation: Department of Biology, Duke University, Durham, North Carolina 27708, USA.
authors.forename: Chijun
authors.initials: C
authors.lastname: Li
authors.affiliation: 1] Department of Biology, Duke University, Durham, North Carolina 27708, USA [2] Center on Plant Environmental Sensing, College of Life and Environmental Sciences, Hangzhou Normal University, Hangzhou, Zhejiang 310036, China.
authors.forename: Jingyuan
authors.initials: J
authors.lastname: Zhang
authors.affiliation: Department of Biology, Duke University, Durham, North Carolina 27708, USA.
authors.forename: Lynn
authors.initials: L
authors.lastname: Theprungsirikul
authors.affiliation: Department of Biology, Duke University, Durham, North Carolina 27708, USA.
authors.forename: Tayler
authors.initials: T
authors.lastname: Shrift
authors.affiliation: Department of Biology, Duke University, Durham, North Carolina 27708, USA.
authors.forename: Bryan
authors.initials: B
authors.lastname: Krichilsky
authors.affiliation: Department of Physics, Duke University, Durham, North Carolina 27708, USA.
authors.forename: Douglas M
authors.initials: DM
authors.lastname: Johnson
authors.affiliation: Department of Physics, Duke University, Durham, North Carolina 27708, USA.
authors.forename: Gary B
authors.initials: GB
authors.lastname: Swift
authors.affiliation: Department of Biology, Duke University, Durham, North Carolina 27708, USA.
authors.forename: Yikun
authors.initials: Y
authors.lastname: He
authors.affiliation: Department of Biology, Duke University, Durham, North Carolina 27708, USA.
authors.forename: James N
authors.initials: JN
authors.lastname: Siedow
authors.affiliation: Department of Biology, Duke University, Durham, North Carolina 27708, USA.
authors.forename: Zhen-Ming
authors.initials: ZM
authors.lastname: Pei
mesh_terms: D017360:Arabidopsis / Q000235:genetics / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D002118:Calcium / Q000378:metabolism*; D015220:Calcium Channels / Q000235:genetics / Q000378:metabolism*; D020013:Calcium Signaling; D002462:Cell Membrane / Q000378:metabolism; D003593:Cytoplasm / Q000378:metabolism; D055864:Droughts; D057809:HEK293 Cells; D006801:Humans; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism; D009997:Osmotic Pressure; D018517:Plant Roots / Q000166:cytology / Q000254:growth & development / Q000378:metabolism; D018526:Plant Transpiration; D014867:Water / Q000378:metabolism*
chemical_list: D029681:Arabidopsis Proteins; D015220:Calcium Channels; D008565:Membrane Proteins; C000592922:OSCA1 protein, Arabidopsis; D014867:Water; D002118:Calcium