title: Overexpression of a novel Arabidopsis PP2C isoform, AtPP2CF1, enhances plant biomass production by increasing inflorescence stem growth.
abstract: In contrast to mammals, higher plants have evolved to express diverse protein phosphatase 2Cs (PP2Cs). Of all Arabidopsis thaliana PP2Cs, members of PP2C subfamily A, including ABI1, have been shown to be key negative regulators of abscisic acid (ABA) signalling pathways, which regulate plant growth and development as well as tolerance to adverse environmental conditions. However, little is known about the enzymatic and signalling roles of other PP2C subfamilies. Here, we report a novel Arabidopsis subfamily E PP2C gene, At3g05640, designated AtPP2CF1. AtPP2CF1 was dramatically expressed in response to exogenous ABA and was expressed in vascular tissues and guard cells, similar to most subfamily A PP2C genes. In vitro enzymatic activity assays showed that AtPP2CF1 possessed functional PP2C activity. However, yeast two-hybrid analysis revealed that AtPP2CF1 did not interact with PYR/PYL/RCAR receptors or three SnRK2 kinases, which are ABI1-interacting proteins. This was supported by homology-based structural modelling demonstrating that the putative active- and substrate-binding site of AtPP2CF1 differed from that of ABI1. Furthermore, while overexpression of ABI1 in plants induced an ABA-insensitive phenotype, Arabidopsis plants overexpressing AtPP2CF1 (AtPP2CF1oe) were weakly hypersensitive to ABA during seed germination and drought stress. Unexpectedly, AtPP2CF1oe plants also exhibited increased biomass yield, mainly due to accelerated growth of inflorescence stems through the activation of cell proliferation and expansion. Our results provide new insights into the physiological significance of AtPP2CF1 as a candidate gene for plant growth production and for potential application in the sustainable supply of plant biomass.
authors.affiliation: Biotechnology Laboratory, Frontier Research Center, Toyota Central R&D Labs. Inc., 41-1, Yokomichi, Nagakute, Aichi 480-1192, Japan.
authors.forename: Hiroki
authors.initials: H
authors.lastname: Sugimoto
authors.affiliation: Bio Research Laboratory, Toyota Motor Corporation, 1, Toyota-cho, Toyota 471-8572, Japan.
authors.forename: Satoshi
authors.initials: S
authors.lastname: Kondo
authors.affiliation: Biotechnology Laboratory, Frontier Research Center, Toyota Central R&D Labs. Inc., 41-1, Yokomichi, Nagakute, Aichi 480-1192, Japan.
authors.forename: Tomoko
authors.initials: T
authors.lastname: Tanaka
authors.affiliation: Biotechnology Laboratory, Frontier Research Center, Toyota Central R&D Labs. Inc., 41-1, Yokomichi, Nagakute, Aichi 480-1192, Japan.
authors.forename: Chie
authors.initials: C
authors.lastname: Imamura
authors.affiliation: Biotechnology Laboratory, Frontier Research Center, Toyota Central R&D Labs. Inc., 41-1, Yokomichi, Nagakute, Aichi 480-1192, Japan.
authors.forename: Nobuhiko
authors.initials: N
authors.lastname: Muramoto
authors.affiliation: Bio Research Laboratory, Toyota Motor Corporation, 1, Toyota-cho, Toyota 471-8572, Japan.
authors.forename: Etsuko
authors.initials: E
authors.lastname: Hattori
authors.affiliation: Research Institute for Biological Sciences (RIBS), Kibichuo-cho, Okayama 716-1241, Japan.
authors.forename: Ken'ichi
authors.initials: K
authors.lastname: Ogawa
authors.affiliation: Biotechnology Laboratory, Frontier Research Center, Toyota Central R&D Labs. Inc., 41-1, Yokomichi, Nagakute, Aichi 480-1192, Japan Bio Research Laboratory, Toyota Motor Corporation, 1, Toyota-cho, Toyota 471-8572, Japan mitsukawa@mosk.tytlabs.co.jp.
authors.forename: Norihiro
authors.initials: N
authors.lastname: Mitsukawa
authors.affiliation: Bio Research Laboratory, Toyota Motor Corporation, 1, Toyota-cho, Toyota 471-8572, Japan.
authors.forename: Chikara
authors.initials: C
authors.lastname: Ohto
mesh_terms: D017360:Arabidopsis / Q000235:genetics / Q000254:growth & development* / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D018533:Biomass; D049109:Cell Proliferation / Q000502:physiology; D018506:Gene Expression Regulation, Plant; D056626:Inflorescence / Q000235:genetics / Q000254:growth & development* / Q000378:metabolism*
chemical_list: D029681:Arabidopsis Proteins
keywords: ABA (abscisic acid); PP2C.; biomass; cell proliferation and expansion; inflorescence stem; plant