title: Overexpression of PIP2;5 aquaporin alleviates effects of low root temperature on cell hydraulic conductivity and growth in Arabidopsis.
abstract: The effects of low root temperature on growth and root cell water transport were compared between wild-type Arabidopsis (Arabidopsis thaliana) and plants overexpressing plasma membrane intrinsic protein 1;4 (PIP1;4) and PIP2;5. Descending root temperature from 25°C to 10°C quickly reduced cell hydraulic conductivity (L(p)) in wild-type plants but did not affect L(p) in plants overexpressing PIP1;4 and PIP2;5. Similarly, when the roots of wild-type plants were exposed to 10°C for 1 d, L(p) was lower compared with 25°C. However, there was no effect of low root temperature on L(p) in PIP1;4- and PIP2;5-overexpressing plants after 1 d of treatment. When the roots were exposed to 10°C for 5 d, L(p) was reduced in wild-type plants and in plants overexpressing PIP1;4, whereas there was still no effect in PIP2;5-overexpressing plants. These results suggest that the gating mechanism in PIP1;4 may be more sensitive to prolonged low temperature compared with PIP2;5. The reduction of L(p) at 10°C in roots of wild-type plants was partly restored to the preexposure level by 5 mm Ca(NO(3))(2) and protein phosphatase inhibitors (75 nm okadaic acid or 1 μm Na(3)VO(4)), suggesting that aquaporin phosphorylation/dephosphorylation processes were involved in this response. The temperature sensitivity of cell water transport in roots was reflected by a reduction in shoot and root growth rates in the wild-type and PIP1;4-overexpressing plants exposed to 10°C root temperature for 5 d. However, low root temperature had no effect on growth in plants overexpressing PIP2;5. These results provide strong evidence for a link between growth at low root temperature and aquaporin-mediated root water transport in Arabidopsis.
authors.affiliation: Department of Renewable Resources, University of Alberta, T6G 2E3 Edmonton, Alberta, Canada.
authors.forename: Seong Hee
authors.initials: SH
authors.lastname: Lee
authors.forename: Gap Chae
authors.initials: GC
authors.lastname: Chung
authors.forename: Ji Young
authors.initials: JY
authors.lastname: Jang
authors.forename: Sung Ju
authors.initials: SJ
authors.lastname: Ahn
authors.forename: Janusz J
authors.initials: JJ
authors.lastname: Zwiazek
mesh_terms: D020346:Aquaporins / Q000235:genetics / Q000378:metabolism*; D017360:Arabidopsis / Q000235:genetics / Q000254:growth & development* / Q000378:metabolism; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D001692:Biological Transport; D002462:Cell Membrane / Q000235:genetics / Q000378:metabolism; D002463:Cell Membrane Permeability; D003080:Cold Temperature; D018506:Gene Expression Regulation, Plant; D017343:Genes, Plant; D008627:Mercuric Chloride / Q000494:pharmacology; D018517:Plant Roots / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D018520:Plant Shoots / Q000502:physiology; D013312:Stress, Physiological; D013997:Time Factors; D014867:Water / Q000502:physiology
chemical_list: D020346:Aquaporins; D029681:Arabidopsis Proteins; C491680:plasma membrane intrinsic protein 2 Arabidopsis; D014867:Water; D008627:Mercuric Chloride