title: Improved salinity tolerance of rice through cell type-specific expression of AtHKT1;1.
abstract: Previously, cell type-specific expression of AtHKT1;1, a sodium transporter, improved sodium (Na(+)) exclusion and salinity tolerance in Arabidopsis. In the current work, AtHKT1;1, was expressed specifically in the root cortical and epidermal cells of an Arabidopsis GAL4-GFP enhancer trap line. These transgenic plants were found to have significantly improved Na(+) exclusion under conditions of salinity stress. The feasibility of a similar biotechnological approach in crop plants was explored using a GAL4-GFP enhancer trap rice line to drive expression of AtHKT1;1 specifically in the root cortex. Compared with the background GAL4-GFP line, the rice plants expressing AtHKT1;1 had a higher fresh weight under salinity stress, which was related to a lower concentration of Na(+) in the shoots. The root-to-shoot transport of (22)Na(+) was also decreased and was correlated with an upregulation of OsHKT1;5, the native transporter responsible for Na(+) retrieval from the transpiration stream. Interestingly, in the transgenic Arabidopsis plants overexpressing AtHKT1;1 in the cortex and epidermis, the native AtHKT1;1 gene responsible for Na(+) retrieval from the transpiration stream, was also upregulated. Extra Na(+) retrieved from the xylem was stored in the outer root cells and was correlated with a significant increase in expression of the vacuolar pyrophosphatases (in Arabidopsis and rice) the activity of which would be necessary to move the additional stored Na(+) into the vacuoles of these cells. This work presents an important step in the development of abiotic stress tolerance in crop plants via targeted changes in mineral transport.
authors.affiliation: Australian Centre for Plant Functional Genomics, University of Adelaide, Glen Osmond, South Australia, Australia.
authors.forename: Darren
authors.initials: D
authors.lastname: Plett
authors.forename: Gehan
authors.initials: G
authors.lastname: Safwat
authors.forename: Matthew
authors.initials: M
authors.lastname: Gilliham
authors.forename: Inge
authors.initials: I
authors.lastname: Skrumsager Møller
authors.forename: Stuart
authors.initials: S
authors.lastname: Roy
authors.forename: Neil
authors.initials: N
authors.lastname: Shirley
authors.forename: Andrew
authors.initials: A
authors.lastname: Jacobs
authors.forename: Alexander
authors.initials: A
authors.lastname: Johnson
authors.forename: Mark
authors.initials: M
authors.lastname: Tester
mesh_terms: D017360:Arabidopsis / Q000235:genetics / Q000378:metabolism; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D001692:Biological Transport; D027682:Cation Transport Proteins / Q000235:genetics / Q000378:metabolism*; D015870:Gene Expression; D018506:Gene Expression Regulation, Plant; D009928:Organ Specificity; D012275:Oryza / Q000235:genetics / Q000502:physiology*; D018517:Plant Roots / Q000235:genetics / Q000378:metabolism; D030821:Plants, Genetically Modified / Q000235:genetics / Q000502:physiology*; D055049:Salt Tolerance; D012964:Sodium / Q000378:metabolism; D027981:Symporters / Q000235:genetics / Q000378:metabolism*
chemical_list: D029681:Arabidopsis Proteins; D027682:Cation Transport Proteins; C490286:HKT1 protein, Arabidopsis; D027981:Symporters; D012964:Sodium