title: Plasma membrane H(+) -ATPase gene expression, protein level and activity in growing and non-growing regions of barley (Hordeum vulgare) leaves.
abstract: Plasma membrane proton ATPase (PM-H⁺-ATPase) is the key means through which plant cells energize nutrient uptake and acidify the apoplast. Both of these processes aid cell elongation; yet, it is not known how such a suspected role of the PM-H⁺-ATPase in growth is reflected through changes in its transcript level and activity in grass leaves. In the present study on leaf three of barley, the elongation zone and the emerged blade, which contained fully expanded cells were analyzed. Plasma membranes were isolated and used to assay the activity (ATPase assay) and abundance (western blotting) of PM-H⁺-ATPase protein. Expression of mRNA was quantified using real-time polymerase chain reaction (qPCR). PM-H⁺-ATPase transcript and protein level and activity differed little between growing and non-growing leaf regions when values were related to unit extracted total RNA and cell number, respectively. However, when values were related to unit surface area of plasma membrane, they were more than twice as high in growing compared with non-growing leaf tissue. It is concluded that this higher surface density of PM-H⁺-ATPase activity in growing barley leaf tissue aids apoplast acidification and cell expansion.
authors.affiliation: Science Centre West, School of Biology and Environmental Science, University College Dublin, Belfield, Dublin 4, Ireland.
authors.forename: Tamás
authors.initials: T
authors.lastname: Visnovitz
authors.forename: Adám
authors.initials: A
authors.lastname: Solti
authors.forename: György
authors.initials: G
authors.lastname: Csikós
authors.forename: Wieland
authors.initials: W
authors.lastname: Fricke
mesh_terms: D002462:Cell Membrane / Q000201:enzymology*; D048429:Cell Size; D018076:DNA, Complementary / Q000235:genetics; D015971:Gene Expression Regulation, Enzymologic / Q000235:genetics; D018506:Gene Expression Regulation, Plant / Q000235:genetics; D001467:Hordeum / Q000201:enzymology* / Q000235:genetics / Q000254:growth & development; D018515:Plant Leaves / Q000201:enzymology* / Q000235:genetics / Q000254:growth & development; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism; D006180:Proton-Translocating ATPases / Q000235:genetics / Q000378:metabolism*; D011523:Protoplasts; D018749:RNA, Plant / Q000235:genetics; D014867:Water / Q000032:analysis / Q000378:metabolism
chemical_list: D018076:DNA, Complementary; D010940:Plant Proteins; D018749:RNA, Plant; D014867:Water; D006180:Proton-Translocating ATPases