title: TIP5;1 is an aquaporin specifically targeted to pollen mitochondria and is probably involved in nitrogen remobilization in Arabidopsis thaliana.
abstract: In plant sexual reproduction, water and solute movement are tightly regulated, suggesting the involvement of aquaporins. We previously identified TIP5;1 and TIP1;3 as the only Arabidopsis aquaporin genes that are selectively and highly expressed in mature pollen, and showed that they can transport both water and urea when expressed in Xenopus oocytes. Here, we show that TIP5;1 has unusual characteristics, as its water transport activity is regulated by pH. Analysis of the water transport activity of a mutant version of TIP5;1 (TIP5;1-H131A) and amino acid alignment with other plant aquaporins regulated by pH suggested that a conserved motif is involved in pH sensing. GFP-TIP5;1 is located in the mitochondria of pollen tubes. The single mutants tip1;3 and tip5;1, as well as the tip1;3 tip5;1 double mutant, are fertile, but all mutants had shorter than normal pollen tubes when germinated in vitro in the absence of exogenous nitrogen. Thus, we propose that TIP5;1 and TIP1;3 are involved in nitrogen recycling in pollen tubes of Arabidopsis thaliana.
authors.affiliation: Instituto de Ingeniería Genética y Biología Molecular (INGEBI-CONICET), Vuelta de Obligado 2490 Piso 2, 1428 Buenos Aires, Argentina.
authors.forename: Gabriela
authors.initials: G
authors.lastname: Soto
authors.forename: Romina
authors.initials: R
authors.lastname: Fox
authors.forename: Nicolas
authors.initials: N
authors.lastname: Ayub
authors.forename: Karina
authors.initials: K
authors.lastname: Alleva
authors.forename: Francisco
authors.initials: F
authors.lastname: Guaimas
authors.forename: Elizabeth Jares
authors.initials: EJ
authors.lastname: Erijman
authors.forename: Agustina
authors.initials: A
authors.lastname: Mazzella
authors.forename: Gabriela
authors.initials: G
authors.lastname: Amodeo
authors.forename: Jorge
authors.initials: J
authors.lastname: Muschietti
mesh_terms: D020346:Aquaporins / Q000235:genetics / Q000378:metabolism*; D017360:Arabidopsis / Q000235:genetics* / Q000378:metabolism; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D008928:Mitochondria / Q000235:genetics*; D016254:Mutagenesis, Insertional; D009584:Nitrogen / Q000378:metabolism*; D010802:Phylogeny; D053205:Pollen Tube / Q000235:genetics*; D018749:RNA, Plant / Q000235:genetics; D014867:Water / Q000378:metabolism
chemical_list: D020346:Aquaporins; D029681:Arabidopsis Proteins; D018749:RNA, Plant; C535169:TIP5;1 protein, Arabidopsis; D014867:Water; D009584:Nitrogen