AtTIP5;1 is a pollen specific mitochondrial tonoplast intrinsic protein involved in nitrogen mobilization in pollen

GABRIELA SOTO; ROMINA FOX; NICOLAS AYUB; KARINA ALLEVA; FRANCISCO GUAIMAS; ELIZABETH JARES; AGUSTINA MAZZELA; GABRIELA AMODEO; JORGE MUSCHIETTI

PLANT JOURNAL

WILEY-BLACKWELL PUBLISHING, INC

Lugar: London; Año: 2010 vol. 64 p. 1038 - 1047

0960-7412

Sexual reproduction involves processes where water and solute movement is finely regulated, suggesting the involvement of aquaporins. We previously identified AtTIP5;1 and AtTIP1,3 as the only aquaporin genes that are selectively and highly expressed in mature Arabidopsis pollen. Based on functional experiments using Xenoups oocytes, we showed that AtTIP5;1 and AtTIP1;3 are both water a urea transporters. In this work we found that AtTIP5;1 is a pollen aquaporin with unusual characteristics. AtTIP5;1 is the first member of the TIP subfamily whose water transport activity is regulated by pH. Amino acidic alignment of plant aquaporins regulated by pH revealed a conserved amino acidic motif potentially involved in pH sensing. Subcellular localization studies showed that AtTIP5;1 is expressed in the mitochondria of pollen tubes being the first evidence of a plant aquaporin with mitochondrial localization. Arabidopsis mutants tip1;3, tip5;1 and tip1;3 tip5;1 are fertile but showed, under nitrogen absence conditions, shorter pollen tubes compared to wild type tubes. Together, these results allowed us to propose a model about the mechanism of action of pollen aquaporins involved in nitrogen recycling in pollen.