Insights intoPopulusXIP aquaporins evolutionary expansion, protein functionality, and environmental regulation

• Published in: Journal of experimental botany Vol. 63; no. 5; pp. 2217 - 2230
• Main Authors: Lopez, D., Bronner, G., Brunel, N., Auguin, D., Bourgerie, S., Brignolas, F., Carpin, S., Tournaire-Roux, C., Maurel, C., Fumanal, B., Martin, F., Sakr, S., Label, P., Julien, J.L., Gousset-Dupont, A., Venisse, J.S.
• Format: Journal Article
• Language: English
• Published: Oxford University Press 01-01-2012
• Subjects: Amino acids; Angiosperms; Aquaporins; Genes; Genomes; Leaves; Oocytes; Phylogenetics; Plants; RESEARCH PAPER; Stems
• ISSN: 0022-0957; 1460-2431

A novel category of major intrinsic proteins which share weak similarities with previously identified aquaporin subfamilies was recently identified in land plants, and named X (for unrecognized) intrinsic proteins (XIPs). Because XIPs are still ranked as uncharacterized proteins, their further molecular characterization is required. Herein, a systematic fine-scale analysis of XIP sequences found in flowering plant databases revealed that XIPs are found in at least five groups. The phylogenetic relationship of these five groups with the phylogenetic organization of angiosperms revealed an original pattern of evolution for the XIP subfamily through distinct angiosperm taxon-specific clades. Of all flowering plant having XIPs, the genusPopulusencompasses the broadest panel and the highest polymorphism of XIP isoforms, with ninePtXIP sequences distributed within three XIP groups. ComprehensivePtXIPgene expression patterns showed that only two isoforms (PtXIP2;1andPtXIP3;2) were transcribed in vegetative tissues. However, their patterns are contrasted,PtXIP2;1was ubiquitously accumulated whereasPtXIP3;2was predominantly detected in wood and to a lesser extent in roots. Furthermore, onlyPtXIP2;1 exhibited a differential expression in leaves and stems of drought-, salicylic acid-, or wounding-challenged plants. Unexpectedly, thePtXIPs displayed different abilities to alter water transport upon expression inXenopus laevisoocytes.PtXIP2;1 andPtXIP3;3 transported water while other PtXIPs did not.