AUTHOR=Diehn Till A. , Pommerrenig Benjamin , Bernhardt Nadine , Hartmann Anja , Bienert Gerd P. 

TITLE=Genome-wide identification of aquaporin encoding genes in Brassica oleracea and their phylogenetic sequence comparison to Brassica crops and Arabidopsis

JOURNAL=Frontiers in Plant Science

VOLUME=6

YEAR=2015

URL=https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2015.00166

DOI=10.3389/fpls.2015.00166

ISSN=1664-462X

ABSTRACT=<p>Aquaporins (AQPs) are essential channel proteins that regulate plant water homeostasis and the uptake and distribution of uncharged solutes such as metalloids, urea, ammonia, and carbon dioxide. Despite their importance as crop plants, little is known about AQP gene and protein function in cabbage (<italic>Brassica oleracea</italic>) and other <italic>Brassica</italic> species. The recent releases of the genome sequences of <italic>B. oleracea</italic> and <italic>Brassica rapa</italic> allow comparative genomic studies in these species to investigate the evolution and features of <italic>Brassica</italic> genes and proteins. In this study, we identified all AQP genes in <italic>B. oleracea</italic> by a genome-wide survey. In total, 67 genes of four plant AQP subfamilies were identified. Their full-length gene sequences and locations on chromosomes and scaffolds were manually curated. The identification of six additional full-length AQP sequences in the <italic>B. rapa</italic> genome added to the recently published AQP protein family of this species. A phylogenetic analysis of AQPs of <italic>Arabidopsis thaliana</italic>, <italic>B. oleracea</italic>, <italic>B. rapa</italic> allowed us to follow AQP evolution in closely related species and to systematically classify and (re-) name these isoforms. Thirty-three groups of AQP-orthologous genes were identified between <italic>B. oleracea</italic> and <italic>Arabidopsis</italic> and their expression was analyzed in different organs. The two selectivity filters, gene structure and coding sequences were highly conserved within each AQP subfamily while sequence variations in some introns and untranslated regions were frequent. These data suggest a similar substrate selectivity and function of <italic>Brassica</italic> AQPs compared to <italic>Arabidopsis</italic> orthologs. The comparative analyses of all AQP subfamilies in three Brassicaceae species give initial insights into AQP evolution in these taxa. Based on the genome-wide AQP identification in <italic>B. oleracea</italic> and the sequence analysis and reprocessing of <italic>Brassica</italic> AQP information, our dataset provides a sequence resource for further investigations of the physiological and molecular functions of <italic>Brassica</italic> crop AQPs.</p>