title: Genome-wide identification of aquaporin encoding genes in Brassica oleracea and their phylogenetic sequence comparison to Brassica crops and Arabidopsis.
abstract: 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 (Brassica oleracea) and other Brassica species. The recent releases of the genome sequences of B. oleracea and Brassica rapa allow comparative genomic studies in these species to investigate the evolution and features of Brassica genes and proteins. In this study, we identified all AQP genes in B. oleracea 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 B. rapa genome added to the recently published AQP protein family of this species. A phylogenetic analysis of AQPs of Arabidopsis thaliana, B. oleracea, B. rapa 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 B. oleracea and Arabidopsis 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 Brassica AQPs compared to Arabidopsis 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 B. oleracea and the sequence analysis and reprocessing of Brassica AQP information, our dataset provides a sequence resource for further investigations of the physiological and molecular functions of Brassica crop AQPs.
authors.affiliation: Metalloid Transport Group, Department of Physiology and Cell Biology, Leibniz Institute of Plant Genetics and Crop Plant Research, Gatersleben Germany.
authors.forename: Till A
authors.initials: TA
authors.lastname: Diehn
authors.affiliation: Metalloid Transport Group, Department of Physiology and Cell Biology, Leibniz Institute of Plant Genetics and Crop Plant Research, Gatersleben Germany.
authors.forename: Benjamin
authors.initials: B
authors.lastname: Pommerrenig
authors.affiliation: Experimental Taxonomy, Department of Genebank, Leibniz Institute of Plant Genetics and Crop Plant Research, Gatersleben Germany.
authors.forename: Nadine
authors.initials: N
authors.lastname: Bernhardt
authors.affiliation: Molecular Plant Nutrition, Department of Physiology and Cell Biology, Leibniz Institute of Plant Genetics and Crop Plant Research, Gatersleben Germany.
authors.forename: Anja
authors.initials: A
authors.lastname: Hartmann
authors.affiliation: Metalloid Transport Group, Department of Physiology and Cell Biology, Leibniz Institute of Plant Genetics and Crop Plant Research, Gatersleben Germany.
authors.forename: Gerd P
authors.initials: GP
authors.lastname: Bienert
keywords: Arabidopsis thaliana; Brassica oleracea; Brassica rapa; aquaporin; gene structure; major intrinsic protein; nodulin26-like intrinsic proteins; phylogeny