The WRKY Transcription Factor Family in Citrus: Valuable and Useful Candidate Genes for Citrus Breeding

• DOI: 10.1007/s12010-016-2114-8
• Publication Date: 2016-05-19T12:31:22Z
• Authors: M. Ayadi; M. Hanana; N. Kharrat; H. Merchaoui; R. Ben Marzoug; V. Lauvergeat; A. Rebaï; R. Mzid
• Keywords: 0301 basic medicine; Citrus; Amino Acid Motifs; Wrky; Genes, Plant; 630; Chromosomes, Plant; 03 medical and health sciences; Zinc Finger; Plant Growth Regulators; Protein Domains; Gene Expression Regulation, Plant; Stress, Physiological; Stress Tolerance; Régulateur de transcription; [SDV.BV]Life Sciences [q-bio]/Vegetal Biology; Cluster Analysis; Computer Simulation; Amino Acid Sequence; Conserved Sequence; Genetic Association Studies; Phylogeny; Plant Proteins; 580; Expressed Sequence Tags; 2. Zero hunger; Gene Expression Profiling; 15. Life on land; Séquençage du génome; Facteur de transcription; Essential Oil Biosynthesis; Plant Breeding; Multigene Family; Analyse phylogénétique; Duplication de gènes; Sequence Alignment; Fruit Acidification

WRKY transcription factors belong to a large family of plant transcriptional regulators whose members have been reported to be involved in a wide range of biological roles including plant development, adaptation to environmental constraints and response to several diseases. However, little or poor information is available about WRKY's in Citrus. The recent release of completely assembled genomes sequences of Citrus sinensis and Citrus clementina and the availability of ESTs sequences from other citrus species allowed us to perform a genome survey for Citrus WRKY proteins. In the present study, we identified 100 WRKY members from C. sinensis (51), C. clementina (48) and Citrus unshiu (1), and analyzed their chromosomal distribution, gene structure, gene duplication, syntenic relation and phylogenetic analysis. A phylogenetic tree of 100 Citrus WRKY sequences with their orthologs from Arabidopsis has distinguished seven groups. The CsWRKY genes were distributed across all ten sweet orange chromosomes. A comprehensive approach and an integrative analysis of Citrus WRKY gene expression revealed variable profiles of expression within tissues and stress conditions indicating functional diversification. Thus, candidate Citrus WRKY genes have been proposed as potentially involved in fruit acidification, essential oil biosynthesis and abiotic/biotic stress tolerance. Our results provided essential prerequisites for further WRKY genes cloning and functional analysis with an aim of citrus crop improvement.