Identification and Expression Profiles of the WRKY Gene Family in Pecan (Carya illinoinensis)

Abstract

WRKY gene family encodes a large transcription factor family that play critical roles in various physiological processes. However, a systematic analysis of the WRKY transcription factor family has not been reported in pecan ( Carya illinoinensis ). In this study, a total of 89 putative pecan WRKY genes ( CiWRKYs ), named CiWRKY1-89 , were identified from the whole genome of pecan. Most of WRKY domain sequences in CiWRKY proteins were “WRKYGQK”, but there were “WRKYGKK” in CiWRKY19, CiWRKY27 and CiWRKY88, and “WKKYGQK” in CiWRKY85. All CiWRKYs were unevenly distributed on 16 chromosomes, the largest number of genes on chromosome 3. Based on phylogenetic analysis, the 89 putative CiWRKYs could be classified into three major groups. The CiWRKY genes shared similar exon-intron distribution, and conserved motifs within the same subgroups. Expression profiles indicated that CiWRKY16 , CiWRKY30 , CiWRKY42 , CiWRKY62 , and CiWRKY69 genes were involved in flower differentiation and development, and majority of CiWRKYs genes were differentially expressed during embryo development. The present study provides reference for further comparative genomics and functional studies of this important class of transcriptional regulators in pecan.