Genome-wide Identification and Expression Pattern Analysis of the HD-Zip Transcription Factor Family in Pineapple (Ananas Comosus)

The Homeodomain leucine zipper (HD-Zip) transcription factor family is one of the most important transcription factor families in the plant kingdom and it plays pivotal roles in plant development, growth as well as response to all kinds of stresses. However, the HD-Zip gene family has not been characterized in pineapple yet. Pineapple is one of the most economically important tropical fruit in the world. Here, we identified a total of 33 HD-Zip genes in pineapple by a genome-wide study. These 33 genes were divided into 4 subgroups and variably located on 14 chromosomes and one scaffold_1724. The gene structure and conserved motifs of these genes relatively share similar characteristics in a subfamily. We found at least two abiotic stress responding cis-elements in the promoter region of AcoHDzip genes, the light-responsive element is the most abundant cis-element that can be found in all the genes. Besides, transcriptome analysis showed the expression profile of 33 genes in different developmental stages. We identified the nine genes with higher expression in gynoecium and two genes with highly expressed in ovules and flowers respectively. Our studies will provide valuable information about the HD-Zip transcription factor family in pineapple, which would be useful for further functional studies in plant growth, plant development, and stress response.