Investigation of the JASMONATE ZIM-DOMAIN Gene Family Reveals the Canonical JA-Signaling Pathway in Pineapple

SIMPLE SUMMARY: JASMONATE ZIM-DOMAIN (JAZ) proteins are key components of the jasmonate (JA) signaling pathway in response to biotic and abiotic stresses in plants. Information about the JAZ gene family in pineapple (AcJAZ) is limited. In this study, 14 AcJAZ genes were identified in the pineapple genome. A complete overview of AcJAZ genes is presented, including the chromosome locations, phylogenetic relationships, gene structures, conserved motifs and cis-regulatory elements, and expression patterns at different developmental stages and under various stress conditions, and their possible involvement in diverse functions is suggested. Furthermore, the BiFC analysis revealed direct binary interactions between AcJAZs and crucial JA-signaling regulators in vivo. These results suggest that AcJAZs and other vital players function in the JA-signaling pathway in response to abiotic stresses in pineapple. ABSTRACT: JASMONATE ZIM-DOMAIN (JAZ) proteins are negative regulators of the jasmonate (JA)-signaling pathway and play pivotal roles in plant resistance to biotic and abiotic stresses. Genome-wide identification of JAZ genes has been performed in many plant species. However, systematic information about pineapple (Ananas comosus L. Merr.) JAZ genes (AcJAZs) is still not available. In this study, we identified 14 AcJAZ genes and classified them into five groups along with the Arabidopsis and rice orthologs. The AcJAZ genes have 3–10 exons, and the putative AcJAZ proteins have between two and eight conserved regions, including the TIFY motif and Jas domain. The cis-acting element analysis revealed that the putative promoter regions of AcJAZs contain between three and eight abiotic stress-responsive cis-acting elements. The gene-expression analysis suggested that AcJAZs were expressed differentially during plant development and subjected to regulation by the cold, heat, salt, and osmotic stresses as well as by phytohormones. Moreover, the BiFC analysis of protein interactions among the central JA-signaling regulators showed that AcJAZ4, AcMYC2, AcNINJA, and AcJAM1 could interact with AcJAZ5 and AcJAZ13 in vivo, indicating a canonical JA-signaling pathway in pineapple. These results increase our understanding of the functions of AcJAZs and the responses of the core players in the JA-signaling pathway to abiotic stresses.