A Maize Jasmonate Zim-Domain Protein, ZmJAZ14, Associates with the JA, ABA, and GA Signaling Pathways in Transgenic Arabidopsis

Jasmonate (JA) is an important signaling molecule involved in the regulation of many physiological and stress-related processes in plants. Jasmonate ZIM-domain (JAZ) proteins have been implicated in regulating JA signaling pathways and the cross talk between various phytohormones. Maize is not only an important cereal crop, but also a model plant for monocotyledon studies. Although many JAZ proteins have been characterized in Arabidopsis and rice, few reports have examined the function of JAZ proteins in maize. In this report, we examined the phylogenetic relationship and expression pattern of JAZ family genes in maize. In addition, a tassel and endosperm-specific JAZ gene, ZmJAZ14, was identified using microarray data analysis and real-time RT-PCR, and its expression was induced by polyethylene glycol (PEG), jasmonate (JA), abscisic acid (ABA), and gibberellins (GAs). ZmJAZ14 was shown to be localized in the nucleus and possessed no transcriptional activating activity, suggesting that it functions as a transcriptional regulator. We found that overexpression of ZmJAZ14 in Arabidopsis enhanced plant tolerance to JA and ABA treatment, as well as PEG stress, while it promoted growth under GA stimulus. Moreover, ZmJAZ14 interacted with a subset of transcription factors in Arabidopsis, and the accumulation of several marker genes involved in JA, ABA, and GA signaling pathways were altered in the overexpression lines. These results suggest that ZmJAZ14 may serve as a hub for the cross talk among the JA, ABA, and GA signaling pathways. Our results can be used to further characterize the function of JAZ family proteins in maize, and the gene cloned in this study may serve as a candidate for drought tolerance and growth promotion regulation in maize.