The phytochrome-interacting family of transcription factors in maize (Zea mays L.): identification, evolution, and expression analysis

The phytochrome-interacting factor (PIF) subfamily of transcription factors is among the most important families of plant transcriptional regulators. PIFs regulate multiple biological processes, especially the photomorphogenic development. However, studies on PIF are mostly concentrated in Arabidopsis, little information on PIFs in maize (Zea mays L.) is currently available. The release of assembled genome sequences of maize enables the genome-wide investigation of maize PIF proteins. In this study, six PIF genes in maize were identified and named ZmPIF1-6. Among them, ZmPIF1 and ZmPIF3 were previously cloned in our laboratory. According to the structural features of their proteins, maize PIF genes (ZmPIFs) were classified into two main groups. Group I have an active phytochrome B (APB) domain and interacts with ZmphyB1. Group II has APA and APB domains and interacts with ZmphyA1 and ZmphyB1. The global expression patterns of ZmPIF genes in various tissues, as well as response of ZmPIF genes to diurnal rhythm, environmental stresses, and plant hormones were analyzed. The expression patterns of the ZmPIF genes suggested that ZmPIF1 and ZmPIF3 play an important role in the diurnal rhythm, while ZmPIF4 and ZmPIF6 are possibly the genes that respond to stimulation during plant growth and development. Meanwhile, the functions of ZmPIF2 and ZmPIF5 requires further investigation. These results can facilitate the exploration of the role of maize PIF-mediated plant signaling pathways and contribute to the development of molecular breeding for maize.