Identification and Characterization of ZF-HD Genes in Response to Abscisic Acid and Abiotic Stresses in Maize

The zinc finger homeodomain (ZF-HD) genes belong to the homeobox gene family, playing critical roles in flower development and stress response. Despite their importance, however, to date there has been no genome-wide identification and characterization of the ZF-HD genes that are probably involved in stress responses in maize. In this study, 24 ZF-HD genes were identified, and their chromosomal locations, protein properties, duplication patterns, structures, conserved motifs and expression patterns were investigated. The results revealed that the ZF-HD genes are unevenly distributed on nine chromosomes and that most of these genes lack introns. Six and two ZF-HD genes have undergone segmental and tandem duplication, respectively, during genome expansion. These 24 ZF-HD transcription factors were classified into six major groups on the basis of protein molecular evolutionary relationship. The expression profiles of these genes in different tissues were evaluated, resulting in producing two distinct clusters. ZF-HD genes are preferentially expressed in reproductive tissues. Furthermore, expression profiles of the 24 ZF-HD genes in response to different kinds of stresses revealed that ten genes were simultaneously up-regulated under ABA, salt and PEG treatments; meanwhile four genes were simultaneously down-regulated. These findings will pave the way for deciphering the function and mechanism of ZF-HD genes on how to implicate in abiotic stress.