title: Genome-wide identification,  classification, and analysis of two-component signal system genes in maize.
abstract: Cytokinins  play many vital roles in plant development and physiology. In plants, cytokinin  signals are sensed and transduced by the two-component signal system. This  signaling cascade is typically composed of three proteins: a sensory histidine  kinase, a histidine phosphotransfer protein, and a response regulator. Through  a comprehensive genome-wide analysis of the maize (Zea mays) genome, 48  genes were identified, including 11 ZmHKs, 9 ZmHPs, and 28 ZmRRs  (21 A-type ZmRRs and 7 B-type ZmRRs). Using maize genome sequence  databases, we analyzed conserved protein motifs and established phylogenetic  relationships based on gene structure, homology, and chromosomal location. The  duplication of these two-component system genes in the maize genome  corresponded to the clusters of these genes in the phylogenetic trees. Sequence  analysis of the duplicate genes demonstrated that one gene may be in gene  duplication, and that there was significant variation in the evolutionary  history of the different gene families. We assessed the expression levels of  all ZmRRs in the leaves and roots by reverse transcription PCR; they  were all found to be active. Our results provide a foundation for functional  and evolutionary studies on maize two-component signal system proteins.
authors.affiliation: Anhui Province Key Laboratory of Crop Biology, School of Life Science, Anhui Agricultural University, Hefei, China.
authors.forename: Z X
authors.initials: ZX
authors.lastname: Chu
authors.forename: Q
authors.initials: Q
authors.lastname: Ma
authors.forename: Y X
authors.initials: YX
authors.lastname: Lin
authors.forename: X L
authors.initials: XL
authors.lastname: Tang
authors.forename: Y Q
authors.initials: YQ
authors.lastname: Zhou
authors.forename: S W
authors.initials: SW
authors.lastname: Zhu
authors.forename: J
authors.initials: J
authors.lastname: Fan
authors.forename: B J
authors.initials: BJ
authors.lastname: Cheng
mesh_terms: D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000235:genetics; D017124:Conserved Sequence / Q000235:genetics; D003583:Cytokinins / Q000235:genetics; D018076:DNA, Complementary / Q000235:genetics; D020440:Gene Duplication / Q000235:genetics; D018506:Gene Expression Regulation, Plant; D017343:Genes, Plant / Q000235:genetics*; D008969:Molecular Sequence Data; D012275:Oryza / Q000235:genetics; D010802:Phylogeny; D018515:Plant Leaves / Q000235:genetics; D010940:Plant Proteins / Q000737:chemistry / Q000235:genetics; D018517:Plant Roots / Q000235:genetics; D018749:RNA, Plant / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism; D016415:Sequence Alignment; D017422:Sequence Analysis, DNA; D015398:Signal Transduction / Q000235:genetics*; D003313:Zea mays / Q000235:genetics*
chemical_list: D003583:Cytokinins; D018076:DNA, Complementary; D010940:Plant Proteins; D018749:RNA, Plant