HD-zip III homeobox genes that include a novel member, ZeHB-13 (Zinnia)/ATHB-15 (Arabidopsis), are involved in procambium and xylem cell differentiation.
HD-Zip III homeobox genes are known to be essential transcriptional factors for vascular development. To further understand the relation of HD-Zip III genes in vascular differentiation, we isolated a new member of the HD-Zip III genes, ZeHB-13, as a Zinnia homolog of ATHB-15, and then characterized the expression profile using a Zinnia xylogenic cell culture and Zinnia plants. We compared the accumulation pattern of transcripts for ZeHB-13 and other HD-Zip III genes and suggested that the expression of ZeHB-13 was restricted to the procambium and was not severely suppressed by brassinazole, an inhibitor of brassinosteroid biosynthesis, unlike other HD-Zip III genes. We also characterized its Arabidopsis counterpart, ATHB-15. A histochemical promoter analysis using ATHB-15::GUS transgenic Arabidopsis plants indicated that ATHB-15 was active specifically in the procambium. These results strongly suggest that ZeHB-13/ATHB-15 is a pivotal transcriptional regulator responsible for early vascular development. Based on these results, we will discuss the regulation of xylem development in light of the functions of HD-Zip III members and brassinosteroids.
Ohashi-Ito
Kyoko
K
Department of Biological Sciences, Graduate School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, Japan. kyoko@biol.s.u-tokyo.ac.jp
Fukuda
Hiroo
H
D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism; D029681:Arabidopsis Proteins / Q000235:genetics* / Q000378:metabolism; D019659:Asteraceae / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism; D001483:Base Sequence; D002454:Cell Differentiation / Q000235:genetics* / Q000502:physiology; D002478:Cells, Cultured; D003001:Cloning, Molecular; D018076:DNA, Complementary / Q000737:chemistry / Q000235:genetics; D018507:Gene Expression Regulation, Developmental; D018506:Gene Expression Regulation, Plant; D018398:Homeodomain Proteins / Q000235:genetics* / Q000378:metabolism; D016350:Leucine Zippers / Q000235:genetics / Q000502:physiology; D008969:Molecular Sequence Data; D010802:Phylogeny; D010940:Plant Proteins / Q000235:genetics* / Q000378:metabolism; D018514:Plant Structures / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism; D030821:Plants, Genetically Modified; D017422:Sequence Analysis, DNA; D017386:Sequence Homology, Amino Acid; D012689:Sequence Homology, Nucleic Acid; D014157:Transcription Factors / Q000235:genetics* / Q000378:metabolism; D014230:Triazoles / Q000494:pharmacology
D029681:Arabidopsis Proteins; D018076:DNA, Complementary; C482920:HB-15 protein, Arabidopsis; D018398:Homeodomain Proteins; D010940:Plant Proteins; D014157:Transcription Factors; D014230:Triazoles; C412342:brassinazole