Effect of ANL2 homolog (A2H) on flowering in Arabidopsis.

• Project/Area Number: 16570171
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Single-year Grants
• Section: 一般
• Research Field: Developmental biology
• Research Institution: Shinshu University
• Principal Investigator: KUBO Hiroyoshi Shinshu University, Faculty of Science, Associate Professor, 理学部, 助教授 (60205127)
• Project Period (FY): 2004 – 2005
• Project Status: Completed (Fiscal Year 2005)
• Budget Amount: ¥2,800,000 (Direct Cost: ¥2,800,000); Fiscal Year 2005: ¥900,000 (Direct Cost: ¥900,000); Fiscal Year 2004: ¥1,900,000 (Direct Cost: ¥1,900,000)
• Keywords: ANL2 homolog / flowering / シロイヌナズナ / 花芽誘導

Research Abstract

We isolated a a2h mutant from a tagging line and examined the phenotype of the a2h mutant. The a2h mutant accumulated reduced amount of anthocyanin but the celluar organization of the primary root is normal. The a2h mutant showed a slight early flowering phenotype. Expression of A2H was not affected in several late-flowering mutants and tfl1. Overexpression of whole region of A2H, HD-ZIP domain, START domain of A2H caused slight early flowering. The result for overexpression of A2H was unexpected and further examination is required. Another gene located on upper part of chromosome5 was suggested to be involved in early flowering phenotype of a2h mutant.
Next, we examined the promoter activity of A2H and ANL2 using uidA as a reporter. The 2kb promoter region of A2H and ANL2 did not direct proper GUS expression. When a posterior region of these genes was added downstream of the nos terminator of uidA, proper GUS expression was observed. GUS expression was observed in leaf, root and stamen in plants harboring A2H::GUS construct. In plants harboring ANL2::GUS construct, GUS expression was observed in the shoot apex and root tip where ANL2 expression is expected from the phenotype of anl2 mutant. Strong GUS expression was observed in the shoot apex, young leaves, root tips, anthers and ovules. In young tissues of shoot, GUS expressed in epidermal and subepidermal tissues. In situ hybridization revealed that ANL2 mRNA was confined to epidermis and subepidermis of shoot and flower meristems. In rosette leaves, subepidermal tissues showed much strong GUS expression, while epidermal cells including guard cells and trichome showed weak GUS expression. In the primary root, GUS was expressed in cells in the epidermis and lateral root cap that are derived from the initial cells in the root epidermis, indicating that ANL2 functions in the epidermis of root and determines its nature. A conserved motif in the HD-GL2 group (HD-GL2 motif) was essential for GUS expression, indicating that it is necessary for transcriptional regulation of ANL2.