Huang, Li-Chun , Huang, Hao-Jen , Chow, Teh-Yuan .
DNA Methylation and Rearrangements Observed in Mitochondria and Nuclei with Developmental Phase Reversal of Sequoia sempervirens In Vitro.
Maturation of trees is frequently accompanied by a decline in vigor and diminishment of organogenetic competence. Rejuvenation, or phase reversal, can be achieved by repeated grafting of shoot apices from matured adult trees onto juvenile rootstocks in vitro or in vivo. Our studies demonstrated that significant phase reversal of the coastal redwood (Sequoia sempervirens), as evidenced by restoration of plant vigor and 100% rooting of shoot cuttings, can result after four successively repeated grafts in vitro. Juvenile leaf morphology and phyllotaxy were also restored. Studies of the molecular mechanism disclosed a mtDNA polymorphism between juvenile and adult shoots. Juvenile and rejuvenated tissues contained 6 small (3.2 – 4.5 kb) circular mtDNA molecules, whereas the adult contained only 2. DNA sequencing disclosed 38 to 56% similarity among these 6 unrestricted small molecules. HPLC analyses revealed a higher nucDNA methylation in the adult (8.6% methylated cytosine vs. 7.3% of juvenile or 7.0% of rejuvenated), but lower mtDNA methylation in the adult (6.6% vs. 7.8% of juvenile and 8.2% of rejuvenated). Methylation specific AFLP analysis (restricted by Eco RI/ Hpa II) revealed nucDNA rearrangement as evident among PCR amplified restriction fragments with designed primers. Cloning and sequencing of selected fragments of each of juvenile, adult and rejuvenated methylated nucDNA generated juvenile- and adult-specific fragments.
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1 - Institute of Plant and Microbial Biology, Academia Sinica, Nankang, Taipei, Taiwan, 11529, Republic of China
2 - Department of Life Sciences, National Cheng Kung University, No.1, Ta-Hsueh Road, Tainan, Taiwan, 70101, Republic of China
mtDNA and nucDNA rearrangements.
Presentation Type: Oral Paper:Papers for Sections
Location: Stevens 1/Hilton
Date: Wednesday, July 11th, 2007
Time: 2:45 PM