Article Figures & Data
Figures
- Figure 1.
Overview of Gibberellin Metabolism in Higher Plants.
Bioactive GAs (circled) are biosynthesized from GA12 by oxidation of C-20 by GA20ox to GA20 and GA9 followed by 3β oxidation by GA3ox. Bioactive GA1 and GA4 are inactivated by GA2 oxidation to GA34 and GA8 by GA2ox.
- Figure 2.
LFY Expression and GA and Sugar Quantifications during Flower Initiation.
(A) Real-time RT-PCR analysis of LFY expression in excised shoot apices during growth in short days. Estimated time of flower induction is marked by shaded area. Values are expressed relative to 18S rRNA. Inset: semiquantitative RT-PCR analysis of AP1 and AP3 expression in excised shoot apices during growth in short days. The 18S rRNA was amplified as an internal control. AP1 can be detected from day 42 and AP3 from day 49. Numbers indicate days after sowing.
(B) Gas chromatography–mass spectrometry (GC-MS) quantifications of the levels of GA1, GA4, and GA5 in excised shoot apices during growth in short days. Microdissected shoot apices from 20 to 30 plants were pooled for each time point. Values are expressed as means ± se of the mean (n = 3).
(C) GC-MS quantifications of the levels of soluble sugars in excised shoot apices during growth in short days. Microdissected shoot apices from 20 to 30 plants were pooled for each time point. Values are expressed as means ± se of the mean (n = 3). Shaded area indicates estimated time for flower initiation.
- Figure 3.
Flowering Time of Short-Day-Grown Plants after Treatment with Various GAs to the Shoot Apex.
Treatment was done from day 28, twice per week, until day 56. Time to flowering was determined as the total number of leaves in the primary shoot. Values are shown as the means ± 2 × se of the mean (n = 9). Asterisks indicate values that are significantly different from the control (Student's t test, P < 0.05)
- Figure 4.
Dose–Response Curves for the Activation of LFY:GUS Expression by Different GAs.
(A) Dose–response curves for the activation of LFY by different GAs in short-day-grown plants. Twenty-four-day-old plants were treated three times, at 2-d intervals, by application of 20 μL of different concentrations of various GAs to the shoot apical part of the plant. Plants were then assayed for GUS activity. Values are shown as the means ± 2 × se of the mean (n = 24).
(B) Three-day-old seedlings grown in half-strength Murashige and Skoog medium supplemented with 0.5% sucrose were treated with different concentrations of GA1, GA3, GA4, GA5, GA6, and GA8 for 3 d and then assayed for GUS activity. Values are shown as means ± 2 × se of the mean (n = 24). MUG, 4-methylumbelliferyl β-d-glucuronide.
- Figure 5.
Expression of Genes Involved in GA Metabolism in Shoot Apices.
RT-PCR (A) and real-time RT-PCR ([B] and [C]) analyses of gene expression in excised shoot apices during growth in short days. Values are expressed relative to 18S rRNA.
(A) Expression of GA20OX1, GA20OX2, and GA20OX3. n.d., not determined.
(B) Expression of GA3OX1 and GA3OX2.
(C) Expression of the GA2OX genes. Values are expressed as means ± se of the mean (n = 3).
Tables
Sample Ratio (m/z 420→392)/(m/z 418→390) Nonlabeled GA4 standard 0.13 Shoot apices in 2H2-GA4 leaf-fed plants 0.21 2H2-GA4 transport was detected by measuring endogenous and labeled GA4 in apex samples and GA4 standards with GC-MS in selected reaction monitoring mode and comparing the ratio of endogenous and labeled GA4 in the sample and GA4 standard. m/z, mass-to-charge ratio.
Supplemental Data
Files in this Data Supplement:
- Supplemental Table 1 - Sequence of Forward and Reverse Primers Used for Quantification of mRNA by RT-PCR.
