4 research outputs found
Field-grown <i>Pro<sub>35S</sub></i>:<i>CO1</i>, <i>Pro<sub>35S</sub></i>:<i>CO2</i>, and control trees were observed for the onset of reproduction for five years, evaluated for the number of reproductive buds or catkins at age 5, and measured for height, diameter, and shoot growth at age 5.
<p>Differing letters to the right of the mean (superscript) within a row represent a statistical difference (<i>P</i>≤0.05) between the average control and average transformant. Height was measured in meter (m), whereas diameter and shoot length were measured in centimeter (cm).</p
<i>In situ</i> expression analysis of <i>CO1</i> and <i>CO2</i> in leaf, reproductive bud, and shoot apex collected during the growing season from mature <i>P. deltoides</i>.
<p>Panels in the first two columns were results from the bright-field image of <i>in situ</i> hybridization and colorimetric detection of <i>CO1</i> or <i>CO2</i> transcripts. The antisense probe generated positive signals (dark blue) if present, while the sense probe served as negative control. The third column (schematic drawing) illustrates leaf cross-sections and longitudinal reproductive bud and shoot apex sections where <i>CO1</i> and <i>CO2</i> transcripts (pink color) were located, based on visual observations, as well as captured images. Scale bar, 100 µm.</p
Transcripts downstream of <i>CO1</i> and <i>CO2</i> and their year-round transcript levels were identified in mature <i>P. deltoides</i> via microarray.
<p>Log<sub>2</sub> fold-change of each time point relative to the baseline time point (September or Sep) was calculated. Clusters to the left of the heatmaps represent modules and the columns to right of the heatmaps represent the up- (red) and down-regulation (blue) of downstream genes. Months relative to September are above the heatmaps. The pie charts to the right of each heatmap show the functional categorization of GO Biological Process terms. N = number of genes. The Venn diagram shows the number of genes that were common to both <i>CO1</i> and <i>CO2</i> (<i>CO1</i>/<i>CO2</i>) datasets, and the pie chart below the diagram shows the GO categorization of <i>CO1</i>/<i>CO2</i> transcripts. Up (↑) and down (↓) arrows represent partitioning of overall percentage in each pie. “**” denotes the GO term is significantly (<i>P</i>≤0.001, except “development” for genes downstream of <i>CO1 P</i>≤0.006) over-represented in the microarray data when a hypergeometric test was conducted.</p
Ectopic expression of <i>CO1</i> and <i>CO2</i> individually (<i>Pro<sub>35S</sub></i>:<i>CO1</i> or <i>Pro<sub>35S</sub></i>:<i>CO2</i>) or together (<i>Pro<sub>35S</sub></i>:<i>CO1/CO2</i>) in poplar (<i>P. tremula</i> Ă— <i>P alba</i>).
<p>(A) When compared with controls at age 5, <i>Pro<sub>35S</sub></i>:<i>CO1</i> or <i>Pro<sub>35S</sub></i>:<i>CO2</i> trees did not differ in reproductive onset, spring reproductive and vegetative bud break, and fall bud set. <i>Pro<sub>35S</sub></i>:<i>FT2</i> trees showed year-round active growth. Red arrows denote the emerging inflorescence in the spring, whereas black arrows point the dormant terminal vegetative bud in the fall. Unlike wild-type and vector controls, <i>Pro<sub>35S</sub></i>:<i>CO1</i> or <i>Pro<sub>35S</sub></i>:<i>CO2</i> trees (1, 2, and 3) significantly overproduced <i>CO1</i> or <i>CO2</i> transcripts when analyzed via qRT-PCR in leaves sampled in April. While the expression of <i>FT1</i> was undetectable, that of <i>FT2</i> fluctuated with no clear trend in controls and <i>CO1</i>- or <i>CO2</i>-overexpressing trees. Letters above the bars showing the abundance of <i>CO1</i> or <i>CO2</i> transcripts indicate statistically significant (<i>P</i>≤0.001) differences. Error bars indicate SD about the mean. (B) When <i>Pro<sub>35S</sub></i>:<i>CO1</i> and <i>Pro<sub>35S</sub></i>:<i>CO2</i> were co-expressed in the same trees, no difference between the transformants and controls was observed in spring bud break and fall bud set in two years. However, <i>Pro<sub>35S</sub></i>:<i>FT2</i> trees showed a non-dormant phenotype. Black arrows indicate the terminal vegetative bud, whereas purple arrows point to the axillary vegetative bud. The axillary vegetative buds were opening and preformed leaves were emerging from the control and co-expressing transgenic trees on March 23. Unlike wild-type and vector-control plants, co-expressing transgenic trees (1, 2, 3, and 4) significantly overproduced <i>CO1</i> and <i>CO2</i> transcripts in leaves sampled in April. While the expression of <i>FT1</i> was undetectable, that of <i>FT2</i> fluctuated with no clear trend in controls and <i>CO1</i>/<i>CO2</i> overexpressing trees. Letters above the bars showing the abundance of <i>CO1</i> or <i>CO2</i> transcripts indicate statistically significant (<i>P</i>≤0.001) differences. Error bars indicate SD about the mean.</p