Genes responsive to elevated CO2 concentrations in triploid white poplar and integrated gene network analysis.
BACKGROUND
The atmospheric CO2 concentration increases every year. While the effects of elevated CO2 on plant growth, physiology and metabolism have been studied, there is now a pressing need to understand the molecular mechanisms of how plants will respond to future increases in CO2 concentration using genomic techniques.


RESULTS
Gene expression in triploid white poplar ((Populus tomentosa ×P. bolleana) ×P. tomentosa) leaves was investigated using the Affymetrix poplar genome gene chip, after three months of growth in controlled environment chambers under three CO2 concentrations. Our physiological findings showed the growth, assessed as stem diameter, was significantly increased, and the net photosynthetic rate was decreased in elevated CO2 concentrations. The concentrations of four major endogenous hormones appeared to actively promote plant development. Leaf tissues under elevated CO2 concentrations had 5,127 genes with different expression patterns in comparison to leaves under the ambient CO2 concentration. Among these, 8 genes were finally selected for further investigation by using randomized variance model corrective ANOVA analysis, dynamic gene expression profiling, gene network construction, and quantitative real-time PCR validation. Among the 8 genes in the network, aldehyde dehydrogenase and pyruvate kinase were situated in the core and had interconnections with other genes.


CONCLUSIONS
Under elevated CO2 concentrations, 8 significantly changed key genes involved in metabolism and responding to stimulus of external environment were identified. These genes play crucial roles in the signal transduction network and show strong correlations with elevated CO2 exposure. This study provides several target genes, further investigation of which could provide an initial step for better understanding the molecular mechanisms of plant acclimation and evolution in future rising CO2 concentrations.
State Key Laboratory of Tree Genetics and Breeding, Research Institute of Forestry, Chinese Academy of Forestry, Beijing, China; Key Laboratory of Tree Breeding and Cultivation of the State Forestry Administration, Research Institute of Forestry, Chinese Academy of Forestry, Beijing, China.
Juanjuan
J
Liu
State Key Laboratory of Tree Genetics and Breeding, Research Institute of Forestry, Chinese Academy of Forestry, Beijing, China; Key Laboratory of Tree Breeding and Cultivation of the State Forestry Administration, Research Institute of Forestry, Chinese Academy of Forestry, Beijing, China.
Jianguo
J
Zhang
State Key Laboratory of Tree Genetics and Breeding, Research Institute of Forestry, Chinese Academy of Forestry, Beijing, China; Key Laboratory of Tree Breeding and Cultivation of the State Forestry Administration, Research Institute of Forestry, Chinese Academy of Forestry, Beijing, China.
Caiyun
C
He
State Key Laboratory of Tree Genetics and Breeding, Research Institute of Forestry, Chinese Academy of Forestry, Beijing, China; Key Laboratory of Tree Breeding and Cultivation of the State Forestry Administration, Research Institute of Forestry, Chinese Academy of Forestry, Beijing, China.
Aiguo
A
Duan
D000444:Aldehyde Dehydrogenase / Q000235:genetics; D002245:Carbon Dioxide / Q000737:chemistry*; D019295:Computational Biology; D005740:Gases; D005786:Gene Expression Regulation; D053263:Gene Regulatory Networks; D023281:Genomics; D020411:Oligonucleotide Array Sequence Analysis; D010788:Photosynthesis; D018515:Plant Leaves / Q000235:genetics / Q000378:metabolism; D011123:Polyploidy; D032107:Populus / Q000235:genetics* / Q000378:metabolism*; D011770:Pyruvate Kinase / Q000235:genetics; D060888:Real-Time Polymerase Chain Reaction; D015398:Signal Transduction; D059467:Transcriptome; D014197:Trees / Q000235:genetics / Q000378:metabolism
D005740:Gases; D002245:Carbon Dioxide; D000444:Aldehyde Dehydrogenase; D011770:Pyruvate Kinase