We also show strong covariation between LWC and δ13C, where spring annuals tend to have higher LWC and lower intrinsic WUE. We hypothesize that this is due to an effect through g m, and test this hypothesis using the abi4 mutant. The abi4 mutant shows increased SLA and reduced g m compared to the wildtype, consistent with the pattern of covariance

found in the natural accessions. Previous separate studies in Arabidopsis have addressed variation in δ13C, plant–water relations, leaf anatomy, and photosynthetic capacity and limitations, including g m. Here, we use a whole canopy approach to examine variation and covariation GSK2126458 ic50 in all of these components. As predicted by optimality, these traits are not independent, but instead covary as would be expected if selection and photosynthetic acclimation favors states of colimitation. In addition, we show that perturbation

of a single transcription factor leads to this trait covariance. This emphasizes the need for whole plant approaches and high dimensional phenotyping to accurately annotate the gene function. Acknowledgments We thank P Rispin for help in completing the TE experiment. This research is supported by NSF grants DEB-1022196 and DEB-0618302 to JKM, DEB-0618347 to TEJ, IOS-0719118 to DTH, DEB-0618294 to JHR, USDA NIFA 2007-35100-18379 to TEJ, and NIH-NCRR P20RR18754. Support from the California and Colorado Agricultural Experiment Stations is also acknowledged. Open AccessThis article is distributed under the terms of the Creative Commons Attribution License which permits any use, distribution, and reproduction in any medium, Akt inhibitor provided the original author(s) and the source are credited. OSI-906 in vitro References Araus JL, Slafer GA, Reynolds MP, Royo C (2002) Plant breeding and drought in C3 cereals: what should we breed for? Ann Bot 89:925–940PubMedCrossRef Barbour MM, McDowell NG, Tcherkez G, Bickford CP, Hanson DT (2007) A new measurement technique reveals rapid post-illumination changes in the carbon isotope composition of leaf-respired CO2. Plant Cell Environ 30:469–482PubMedCrossRef Barbour MM, Warren CR, Farquhar GD, Forrester G,

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