Journal
PHOTOSYNTHESIS RESEARCH
Volume 119, Issue 1-2, Pages 119-129Publisher
SPRINGER
DOI: 10.1007/s11120-013-9891-5
Keywords
ABI4; Carbon isotope composition; Mesophyll conductance; Photosynthetic capacity; Stomatal conductance
Categories
Funding
- NSF [DEB-1022196, DEB-0618302, DEB-0618347, IOS-0719118, DEB-0618294]
- USDA NIFA [2007-35100-18379]
- NIH-NCRR [P20RR18754]
- California Agricultural Experiment Station
- Colorado Agricultural Experiment Station
- Division Of Environmental Biology
- Direct For Biological Sciences [1022196] Funding Source: National Science Foundation
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Ecologists and physiologists have documented extensive variation in water use efficiency (WUE) in Arabidopsis thaliana, as well as association of WUE with climatic variation. Here, we demonstrate correlations of whole-plant transpiration efficiency and carbon isotope composition (delta C-13) among life history classes of A. thaliana. We also use a whole-plant cuvette to examine patterns of co-variation in component traits of WUE and delta C-13. We find that stomatal conductance (g (s)) explains more variation in WUE than does A. Overall, there was a strong genetic correlation between A and g (s), consistent with selection acting on the ratio of these traits. At a more detailed level, genetic variation in A was due to underlying variation in both maximal rate of carboxylation (V (c)max) and maximum electron transport rate (Jmax). We also found strong effects of leaf anatomy, where lines with lower WUE had higher leaf water content (LWC) and specific leaf area (SLA), suggesting a role for mesophyll conductance (g (m)) in variation of WUE. We hypothesize that this is due to an effect through g (m), and test this hypothesis using the abi4 mutant. We show that mutants of ABI4 have higher SLA, LWC, and g (m) than wild-type, consistent with variation in leaf anatomy causing variation in g (m) and delta C-13. These functional data also add further support to the central, integrative role of ABI4 in simultaneously altering ABA sensitivity, sugar signaling, and CO2 assimilation. Together our results highlight the need for a more holistic approach in functional studies, both for more accurate annotation of gene function and to understand co-limitations to plant growth and productivity.
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