Department of Land, Air & Water Resources, University of California, Davis, CA, 95616, USA,
Photosynth Res. 2014 Feb;119(1-2):119-29. doi: 10.1007/s11120-013-9891-5. Epub 2013 Jul 28.
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 (δ(13)C) 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 δ(13)C. 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 cmax) 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 δ(13)C. 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.
生态学家和生理学家已经记录了拟南芥中广泛的水分利用效率（WUE）变化，以及 WUE 与气候变化的关联。在这里，我们展示了拟南芥不同生活史类群的整株蒸腾效率和碳同位素组成（δ（13）C）之间的相关性。我们还使用整株室来检查 WUE 和 δ（13）C 组成性状的协同变化模式。我们发现，气孔导度（g s）比 A 更能解释 WUE 的变化。总的来说，A 和 g s 之间存在强烈的遗传相关性，这与对这些性状的比值进行选择是一致的。在更详细的水平上，A 的遗传变异是由于羧化最大速率（V cmax）和最大电子传递速率（Jmax）的潜在变异所致。我们还发现叶片解剖结构的强烈影响，其中 WUE 较低的品系具有较高的叶片含水量（LWC）和比叶面积（SLA），这表明叶肉导度（g m）在 WUE 的变化中起作用。我们假设这是由于 g m 的影响，并使用 abi4 突变体来检验这一假设。我们表明，ABI4 突变体比野生型具有更高的 SLA、LWC 和 g m，这与叶片解剖结构的变化导致 g m 和 δ（13）C 的变化一致。这些功能数据也进一步支持了 ABI4 在同时改变 ABA 敏感性、糖信号和 CO2 同化方面的核心、综合作用。总之，我们的结果强调了在功能研究中需要采取更全面的方法，这既是为了更准确地注释基因功能，也是为了了解植物生长和生产力的共同限制。
