Physiological advantages of C4 grasses in the field: a comparative experiment demonstrating the importance of drought.
Physiological advantages of C4 grasses in the field: a comparative experiment demonstrating the importance of drought.
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DOI：
10.1111/gcb.12498
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发表时间：
2014-06
影响因子：
11.6
通讯作者：
Osborne CP
中科院分区：
文献类型：
--
作者：
Taylor SH;Ripley BS;Martin T;De-Wet LA;Woodward FI;Osborne CP
全球气候变化预计将改变区域降雨模式，影响依赖于水供应的物种分布。比较研究表明，与C3近缘植物相比，C4牧草生长在更干燥的生境中，但C3和C4光合作用都对干旱敏感。然而，C4植物在干旱环境中可能会显示出水力性能的优势。我们研究了水分供应的季节变化对叶片生理的影响，使用南非东开普省的一个普通园艺试验比较了来自C4和C3姐妹系的12种当地发生的草种。C4草的光合作用在每个月都高于C3草，但在最潮湿的月份差异不显著。令人惊讶的是，C3的气孔导度通常低于C4草，C3种的月平均气孔导度峰值与C4叶相似。在缺水雨养小区中，C4叶片的光合作用比C3植株的光合作用高2~7.4mmolm−2，S−1高1，气孔导度增加近一倍，蒸腾作用提高60%。尽管C4平均瞬时水分利用效率(2.4-8.1mmol.mol−1)高于C3平均(0.7mmol.moL−1)，但差异并不像我们预期的那么大，只有在干旱形成时才有统计意义。干旱期间，C3种植物的光合作用下降早于C4种，与气孔导度和蒸腾作用的下降相一致。C4植物光合作用的最终下降与中午叶水势的下降有关。然而，在干旱的同一阶段，C3物种表现出水动力梯度的显著下降，这表明水力破坏。因此，我们的结果表明，干旱期间的气孔和水力行为增强了C4和C3物种之间的光合作用差异。我们认为，这些干旱反应对于理解C4光合作用在田间条件下的优势是重要的。
Global climate change is expected to shift regional rainfall patterns, influencing species distributions where they depend on water availability. Comparative studies have demonstrated that C4 grasses inhabit drier habitats than C3 relatives, but that both C3 and C4 photosynthesis are susceptible to drought. However, C4 plants may show advantages in hydraulic performance in dry environments. We investigated the effects of seasonal variation in water availability on leaf physiology, using a common garden experiment in the Eastern Cape of South Africa to compare 12 locally occurring grass species from C4 and C3 sister lineages. Photosynthesis was always higher in the C4 than C3 grasses across every month, but the difference was not statistically significant during the wettest months. Surprisingly, stomatal conductance was typically lower in the C3 than C4 grasses, with the peak monthly average for C3 species being similar to that of C4 leaves. In water-limited, rain-fed plots, the photosynthesis of C4 leaves was between 2.0 and 7.4 μmol m−2 s−1 higher, stomatal conductance almost double, and transpiration 60% higher than for C3 plants. Although C4 average instantaneous water-use efficiencies were higher (2.4–8.1 mmol mol−1) than C3 averages (0.7–6.8 mmol mol−1), differences were not as great as we expected and were statistically significant only as drought became established. Photosynthesis declined earlier during drought among C3 than C4 species, coincident with decreases in stomatal conductance and transpiration. Eventual decreases in photosynthesis among C4 plants were linked with declining midday leaf water potentials. However, during the same phase of drought, C3 species showed significant decreases in hydrodynamic gradients that suggested hydraulic failure. Thus, our results indicate that stomatal and hydraulic behaviour during drought enhances the differences in photosynthesis between C4 and C3 species. We suggest that these drought responses are important for understanding the advantages of C4 photosynthesis under field conditions.
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影响因子：
4.8
作者：
Clark, JS
通讯作者：
Clark, JS
DOI：
10.1073/pnas.0909672107
发表时间：
2010-02-09
影响因子：
11.1
作者：
Edwards, Erika J.;Smith, Stephen A.
通讯作者：
Smith, Stephen A.
影响因子：
9.4
作者：
Ghannoum, O;Conroy, JP;Lawlor, DW
通讯作者：
Lawlor, DW
影响因子：
8.8
作者：
Edwards, Erika J.;Still, Christopher J.
通讯作者：
Still, Christopher J.
影响因子：
3.7
作者：
ELSHARKAWY, MA;COCK, JH;HERNANDEZ, AD
通讯作者：
HERNANDEZ, AD