Directional change in leaf dry matter δ 13C during leaf development is widespread in C3 plants

Abstract Background and aims The stable carbon isotope ratio of leaf dry matter (δ 13Cp) is generally a reliable recorder of intrinsic water-use efficiency in C3 plants. Here, we investigated a previously reported pattern of developmental change in leaf δ 13Cp during leaf expansion, whereby emerging leaves are initially 13C-enriched compared to mature leaves on the same plant, with their δ 13Cp decreasing during leaf expansion until they eventually take on the δ 13Cp of other mature leaves. Methods We compiled data to test whether the difference between mature and young leaf δ 13Cp differs between temperate and tropical species, or between deciduous and evergreen species. We also tested whether the developmental change in δ 13Cp is indicative of a concomitant change in intrinsic water-use efficiency. To gain further insight, we made online measurements of 13C discrimination (∆ 13C) in young and mature leaves. Key Results We found that the δ 13Cp difference between mature and young leaves was significantly larger for deciduous than for evergreen species (−2.1 ‰ vs. −1.4 ‰, respectively). Counter to expectation based on the change in δ 13Cp, intrinsic water-use efficiency did not decrease between young and mature leaves; rather, it did the opposite. The ratio of intercellular to ambient CO2 concentrations (ci/ca) was significantly higher in young than in mature leaves (0.86 vs. 0.72, respectively), corresponding to lower intrinsic water-use efficiency. Accordingly, instantaneous ∆ 13C was also higher in young than in mature leaves. Elevated ci/ca and ∆ 13C in young leaves resulted from a combination of low photosynthetic capacity and high day respiration rates. Conclusion The decline in leaf δ 13Cp during leaf expansion appears to reflect the addition of the expanding leaf’s own 13C-depleted photosynthetic carbon to that imported from outside the leaf as the leaf develops. This mixing of carbon sources results in an unusual case of isotopic deception: less negative δ 13Cp in young leaves belies their low intrinsic water-use efficiency.

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Incontinence in aging leaves: deteriorating water relations with leaf age in Agastachys odorata (Proteaceae), a shrub with very long-lived leaves

Functional Plant Biology ◽

10.1071/fp07166 ◽

2007 ◽

Vol 34 (10) ◽

pp. 918 ◽

Cited By ~ 12

Author(s):

Gregory J. Jordan ◽

Timothy J. Brodribb

Keyword(s):

Water Use Efficiency ◽

Water Use ◽

Stomatal Density ◽

Leaf Age ◽

Carbon Assimilation ◽

Leaf Damage ◽

Evergreen Species ◽

Intrinsic Water Use Efficiency ◽

Use Efficiency ◽

Cuticle Thickness

This paper examines physiological characteristics of the leaves of Agastachys odorata R.Br., a wet-climate sclerophyllous shrub with very long-lived leaves. It addresses the hypothesis that cuticles become leakier to water vapour as leaves age. Astomatous cuticular conductance, whole-leaf minimum epidermal conductance, leaf damage and accumulation of epiphylls all increased several-fold with leaf age from first year growth to 10 years of age. Maximum carbon assimilation peaked 1 year after full leaf expansion, then declined. Intrinsic water use efficiency was highest in mid-aged leaves and declined markedly in the oldest leaves. Stomatal density, stomatal size and cuticle thickness did not vary significantly among ages. The older leaves were less effective at controlling water loss, resulting in decreases in water use efficiency. A differential increase in the conductance of the stomatal surface of the leaves relative to astomatous surface suggested that stomatal leakiness was significant in leaves over five years old. Although data for other species is ambiguous, the deterioration in A. odorata appears to be consistent with changes in the oldest leaves of other species. Thus, decreasing ability to use water efficiently appears to be a consequence of accumulated damage and may contribute to the need for leaf senescence in evergreen species with little self shading.

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The Responses of Plant Leaf CO2/H2O Exchange and Water Use Efficiency to Drought: A Meta-Analysis

Sustainability ◽

10.3390/su10020551 ◽

2018 ◽

Vol 10 (2) ◽

pp. 551 ◽

Cited By ~ 16

Author(s):

Jinmeng Zhang ◽

Hong Jiang ◽

Xinzhang Song ◽

Jiaxin Jin ◽

Xiuying Zhang

Keyword(s):

Water Use Efficiency ◽

Water Use ◽

Meta Analysis ◽

Net Photosynthesis ◽

C4 Plants ◽

Deciduous Tree ◽

C3 Plants ◽

Evergreen Species ◽

Plant Leaf ◽

Use Efficiency

Persistent drought severely inhibits plant growth and productivity, which negatively affects terrestrial primary productivity worldwide. Therefore, it is important to investigate the impacts of drought on plant leaf CO2/H2O exchange and water use efficiency. This study assessed the responses of net photosynthesis (Pn), stomatal conductance (Gs), transpiration (Tr), and instantaneous water use efficiency (WUE) to drought based on a worldwide meta-analysis of 112 published studies. The results demonstrated that drought decreased Pn, Tr, and Gs significantly and differently among different moderators. C4 plants had smaller Pn reduction than C3 plants, which gives C4 plants an advantage in Pn. But their WUE decreased under drought conditions, indicating a great flexibility in C4 WUE. Annual herbs sacrificed WUE (−6.2%) to maintain efficient Pn. Perennial herbs took a different strategy in response to drought with an increased WUE (25.1%). Deciduous tree species displayed a greater increase in WUE than conifers and evergreen species. Additionally, Gs had a significant correlation with Pn and Tr, but an insignificant correlation with WUE, which could be because WUE is affected by other factors (e.g., air flow, CO2 concentration, and relative humidity). These findings have significant implications for understanding the worldwide effects of drought on plant leaf CO2/H2O exchange and water use efficiency.

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The Intra-Annual Intrinsic Water Use Efficiency Dynamics Based on an Improved Model

10.21203/rs.3.rs-1060472/v1 ◽

2021 ◽

Author(s):

Xiaojin Bing ◽

Keyan Fang ◽

Xiaoying Gong ◽

Wenzhi Wang ◽

Chenxi Xu ◽

...

Keyword(s):

Water Use Efficiency ◽

Water Use ◽

Pinus Massoniana ◽

C3 Plants ◽

Mountain Area ◽

Southeast China ◽

Intrinsic Water Use Efficiency ◽

Use Efficiency ◽

Improved Model ◽

The Impact

Abstract The carbon isotope fractionation value (Δ) has been widely used to infer the intrinsic water use efficiency (iWUE) of C3 plants. Currently, the most commonly used iWUE method (expressed as iWUE tra ) in tree rings assumes that the mesophyll conductance in plants is infinite. However, many observation-based studies have pointed out that such an assumption leads to overestimating the impact of carbon dioxide (CO 2 ) on intrinsic water use efficiency in plants. In this study, a constant g s /g m ratio (0.79) was introduced for calculating iWUE (expressedas iWUE mes ). We applied this iWUE mes model to our newly developed intra-annual (10 samples per ring) Δ 13 C chronology of Cryptomeria fortunei tree for 1965–2017 at Gu Mountain Area and our annual Δ 13 C chronology of Pinus massoniana tree for 1865–2014 at Niumulin Natural Reserve in southeast China. Using dendrochronology techniques, our analysis revealed that the current iWUE tra model overestimates the iWUE values by approximately 2 times and that the iWUE value of trees inferred from iWUE mes modelling decreased significantly in summer-autumn time, which may indicate that alternative factors play a role in limiting the degree of iWUE improvement under the drought-stressed forest in southeast China.

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Mesophyll conductance to CO2 and Rubisco as targets for improving intrinsic water use efficiency in C3 plants

Plant Cell & Environment ◽

10.1111/pce.12622 ◽

2015 ◽

Vol 39 (5) ◽

pp. 965-982 ◽

Cited By ~ 94

Author(s):

J. Flexas ◽

A. Díaz-Espejo ◽

M. A. Conesa ◽

R. E. Coopman ◽

C. Douthe ◽

...

Keyword(s):

Water Use Efficiency ◽

Water Use ◽

C3 Plants ◽

Mesophyll Conductance ◽

Intrinsic Water Use Efficiency ◽

Use Efficiency

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Genetic improvement of leaf photosynthesis and intrinsic water use efficiency in C3 plants: Why so much little success?

Plant Science ◽

10.1016/j.plantsci.2016.05.002 ◽

2016 ◽

Vol 251 ◽

pp. 155-161 ◽

Cited By ~ 41

Author(s):

J. Flexas

Keyword(s):

Water Use Efficiency ◽

Water Use ◽

Genetic Improvement ◽

C3 Plants ◽

Leaf Photosynthesis ◽

Intrinsic Water Use Efficiency ◽

Use Efficiency

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Rising CO2 drives divergence in water use efficiency of evergreen and deciduous plants

Science Advances ◽

10.1126/sciadv.aax7906 ◽

2019 ◽

Vol 5 (12) ◽

pp. eaax7906 ◽

Cited By ~ 7

Author(s):

Wuu Kuang Soh ◽

Charilaos Yiotis ◽

Michelle Murray ◽

Andrew Parnell ◽

Ian J. Wright ◽

...

Keyword(s):

Water Use Efficiency ◽

Water Use ◽

Boreal Forests ◽

Leaf Mass Per Area ◽

Mean Annual Temperature ◽

Evergreen Species ◽

Intrinsic Water Use Efficiency ◽

Use Efficiency ◽

The Difference ◽

The Impact

Intrinsic water use efficiency (iWUE), defined as the ratio of photosynthesis to stomatal conductance, is a key variable in plant physiology and ecology. Yet, how rising atmospheric CO2 concentration affects iWUE at broad species and ecosystem scales is poorly understood. In a field-based study of 244 woody angiosperm species across eight biomes over the past 25 years of increasing atmospheric CO2 (~45 ppm), we show that iWUE in evergreen species has increased more rapidly than in deciduous species. Specifically, the difference in iWUE gain between evergreen and deciduous taxa diverges along a mean annual temperature gradient from tropical to boreal forests and follows similar observed trends in leaf functional traits such as leaf mass per area. Synthesis of multiple lines of evidence supports our findings. This study provides timely insights into the impact of Anthropocene climate change on forest ecosystems and will aid the development of next-generation trait-based vegetation models.

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