Variability in hydraulic architecture and gas exchange of common bean (Phaseolus vulgaris) cultivars under well-watered conditions: interactions with leaf size

1999 ◽  
Vol 26 (2) ◽  
pp. 115 ◽  
Author(s):  
Maurizio Mencuccini ◽  
Jonathan Comstock
Keyword(s):  
Gas Exchange ◽  
Exchange Rates ◽  
Common Bean ◽  
Water Loss ◽  
Leaf Size ◽  
Hydraulic Conductance ◽  
Hydraulic Architecture ◽  
Greenhouse Study ◽  
Whole Plant ◽  
Leaf Level

In a greenhouse study, 12 common bean cultivars from a wide geographical range were compared for their morphological, gas exchange and hydraulic architecture characters. Cultivars bred for cultivation in hot and dry regions had significantly smaller leaves and crowns, but higher stomatal conductances and transpiration rates per unit of leaf area. Short-term variability in gas exchange rates was confirmed using leaf carbon isotope discrimination. A literature survey showed that, although previously unnoticed, the strong inverse coupling between leaf size and gas exchange rates was present in three other studies using the same set of cultivars. Several measures of ‘leaf-specific hydraulic conductance’ (i.e. for the whole plant and for different parts of the xylem pathway) were also linearly related to rates of water loss, suggesting that the coupling between leaf size and gas exchange was mediated by a hydraulic mechanism. It is possible that breeding for high production in hot regions has exerted a selection pressure to increase leaf-level gas exchange rates and leaf cooling. The associated reductions in leaf size may be explained by the need to maintain equilibrium between whole-plant water loss and liquid-phase hydraulic conductance.

When smaller is better: leaf hydraulic conductance and drought vulnerability correlate to leaf size and venation density across four Coffea arabica genotypes

2014 ◽  
Vol 41 (9) ◽  
pp. 972 ◽  
Author(s):  
Andrea Nardini ◽  
Eele Õunapuu-Pikas ◽  
Tadeja Savi
Keyword(s):  
Gas Exchange ◽  
Exchange Rates ◽  
Coffea Arabica ◽  
Leaf Size ◽  
Hydraulic Conductance ◽  
Climate Change Scenarios ◽  
Drought Vulnerability ◽  
Leaf Hydraulic Conductance ◽  
Vein Density ◽  
Major Vein

Leaf hydraulic conductance (Kleaf) and drought vulnerability in terms of leaf water potential inducing 50% loss of Kleaf (P50), were assessed in four genotypes of Coffea arabica L. We tested three hypotheses: (1) leaf P50 is lower in small leaves with higher vein densities; (2) lower P50 translates into lower Kleaf, limiting gas exchange rates and higher leaf mass per unit area (LMA); (3) P50 values are coordinated with symplastic drought tolerance. We found partial support for Hypotheses 1 and 3, but not for Hypothesis 2. Significant correlations existed among leaf size, vein network and drought resistance. Smaller leaves displayed higher major vein density, higher Kleaf and more negative P50. Kleaf was correlated with leaf gas exchange rates. A negative relationship was observed between Kleaf and LMA, whereas P50 was found to be positively correlated with LMA. Across coffee genotypes, reduced leaf surface area and increased vein density shifts P50 towards more negative values while not translating into higher LMA or lower Kleaf. Breeding crop varieties for both increased safety of the leaf hydraulic system towards drought-induced dysfunction and high gas exchange rates per unit of leaf area is probably a feasible target for future adaptation of crops to climate change scenarios.

Inter- and under-canopy soil water, leaf-level and whole-plant gas exchange dynamics of a semi-arid perennial C4 grass

Oecologia ◽  
2010 ◽  
Vol 165 (1) ◽  
pp. 17-29 ◽  
Author(s):  
Erik P. Hamerlynck ◽  
Russell L. Scott ◽  
M. Susan Moran ◽  
Andrea M. Schwander ◽  
Erin Connor ◽  
...  
Keyword(s):  
Gas Exchange ◽  
Soil Water ◽  
C4 Grass ◽  
Canopy Soil ◽  
Whole Plant ◽  
Leaf Level ◽  
Semi Arid ◽  
Plant Gas Exchange

scholarly journals Leaf energy balance modelling as a tool to infer habitat preference in the early angiosperms

2015 ◽  
Vol 282 (1803) ◽  
pp. 20143052 ◽  
Author(s):  
Alexandra P. Lee ◽  
Garland Upchurch ◽  
Erik H. Murchie ◽  
Barry H. Lomax
Keyword(s):  
Gas Exchange ◽  
Exchange Rates ◽  
Habitat Preference ◽  
Thermal Tolerance ◽  
Leaf Size ◽  
Cooling Capacity ◽  
Basal Angiosperms ◽  
Weedy Species ◽  
Key Aspects ◽  
Slow Growing

Despite more than a century of research, some key aspects of habitat preference and ecology of the earliest angiosperms remain poorly constrained. Proposed growth ecology has varied from opportunistic weedy species growing in full sun to slow-growing species limited to the shaded understorey of gymnosperm forests. Evidence suggests that the earliest angiosperms possessed low transpiration rates: gas exchange rates for extant basal angiosperms are low, as are the reconstructed gas exchange rates for the oldest known angiosperm leaf fossils. Leaves with low transpirational capacity are vulnerable to overheating in full sun, favouring the hypothesis that early angiosperms were limited to the shaded understorey. Here, modelled leaf temperatures are used to examine the thermal tolerance of some of the earliest angiosperms. Our results indicate that small leaf size could have mitigated the low transpirational cooling capacity of many early angiosperms, enabling many species to survive in full sun. We propose that during the earliest phases of the angiosperm leaf record, angiosperms may not have been limited to the understorey, and that some species were able to compete with ferns and gymnosperms in both shaded and sunny habitats, especially in the absence of competition from more rapidly growing and transpiring advanced lineages of angiosperms.

scholarly journals Mutations in the tomato gibberellin receptors suppresses xylem proliferation and reduces water loss under water-deficit conditions

2020 ◽  
Author(s):  
Natanella Illouz-Eliaz ◽  
Idan Nissan ◽  
Ido Nir ◽  
Uria Ramon ◽  
Hagai Shohat ◽  
...  
Keyword(s):  
Water Deficit ◽  
Water Loss ◽  
Water Status ◽  
Stomatal Closure ◽  
Normal Growth ◽  
Hydraulic Conductance ◽  
Leaf Water Content ◽  
Whole Plant ◽  
Drought Conditions ◽  
Gibberellin Activity

AbstractLow gibberellin (GA) activity in tomato (Solanum lycopersicum) inhibits leaf expansion and reduces stomatal conductance. These lead to lower transpiration and improve water status under transient drought conditions. Tomato has three GIBBERELLIN-INSENSITIVE DWARF1 (GID1) GA receptors with overlapping activities and high redundancy. We have tested whether mutation in a single GID1 reduces transpiration without affecting growth and productivity. CRISPR-Cas9 gid1 mutants were able to maintain higher leaf water content under water-deficit conditions. Moreover, while gid1a exhibited normal growth, it showed reduced whole plant transpiration and better recovery from dehydration. Mutation in GID1a inhibited xylem vessels proliferation that led to lower hydraulic conductance. In stronger GA mutants, we also found reduced xylem vessel expansion. These results suggest that low GA activity affects transpiration by multiple mechanisms; it reduces leaf area, promotes stomatal closure and reduces xylem proliferation and expansion and as a result, xylem hydraulic conductance. We further examined if gid1a perform better than the control M82 in the field. Under these conditions, the high redundancy of GID1s was lost and gid1a plants were semi-dwarf, but their productivity was not affected. Although gid1a did not perform better under drought conditions in the field, it exhibited higher harvest index.HighlightThe loss of the tomato gibberellin receptors GID1s reduced xylem proliferation and xylem hydraulic conductance. These contribute to the effect of low gibberellin activity on water loss under water-deficit condition.

scholarly journals Heterogeneity of gas exchange rates over the leaf surface in tobacco: an effect of hydraulic architecture?

2008 ◽  
Vol 31 (6) ◽  
pp. 804-812 ◽  
Author(s):  
ANDREA NARDINI ◽  
EMMANUELLE GORTAN ◽  
MATTEO RAMANI ◽  
SEBASTIANO SALLEO
Keyword(s):  
Gas Exchange ◽  
Exchange Rates ◽  
Leaf Surface ◽  
Hydraulic Architecture

Variation of leaf-level gas exchange rates and leaf functional traits of dominant trees across three successional stages in a Southeast Asian tropical forest

2021 ◽  
Vol 489 ◽  
pp. 119101
Author(s):  
Pantana Tor-ngern ◽  
Chidsanuphong Chart-asa ◽  
Wirong Chanthorn ◽  
Chadtip Rodtassana ◽  
Siriphong Yampum ◽  
...  
Keyword(s):  
Gas Exchange ◽  
Exchange Rates ◽  
Tropical Forest ◽  
Functional Traits ◽  
Southeast Asian ◽  
Leaf Functional Traits ◽  
Leaf Level ◽  
Successional Stages

scholarly journals The contribution of PIP2-type aquaporins to photosynthetic response to increased vapour pressure deficit

2021 ◽  
Author(s):  
D Israel ◽  
S Khan ◽  
C R Warren ◽  
J J Zwiazek ◽  
T M Robson
Keyword(s):  
Vapour Pressure Deficit ◽  
Air Humidity ◽  
Wild Type ◽  
Knockout Mutant ◽  
Evaporative Demand ◽  
Co2 Transport ◽  
Whole Plant ◽  
Knockout Mutants ◽  
Leaf Level ◽  
Low Humidity

Abstract The roles of different plasma membrane aquaporins (PIPs) in leaf-level gas exchange of Arabidopsis thaliana were examined using knockout mutants. Since multiple Arabidopsis PIPs are implicated in CO2 transport across cell membranes, we focused on identifying the effects of the knockout mutations on photosynthesis, and whether they are mediated through the control of stomatal conductance of water vapour (gs), mesophyll conductance of CO2 (gm) or both. We grew Arabidopsis plants in low and high humidity environments and found that the contribution of PIPs to gs was larger under low air humidity when the evaporative demand was high, whereas any effect of lacking PIP function was minimal under higher humidity. The pip2;4 knockout mutant had 44% higher gs than the wild type plants under low humidity, which in turn resulted in an increased net photosynthetic rate (Anet). We also observed a 23% increase in whole-plant transpiration (E) for this knockout mutant. The lack of functional AtPIP2;5 did not affect gs or E, but resulted in homeostasis of gm despite changes of humidity, indicating a possible role in regulating CO2 membrane permeability. CO2 transport measurements in yeast expressing AtPIP2;5 confirmed that this aquaporin is indeed permeable to CO2.

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