Variation in mesophyll conductance among Australian wheat genotypes

Jahan, Eisrat; Amthor, Jeffrey S.; Farquhar, Graham D.; Trethowan, Richard; Barbour, Margaret M.

doi:10.1071/fp13254

Cited by 54 publications

(73 citation statements)

References 42 publications

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“…Consistent with some recent studies (Barbour et al, 2010(Barbour et al, , 2016Galmés et al, 2011;Gu et al, 2012;Giuliani et al, 2013;Jahan et al, 2014), we found strong support for the relationship between A N and g m . g m is reported to respond to environmental stimuli and stress at time scales ranging from seconds to seasons (Bernacchi et al, 2002;Grassi and Magnani, 2005;Galmés et al, 2007;von Caemmerer and Evans, 2015;Sorrentino et al, 2016).…”

Section: Discussionsupporting

confidence: 82%

“…We found no significant relationship between A N /g s and g m ( Figs. 2A and 5A); this is consistent with results in rice (Giuliani et al, 2013) and wheat (Jahan et al, 2014), while a negative correlation was found in well-watered and water-stressed tomato (see Supplemental Table S1 in Galmés et al, 2011). The disparity between the prevailing assumption that enhancing g m will improve A N /g s (Flexas et al, 2013a and data inconsistent with this idea stems from the correlation between g m and g s reported here (Figs.…”

Section: Discussionsupporting

confidence: 79%

“…A positive relationship between g m and g s has been reported in several studies (Barbour et al, 2010;Gu et al, 2012;Flexas et al, 2013aFlexas et al, , 2013b, although two studies in wheat (Triticum aestivum) detected no relationship between g m and g s (Jahan et al, 2014;Barbour et al, 2016). It is not yet clear if the coordination between g m and g s is associated with the independent scaling of both diffusional conductances with the overall physiological activity of leaves or if there is an underlying mechanistic relationship we have yet to appreciate (e.g.…”

mentioning

confidence: 95%

“…Another study in rice found nearly 60% variation among 11 inbred lines (Gu et al, 2012). In wheat, 2-fold variation was found among 10 genotypes (Jahan et al, 2014) and 3-fold variation among 150 mapping population lines (Barbour et al, 2016). Clearly, genetic variation for g m exists in the monocots, although in 2014, half of the world's 10 most planted (as total area) crops were eudicots (FAOSTAT 2016; http://faostat3.fao.org/ download/Q/QC/E).…”

mentioning

confidence: 99%

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Variable Mesophyll Conductance among Soybean Cultivars Sets a Tradeoff between Photosynthesis and Water-Use-Efficiency

Tomeo

Rosenthal

2017

Plant Physiol.

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Photosynthetic efficiency is a critical determinant of crop yield potential, although it remains below the theoretical optimum in modern crop varieties. Enhancing mesophyll conductance (i.e. the rate of carbon dioxide diffusion from substomatal cavities to the sites of carboxylation) may increase photosynthetic and water use efficiencies. To improve water use efficiency, mesophyll conductance should be increased without concomitantly increasing stomatal conductance. Here, we partition the variance in mesophyll conductance to within-and among-cultivar components across soybean (Glycine max) grown under both controlled and field conditions and examine the covariation of mesophyll conductance with photosynthetic rate, stomatal conductance, water use efficiency, and leaf mass per area. We demonstrate that mesophyll conductance varies more than 2-fold and that 38% of this variation is due to cultivar identity. As expected, mesophyll conductance is positively correlated with photosynthetic rates. However, a strong positive correlation between mesophyll and stomatal conductance among cultivars apparently impedes positive scaling between mesophyll conductance and water use efficiency in soybean. Contrary to expectations, photosynthetic rates and mesophyll conductance both increased with increasing leaf mass per area. The presence of genetic variation for mesophyll conductance suggests that there is potential to increase photosynthesis and mesophyll conductance by selecting for greater leaf mass per area. Increasing water use efficiency, though, is unlikely unless there is simultaneous stabilizing selection on stomatal conductance.

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Section: Discussionsupporting

confidence: 82%

Section: Discussionsupporting

confidence: 79%

mentioning

confidence: 95%

mentioning

confidence: 99%

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Variable Mesophyll Conductance among Soybean Cultivars Sets a Tradeoff between Photosynthesis and Water-Use-Efficiency

Tomeo

Rosenthal

2017

Plant Physiol.

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“…Mesophyll conductance, which is defined as the movement of CO2 from the sub-stomatal cavity across the leaf mesophyll cells into the chloroplasts (Niinemets et al, 2009), plays an important role in controlling rates of photosynthesis (Keenan et al, 2010), and intrinsic TE, as was reported in pearl millet (Barbour et al, 2010). Similar studies in wheat reported genotypes with high photosynthesis and intrinsic water use efficiency (Jahan et al, 2014). Since gm accounts for movement of CO2 into leaf carboxylation sites, gm differences result in differences within and amongst crops for photosynthesis (Niinemets et al, 2009) and, potentially for intrinsic TE.…”

supporting

confidence: 52%

Role of leaf photosynthesis and stomatal conductance in determining the genotypic variation in whole-plant Transpiration Efficiency (TE) in Sorghum

Geetika¹

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Traits such as transpiration efficiency (TE) that are influenced by plant water use can be used to characterise the adaptability of crops to specific growth environments. TE is defined as the amount of biomass produced per unit of water used, and can ensure continued crop production in droughtprone regions. Where TE is associated with reduced use of soil water during the vegetative growth phase, water availability during grain filling may be greater, which can delay the onset of drought stress and increase grain yield under water-limited conditions. This may become even more pertinent with predicted increases in severity and frequency of droughts with climate change. The aims of this study were to firstly dissect TE into its leaf-level physiological components to better understand the effects of genetic variation in these components on TE in sorghum. Secondly, to examine whether TE responses observed under well-watered conditions were preserved under drought, and whether transpiration response was an adaptive response to drought. Twenty-seven genotypes were screened for TE under well-watered conditions using a fully automated lysimetry platform to obtain accurate plant water use data. To determine whether variation in TE among these genotypes was associated with differences in maximum photosynthesis (Amax) or leaf conductance (g) we measured the net carbon assimilation rate of the second last fully expanded leaf at high light intensity, using an infrared gas analyser, and leaf water flux was measured using a porometer, as a proxy for conductance. Genotypic variation in TE among the sorghum germplasm used was mainly associated with differences in the response of transpiration rates to vapour pressure deficit (VPD).Genotypes with low transpiration rates per unit green leaf area (T/GLA) tended to have high TE.Variation in Amax explained some of the differences in TE that could not be explained by T/GLA and may have been a result of mechanisms associated with differences in biochemical pathways that affect the efficiency of conversion of CO2 into photosynthate. While drought tended to increase TE, genotypic variation in TE was largely conserved. However, the response of transpiration rates to drought stress differed across genotypes, with some genotypes showing reduced T/GLA under drought when VPD was high, whereas others did not. These contrasting responses were associated with differences in stomatal responses to drought stress, such that some genotypes were better able to conserve water under drought stress than others. This adaptive response was not related to TE per se and may have important implications for adaptation to drought stress. Hence, the phenotyping of sorghum lines using the associated physiological traits underpinning TE differences is beneficial in identifying traits that may support growth in certain environments and can optimise grain yield production under water-limited conditions. III Declaration by AuthorThis thesis is composed of my original work, and contains no material previously ...

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Modelling QTL-Trait-Crop Relationships: Past Experiences and Future Prospects

Yin¹,

Struik²,

et al. 2016

Crop Systems Biology

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Variation in mesophyll conductance among Australian wheat genotypes

Cited by 54 publications

References 42 publications

Variable Mesophyll Conductance among Soybean Cultivars Sets a Tradeoff between Photosynthesis and Water-Use-Efficiency

Variable Mesophyll Conductance among Soybean Cultivars Sets a Tradeoff between Photosynthesis and Water-Use-Efficiency

Role of leaf photosynthesis and stomatal conductance in determining the genotypic variation in whole-plant Transpiration Efficiency (TE) in Sorghum

Modelling QTL-Trait-Crop Relationships: Past Experiences and Future Prospects

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