Abstract
Photosynthesis limitation by CO2 flow constraints from sub-stomatal cavities to carboxylation sites in chloroplasts under drought stress conditions is, at least in some plant species or crops not fully understood, yet. Leaf mesophyll conductance for CO2 (gm) may considerably affect both photosynthesis and water use efficiency (WUE) in plants under drought conditions. The aim of our study was to detect the responses of gm in leaves of four winter wheat (Triticum aestivum L.) genotypes from different origins under long-term progressive drought. Based on the measurement of gas-exchange parameters the variability of genotypic responses was analyzed at stomatal (stomata closure) and non-stomatal (diffusional and biochemical) limits of net CO2 assimilation rate (AN). In general, progressive drought caused an increasing leaf diffusion resistance against CO2 flow leading to the decrease of AN, gm and stomatal conductance (gs), respectively. Reduction of gm also led to inhibition of carboxylation efficiency (Vcmax). On the basis of achieved results a strong positive relationship between gm and gs was found out indicating a co-regulation and mutual independence of the relationship under the drought conditions. In severely stressed plants, the stomatal limitation of the CO2 assimilation rate was progressively increased, but to a less extent in comparison to gm, while a non-stomatal limitation became more dominant due to the prolonged drought. Mesophyll conductance (gm) seems to be a suitable mechanism and parameter for selection of improved diffusional properties and photosynthetic carbon assimilation in C3 plants, thus explaining their better photosynthetic performance at a whole plant level during periods of drought.
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Claims 9
Claim · model-written summary
Progressive drought increased leaf diffusion resistance to CO2 flow in winter wheat.
- Taxon
- Wheat
Triticum aestivumt0 - Treatment
- progressive droughte0
- Outcome
- leaf diffusion resistance against CO2 flowe0
- Direction
- increasinge0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Wheat”
e0“progressive drought caused an increasing leaf diffusion resistance against CO2 flow”
Claim · model-written summary
Progressive drought decreased net CO2 assimilation rate in winter wheat.
- Taxon
- WheatTriticum aestivumt0
- Treatment
- progressive droughte0
- Outcome
- ANe0
- Direction
- decreasee0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Wheat”
e0“progressive drought caused an increasing leaf diffusion resistance against CO2 flow leading to the decrease of AN, gm and stomatal conductance (gs)”
Claim · model-written summary
Progressive drought decreased mesophyll conductance in winter wheat.
- Taxon
- WheatTriticum aestivumt0
- Treatment
- progressive droughte0
- Outcome
- gme0
- Direction
- decreasee0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Wheat”
e0“progressive drought caused an increasing leaf diffusion resistance against CO2 flow leading to the decrease of AN, gm and stomatal conductance (gs)”
Claim · model-written summary
Progressive drought decreased stomatal conductance in winter wheat.
- Taxon
- WheatTriticum aestivumt0
- Treatment
- progressive droughte0
- Outcome
- stomatal conductance (gs)e0
- Direction
- decreasee0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Wheat”
e0“progressive drought caused an increasing leaf diffusion resistance against CO2 flow leading to the decrease of AN, gm and stomatal conductance (gs)”
Claim · model-written summary
Reduced mesophyll conductance inhibited carboxylation efficiency in winter wheat.
- Taxon
- WheatTriticum aestivumt0
- Outcome
- carboxylation efficiency (Vcmax)e0
- Qualifier
- Reduction of gme0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Wheat”
e0“Reduction of gm also led to inhibition of carboxylation efficiency (Vcmax)”
Claim · model-written summary
Mesophyll conductance and stomatal conductance were strongly positively related during drought in winter wheat.
- Taxon
- WheatTriticum aestivumt0
- Outcome
- gme0
- Direction
- positivee0
- Qualifier
- under the drought conditionse0
- Comparator
- gse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Wheat”
e0“a strong positive relationship between gm and gs was found out indicating a co-regulation and mutual independence of the relationship under the drought conditions”
Claim · model-written summary
Stomatal limitation of CO2 assimilation increased in severely stressed winter wheat plants, but less than mesophyll limitation.
- Taxon
- WheatTriticum aestivumt0
- Outcome
- stomatal limitation of the CO2 assimilation ratee0
- Direction
- increasede0
- Qualifier
- severely stressed plantse0
- Comparator
- gme0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Wheat”
e0“In severely stressed plants, the stomatal limitation of the CO2 assimilation rate was progressively increased, but to a less extent in comparison to gm”
Claim · model-written summary
Non-stomatal limitation became more dominant with prolonged drought in winter wheat.
- Taxon
- WheatTriticum aestivumt0
- Outcome
- non-stomatal limitatione0
- Direction
- more dominante0
- Qualifier
- prolonged droughte0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Wheat”
e0“a non-stomatal limitation became more dominant due to the prolonged drought”
Claim · model-written summary
The authors proposed mesophyll conductance as a selection parameter for improved diffusion and carbon assimilation under drought.
- Taxon
- WheatTriticum aestivumt0
- Outcome
- parameter for selection of improved diffusional properties and photosynthetic carbon assimilatione0
- Qualifier
- during periods of droughte0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“Wheat”
e0“Mesophyll conductance (gm) seems to be a suitable mechanism and parameter for selection of improved diffusional properties and photosynthetic carbon assimilation in C3 plants, thus explaining their better photosynthetic performance at a whole plant level during periods of drought”
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