Effects of elevated atmospheric CO2 on leaf gas exchange response to progressive drought in barley and tomato plants with different endogenous ABA levels
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Background and aims: ABA plays an important role in modulating stomatal response to drought and elevated atmospheric CO2 (e [CO2]). This study aimed to investigate the effect of e[CO2] on the response of leaf gas exchange and plant water relations of barley and tomato plants with different endogenous ABA levels to progressive soil drying. Methods: Barley and tomato plants were grown in ambient (a[CO2], 400 ppm) and e[CO2] (800 ppm) and subjected to progressive drought stress. Wild type (WT) genotypes (Steptoe barley and AC tomato) and their ABA-deficient mutants (Az34 barley and flacca) were examined. Results: e[CO2] sensitized the photosynthetic decline with soil drying. Soil-drying induced stomatal closure was affected by [CO2] in WT genotypes, where e[CO2] sensitized stomatal closure in barley but retarded it in tomato, whereas such effects were absent in mutants. Compared to a[CO2], e[CO2] maintained leaf water potential and improved turgor pressure except in the flacca mutant. For the WT genotypes, the stomata became less sensitive to an increase in leaf ABA concentration ([ABA]leaf) under e[CO2] than a[CO2]; while for both mutants, the stomata was predominately controlled by leaf turgor and not an increase in [ABA]leaf during soil drying. Conclusion: Endogenous ABA level played an important role in modulating the effect of e[CO2] on stomatal response to soil drying. These findings improve our understanding of the mechanisms of stomatal control in monocot and dicot species responding to a future drier and CO2-enriched environment.
|Journal||Plant and Soil|
|Publication status||Published - 2020|
- ABA, Barley, CO, Drought, Stomata, Tomato