Stomatal Regulation and Osmotic Adjustment in Sorghum in Response to Salinity

Abstract

Sorghum bicolor (L.) Moench, one of the most important dryland cereal crops, is moderately tolerant of soil salinity, a rapidly increasing agricultural problem due to inappropriate irrigation management and salt water intrusion into crop lands as a result of climate change. The mechanisms for sorghum’s tolerance of high soil salinity have not been elucidated. This study tested whether sorghum plants adapt to salinity stress via stomatal regulation or osmotic adjustment. Sorghum plants were treated with one of seven concentrations of NaCl (0, 20, 40, 60, 80, or 100 mM). Leaf gas exchange (net CO2 assimilation (A), transpiration (Tr); stomatal conductance of water vapor (gs), intrinsic water use efficiency (WUE)), and water (Ψw), osmotic (Ψo), and turgor Ψt potentials were evaluated at 40 days after the imposition of salinity treatments. Plants exhibited decreased A, gs, and Tr with increasing salinity, whereas WUE was not affected by NaCl treatment. Additionally, plants exhibited osmotic adjustment to increasing salinity. Thus, sorghum appears to adapt to high soil salinity via both osmotic adjustment and stomatal regulation.

Combined transcriptomic and physiological metabolomic analyses elucidate key biological pathways in the response of two sorghum genotypes to salinity stress

“…indicator of photosynthetic function (Xu et al, 2008;Dourado et al, 2022). It has been found that the chlorophyll level of plants decreases with aggravated salt stress (Pires et al, 2015;Rachoski et al, 2015;Dabrowski et al, 2016).…”

“…Similar to our results, Nxele found that salinity stress could reduce water retention in sorghum plants ( Nxele et al., 2017 ), which is a common response to salt stress. Under adverse circumstances, the chlorophyll level in the plant is a good indicator of photosynthetic function ( Xu et al., 2008 ; Dourado et al., 2022 ). It has been found that the chlorophyll level of plants decreases with aggravated salt stress ( Pires et al., 2015 ; Rachoski et al., 2015 ; Dąbrowski et al., 2016 ).…”

Progress of Research on the Physiology and Molecular Regulation of Sorghum Growth under Salt Stress by Gibberellin

“…A study on salt tolerance mechanisms in sorghum revealed that 84 differentially expressed genes ( DEGs ) are associated with photosynthesis in salt-tolerant crops after salt stress. During stomatal regulation and osmotic adjustment in sorghum in response to salinity [ 93 ], up to 51 genes are related to chlorophyll synthesis; most DEGs are related to chlorophyll, PS II, and cytochrome, and all the DEGs related to ATP synthase and carbon fixation are upregulated [ 95 ]. This suggests that salt stress can induce photosynthetic response genes in crops, and these genes related to photosynthetic electron transport may be activated by strong light energy conversion [ 96 ].…”

Drought stress tolerance mechanisms and their potential common indicators to salinity, insights from the wild watermelon (Citrullus lanatus): A review

“…The response time of stomata during the critical period is very important in the survival of plants during drought and salinity stress, the quicker the plants respond, the better position they are in avoiding stress effects. This has been associated with the ability to withstand drought in phaseolus ( Markhart, 1985 ) cowpea ( Laffray and Louguet, 1990 ), sorghum ( Tsuji et al., 2013 ), soybean ( Hossain et al., 2015 ) and woody species ( Yan et al., 2017 ); salinity in maize ( Neto et al., 2004 ), Cotton ( Janagoudar, 2007 ), sorghum ( Duarado et al., 2022 ), Eruca sativa ( Hniličková et al., 2017 ). This was attributed to stomatal closure as a form of salinity stress coping mechanism.…”