Interactive Effects of Abiotic Stress and Elevated CO2 on Physio-Chemical and Photosynthetic Responses in Suaeda Species

• Published in: Journal of plant growth regulation 2022-10, Vol.41 (7), p.2930-2948
• Main Authors: Haque, Md Intesaful, Siddiqui, Shahrukh A., Jha, B., Rathore, Mangal S.
• Format: Article
• Language: English
• Subjects: Abiotic stress; Accumulation; Agriculture; Biomedical and Life Sciences; Carbon dioxide; Carbon dioxide fixation; Chemical analysis; Chlorophyll; Damage accumulation; Electron transfer; Fixation; Halophytes; Life Sciences; Malate dehydrogenase; Malic enzyme; Osmotic stress; Oxidative stress; Photosynthesis; Photosystem II; Plant Anatomy/Development; Plant Physiology; Plant Sciences; Polyethylene glycol; Reactive oxygen species; Rehabilitation; Salinity; Salinity effects; Saprolegnia monoica; Seawater; Sodium chloride; Suaeda; Water analysis
• ISSN: 0721-7595; 1435-8107
• DOI: 10.1007/s00344-021-10485-1

Suaeda fruticosa and S. monoica are important halophytes for ecological rehabilitation of saline lands. We report differential physio-chemical, photosynthetic, and chlorophyll fluorescence responses in these halophytes under 100 mM sodium chloride (NaCl), 50% strength (16.25 ppt) of seawater (SW)-imposed salinity, and 10% polyethylene glycol 6000 imposed osmotic stress at 380 (ambient) and 1200 (elevated) µmol mol –1 CO 2 concentrations. SW salinity enhanced the growth in both species; however, compared with S. fruticosa, the S. monoica exhibited comparatively better growth and biomass accumulation under saline conditions at elevated CO 2 . Results demonstrated better photosynthetic performances of S. monoica under stress conditions at both levels of CO 2 , and this resulted in higher accumulation of carbon, nitrogen, sugar, and starch contents. S. monoica exhibited improved antenna size, electron transfer at PSII donor side, and efficient working of photosynthetic machinery at elevated CO 2 , which might be due to efficient upstream utilization of reducing power to fix the CO 2 . The δ 13 C results supported the operation of C 4 CO 2 fixation in S. monoica and C 3 or intermediate pathway of CO 2 fixation in S. fruticosa . Lower accumulation of reactive oxygen species, reduced membrane damage, lowered solute potential, and higher accumulation of proline and polyphenol contents indicated elevated CO 2 -induced abiotic stress tolerance in Suaeda . Higher activity of antioxidant enzymes in both species at both levels of CO 2 help plants to combat the oxidative stress. Upregulation of NADP-dependent malic enzyme and NADP-dependent malate dehydrogenase genes indicated their role in abiotic stress tolerance as well as photosynthetic carbon (C) sequestration. Operation of C 4 type CO 2 fixation in S. monoica and an intermediate CO 2 fixation in S. fruticosa could be the possible reason for the superior photosynthetic efficiency of S. monoica under stress conditions at elevated CO 2 .