Species-specific enzymatic tolerance of sulfide toxicity in plant roots

• Published in: Plant physiology and biochemistry Vol. 88; pp. 36 - 41
• Main Authors: Martin, Nicole M., Maricle, Brian R.
• Format: Journal Article
• Language: English
• Published: France Elsevier Masson SAS 01.03.2015
• Subjects: Adaptation, Physiological; Alcohol dehydrogenase; Alcohol Dehydrogenase - metabolism; Cytochrome c oxidase; Ecosystem; Electron Transport Complex IV - metabolism; Estuaries; Estuarine plants; Flooding-sensitive plants; Flooding-tolerant plants; Floods; Mitochondria - drug effects; Oxidation-Reduction; Plant Proteins - metabolism; Plant Roots - drug effects; Plant Roots - enzymology; Plants - drug effects; Plants - enzymology; Plants - genetics; Respiration; Species Specificity; Stress, Physiological; Sulfide; Sulfides - adverse effects; Sulfides - metabolism; Water; Cytochrome c oxidase; Sulfide; Flooding-tolerant plants; Estuarine plants; Alcohol dehydrogenase; Respiration; Flooding-sensitive plants
• ISSN: 0981-9428; 1873-2690
• DOI: 10.1016/j.plaphy.2015.01.007

Toxic effects of sulfide come from a poisoning of a number of enzymes, especially cytochrome c oxidase, which catalyzes the terminal step in mitochondrial aerobic respiration. Despite this, some estuarine plants live in sulfide-rich sediments. We hypothesized estuarine and flooding-tolerant species might be more tolerant of sulfide compared to upland species, and this was tested by measures of root cytochrome c oxidase and alcohol dehydrogenase activities in extracts exposed to sulfide. Enzyme activities were measured in 0, 5, 10, 15, and 20 μM sodium sulfide, and compared among 17 species of plants. Activities of alcohol dehydrogenase and cytochrome c oxidase were both reduced by increasing sulfide concentration, but cytochrome c oxidase was more sensitive to sulfide compared to alcohol dehydrogenase. Activities of cytochrome c oxidase were reduced to near zero at 5–10 μM sulfide whereas alcohol dehydrogenase activities were only reduced by about 50% at 10 μM sulfide. All species were sensitive to increasing sulfide, but to different degrees. Cytochrome c oxidase in flooding-sensitive species was decreased to near zero activity at 5 μM sulfide, whereas activities in some flooding-tolerant species were still detectable until 15 μM sulfide. Cytochrome c oxidase activities in some estuarine species were low even in the absence of sulfide, perhaps an adaptation to avoid sulfide vulnerability in their native, sulfide-rich habitat. This illustrates the potent metabolic effects of sulfide, and this is the first demonstration of varying sensitivities of cytochrome c oxidase to sulfide across organisms, making these data of novel importance. •We compared sulfide toxicity among 17 plant species adapted to different habitats.•We investigated effects of sulfide on two enzymes of respiration in plant roots.•There are varying sensitivities of cytochrome c oxidase to sulfide across species.•Estuarine species have cytochrome c oxidase that is more tolerant of sulfide.•Alcohol dehydrogenase is less sensitive to sulfide.