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The effect of phosphate deficiency on mitochondrial activity and adenylate levels in bean roots
Author(s) -
Rychter Anna M.,
Chauveau Michele,
Bomsel JeanLoup,
Lance Claude
Publication year - 1992
Publication title -
physiologia plantarum
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.351
H-Index - 146
eISSN - 1399-3054
pISSN - 0031-9317
DOI - 10.1111/j.1399-3054.1992.tb08768.x
Subject(s) - alternative oxidase , salicylhydroxamic acid , cyanide , respiration , mitochondrion , cytochrome c oxidase , adenylate kinase , phaseolus , biology , biochemistry , atp synthase , cellular respiration , oxidative phosphorylation , phosphate , chemistry , enzyme , botany , inorganic chemistry
Bean plants ( Phaseolus vulgaris ) were grown for 16–20 days with or without phosphate in Knop nutrient medium. It was found in previous experiments that for roots grown on a P i ‐deficient medium respiration is mainly carried out by the cyanide‐insensitive pathway. Mitochondria isolated from—P i , roots had poor respiratory control and their respiration exhibited 62% inhibition by cyanide and was inhibited (30%) by salicylhydroxamic acid (SHAM). In contrast, mitochondria obtained with control (+P i ) roots had respiratory control and ADP/O ratios typical for succinate as the substrate; their respiration was inhibited to 95% by cyanide and insensitive to SHAM. The integrity of mitochondrial membranes was similar in both types of mitochondria. Cytochrome oxidase activity, however, was about 20% lower in ‐P i mitochondria, but the cytochrome composition was the same in both types of mitochondria. The cytochrorae pathway was not operating at full capacity in mitochondria isolated from—P i roots but the alternative oxidation pathway participated in a great part in mitochondrial respiration, similar to in vivo whole roots. The participation of the non‐phosphorylating., alternative pathway decreased the respiratory control ratio in mitochondria and had an effect on the total adenine nucleotide pool and energy charge values which were lower (16 and 13% respectively) in ‐P i roots. About 50% lower ADP and 20% lower ATP levels were observed whereas AMP levels were several times higher.