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Endogenous elemental sulfur (S°) in dormant and aging α‐spores of Phomopsis viticola
Author(s) -
Beffa Trello,
Pezet Roger,
Turian Gilbert
Publication year - 1988
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.1399-3054.1988.tb05845.x
Subject(s) - biochemistry , spore , biology , endogeny , oxidase test , cytochrome c oxidase , mitochondrion , enzyme , microbiology and biotechnology
Endogenous elemental sulfur (S°) was measured in dormant α‐spores of Phomopsis viticola Sacc. (ATCC 44940) from young (25‐day‐old) and aging (105‐day‐old) cultures grown on malt extract agar medium enriched with [ 35 S]‐MgSO 4 . Endogenous S° from the mitochondrial fraction, and the lipid and aqueous cytoplasmic fractions of young and aging α‐spores were purified by column chromatography followed by thin‐layer chromatography. The purity of mitochondrial pellets were checked by the catalase (EC 1.11.1.6) and acid phosphatase (EC 3.1.3.1) activities. Activities of the mitochondrial enzymes NAD + ‐isocitrate dehydrogenase (EC 1.1.1.41) and cytochrome c oxidase (EC 1.9.3.1) were also measured to determine the distribution of the endogenous S° between mitochondria and cytoplasm. In young dormant α‐spores, endogenous S° was mostly found in the cytoplasmic lipid reserves, which were mainly phospholipids. The mitochondrial fraction of these young α‐spores contained ca 10% of the total endogenous S°, whereas in aging α‐spores stored for 105 days the endogenous S° was mainly (ca 90%) localized in the mitochondrial fraction. This accumulation of S° in mitochondria of aging α‐spores was correlated with a sharp decrease in phospholipid reserves, endogenous and exogenous respiratory activities, ATP concentration, uptake of sulfate, and NAD + ‐isocitrate dehydrogenase and cytochrome c oxidase activities. These metabolic changes were correlated with an irreversible loss of germination capacity which leads to the natural death of P. viticola α‐spores. During the first min of the breaking of dormancy, the young α‐spores possess a 7.3‐fold capacity to reduce exogenous S° with production of hydrogen sulfide, as compared to the aging α‐spores. In young α‐spores the production of hydrogen sulfide was almost totally inhibited by 40 μ M antimycin A (92%), and strongly inhibited by 2m M azide (75%) and by 15 μ M 2,4‐dinitrophenol (63%). Our work suggests that endogenous S° plays a key role in the regulation of the dormancy and aging processes of α‐spores of P. viticola .