Respiration in Cells and Mitochondria of Male-Fertile and Male-Fertile and Male-Sterile Nicotiana spp.

Abstract

Three cytoplasmic male-sterile Nicotiana cultivars together with corresponding male-fertile progenitors and restored lines were investigated in order to find possible correlations between respiratory characteristics and male sterility. Oxygen consumption measurements were performed on cells from suspension cultures as well as on mitochondria isolated from green leaves. Inhibitors, which have been reported to specifically block either the cytochrome (KCN) or the alternative (propyl gallate and salicylhydroxamic acid [SHAM] respiratory pathways, were used in order to measure the capacity and activity of the two pathways. One of the inhibitors, SHAM, was found unsuitable to measure the activity of the altemative pathway due to the lack of specificity of SHAM for this pathway. A great difference in the capacity of the alternative pathway was detected between the two types of cell materials tested. Mitochondria isolated from green leaves showed a capacity of the alternative pathway of 5 to 20% of total mitochondrial repiration, while the capacity of cells from suspension cultures generally ranged from 50 to 80%. In addition to this, in organello synthesis of mitochondrial proteins revealed differences between mitochondria isolated from green leaves and from cell suspensions. No correlation, however, could be found between respiratory characteristics and male sterility.

Lack of mitochondrial and nuclear-encoded subunits of complex I and alteration of the respiratory chain in Nicotiana sylvestris mitochondrial deletion mutants

“…8) in CMS mutants have a physiological role. Our results clearly distinguish N. sylvestris mutants from other CMS mutants; the AOX pathway in the latter was unchanged or, at most, slightly inhibited when compared with fertile plants (34)(35)(36)(37)(38).…”

“…A second branching point occurs at ubiquinone, where electrons may pass either through the main cytochrome pathway or through AOX, which is insensitive to cyanide. Its involvement in the CMS trait has been suggested for various species (34)(35)(36)(37)(38).…”

Cytoplasmic Male Sterility in Higher Plants

“…h1 Nicotiana no ditl'erences in electron transport were detected in leaves and suspension cultures of CMS. fertile and fertility-restored lines ( 24 ). h1 petunia, however.…”