Mitochondrial Modifications Associated with the Cytoplasmic Male Sterility in Faba Beans

Abstract

Isolated mitochondria of faba beans carrying two different determinisms of the cytoplasmic male sterility (cytoplasms 447 and 350) have been compared to fertile lines.1. In addition to the major mitochondrial DNA, five small DNA species (in the range of 1000-2000 base pairs) were detected by agarose gel electrophoresis in the four cytoplasms. An additional small D N A species was found specifically in the cytoplasm 350. After endonuclease restriction of the mitochondrial DNA, the patterns obtained for both male-sterile cytoplasms were identical to each other but distinct by two to four fragments from the patterns obtained for male-fertile cytoplasms.2.[3sS]Methionine labeling in situ of the mitochondrial protein synthesis revealed an additional polypeptide (M, = 25000) detected only in the two male-sterile cytoplasms.3. The male-sterile cytoplasm 350 showed a decrease of the respiratory state 3 of oxygen uptake during oxidation of NADH or malate + pyruvate. This decrease is thought to reflect a smaller capacity of the respiratory chain. These specific mitochondrial modifications support the hypothesis of a mitochondrial localization of the cytoplasmic male sterility determinant in faba beans.Little is known concerning the molecular interactions between the nuclear and the cytoplasmic genetic information in plants. One of the best studied systems is that of cytoplasmic male sterility, a powerful tool for the commercial production of hybrids. The mitochondrial inheritance of cytoplasmic male sterility is well supported in maize by different biochemical observations. (a) Restriction analysis of the isolated mitochondrial D N A shows specific modifications in malesterile cytoplasms [1,2]. (b) Kemble and Bedbrook have reported the presence in mitochondria of small linear and circular DNA molecules, the number and the size of which are specific for each cytoplasm [3]. (c) Radioactive labeling of the mitochondrial protein synthesis shows that each malesterile cytoplasm contains an additional polypeptide of a specific molecular weight [4], the synthesis of which is under the control of nuclear restorer genes that suppress the malesterile phenotype [5]. (d) The toxin produced by Helminthosporium muydis (race T), responsible for the blighting of the plants carrying the cytoplasmic male sterility of T-type, affects specifically the functions of the mitochondria isolated from that cytoplasm [6].Modifications of the restriction patterns of mitochondrial DNA from cytoplasmic male-sterile lines of wheat [7] and tobacco [S] also suggest the involvement of mitochondria in the species analyzed. In order to establish whether the mitochondrial inheritance hypothesis of the cytoplasmic male sterility can be generalized to other species, we have characterized the two male-sterile cytoplasms presently available in faba beans (Viciu faba L.). The cytoplasm 447, first described by Bond et al. [9] expresses the male-sterile phenotype when associated with a recessive maintainer gene. In these conditions, the male-sterile plant cells cont...

Bax directly induces release of cytochrome c from isolated mitochondria

“…Female rats were killed by decapitation, and mitochondria were purified from the liver by differential centrifugation and separation on a sucrose gradient (26). Mitochondria were suspended at 10 mg protein͞ml in MSB (400 mM mannitol͞50 mM Tris⅐HCl, pH 7.2͞5 mg/ml BSA͞10 mM KH 2 PO 4 ) and kept on ice for up to 4 hr.…”

Recent Developments in Breeding Field Beans (Vicia faba L.)

“…and GARGER (1981) also refer to high molecular weight RNA that has been isolated from sterile cytoplasm and associated with the CSB. A hypothesis of mitochondrial control of CMS •was proposed by LE GUEN and BERVILLE (1974), and the different restriction patterns of BOND mitochondria] DNA in CMS and male fertile counterparts reported by BOUTRY and BRIQUET (1982) strongly suggest a mkochondrial localization of CMS determinants. Moreover, as might be expected, a small DNA species was peculiar to 350 cytoplasm and GOBLET et al (1983) distinguished 350 CMS from fertiles and from 447 CMS bv a supercoiled DNA molecule.…”

Atractyloside‐induced release of cathepsin B, a protease with caspase‐processing activity

“…Mitochondria were isolated from Wistar rat hepatocytes (8 weeks, male) as described in [26]. They were then further puri¢ed on a Percoll gradient (Pharmacia Biotech, Uppsala, Sweden) as described in [27], and were ¢nally washed and resuspended in cell free system (CFS) bu¡er [17] and used immediately.…”