Changes in the Respiratory, Enzymatic, and Swelling and Contraction Properties of Mitochondria from Colytedons of Phaseolus vulgaris L. during Germination

Abstract

Mitochondria isolated from cotyledons of germinating wax beans (Phaseolus vulgaris L.) showed fairly good respiratory control on days 1 and 2 after planting. The respiratory control was completely lost from days 3 to 5. During this period mitochondria were shown to be very leaky, losing about 88% of their total nicotinamide adenine dinucleotide to the suspending medium in a short time. The respiratory control was partially recovered by day 7, after which it completely disappeared again. By the use of differential centrifugation, the mitochondria were divided into subfractions by sequential centrifugation: 10,000g for 5 minutes, 25,000g for 5 minutes, and 40,000g for 5 minutes. The 10,000g subfraction was responsible for the recovery of mitochondrial activity (respiratory control value, adenosine diphosphate to oxygen ratio, and rate of oxygen utilization), on day 7. Activities of succinate dehydrogenase, cytochrome oxidase, pyruvate dehydrogenase, and isocitrate dehydrogenase from different mitochondrial subfractions of aging cotyledons were determined. In general, the enzyme activities, adenosine diphosphate to oxygen ratios, and the ability of mitochondria to swell and contract followed the same pattern as for respiratory control.Previous research has shown that the cotyledons of germinating seedlings and other plant tissues go through many biochemical changes at the subcellular level during aging (1,4,12,16,21,25,28). Lado and Schwendimann (16) showed that in castor bean endosperm, mitochondrial proteins and enzyme activities decrease rapidly during seed maturation, while other workers (1) observed a rapid increase during the earliest part of germination. Opik (21) studied the changes in respiration rate and mitochondrial activity in bean cotyledons. She found that while oxygen uptake of the intact cotyledons rose to a peak between the 3rd and 5th days of germination, mitochondrial activity decreased from 36 hr onwards and in most of the storage cells mitochondrial cristae had become swollen and matrix had darkened by the 3rd day. Since the mitochondria are highly important as centers of energy production, one would expect changes in the physiological state of cotyledons to be reflected in the mitochondrial activity. This report concerns the changes in the bean cotyledon mitochondrial activity with aging. The mitochondrial activity is measured by the ability of mitochondria to oxidize different substrates and to swell and contract, and by the activities of various mitochondrial enzymes. MATERIAIS AND METHODSThe bean seeds (Phaseolus vulgaris L. var. Kinghorn wax) were soaked in running tap water for 4 hr and then planted in vermiculite (horticulture grade). The seedlings were grown in the dark at 27 C. The cotyledons from the germinating seedlings were removed at the required age, washed with deionized water, and used as the source of mitochondria. Mitochondria were prepared from about 50 g of cotyledons by the following method: the cotyledons were gently crushed with a mortar and pestle for 90 sec in...

Membrane integrity and oxidative properties of mitochondria isolated from imbibing pea seeds after priming or accelerated ageing

“…Observations of cell ultrastructure during seed development led to a general view of poorly differentiated mitochondria in quiescent tissue that evolve, upon imbibition, into healthy looking mitochondria with well-defined cristae and a dense matrix (Bain and Mercer, 1966a, b;Morohashi et al, 1981a). Changes in mitochondrial activities (substrate oxidations, ADP/O) during germination, which were monitored using crude preparations of mitochondria, supported the general trend of improvement suggested by cytological observations (Kollöffel and Sluys, 1970;Malhotra and Spencer, 1970;Asahi, 1971, 1973;Solomos et al, 1972;Morohashi and Shimokoriyama, 1975;Morohashi and Bewley, 1980 a, b;Morohashi et al, 1981a). Biogenesis of mitochondria during germination is expected to proceed from structural development of pre-existing mitochondria in starch-storing seeds and from de novo synthesis of mitochondria in lipid-storing seeds (Malhotra and Spencer, 1973;Morohashi et al, 1981a, b;Morohashi, 1986).…”

Oligo-Carrageenans Stimulate Growth by Enhancing Photosynthesis, Basal Metabolism, and Cell Cycle in Tobacco Plants (var. Burley)

“…In particular, oligo-carrageenans induced the activation of PDH and IDH, which are NADHsynthesizing enzymes of the Krebs cycle, located in mitochondria (Malhotra and Spencer 1970). In addition, they induced the activation of the NADH-synthesizing enzyme glyceraldehyde 3-phosphate dehydrogenase (data not shown) located in chloroplasts and in the cytoplasm (Winter and others 1982).…”

Respiratory Properties of Mitochondria from Rice Seedlings Germinated under Water and Their Changes during Air Adaptation

“…These results suggest that the deficiency of NAD+ may limit the oxidation of malate in submerged mitochondria, and this defect may be removed during air adaptation. Mitochondria from cotyledons of wax beans during germination were shown to be very leaky in vitro, losing about 88% of their total NAD to the suspending medium in a short time (11). Our mitochondria from submerged seedlings showed good integrity of the outer membrane, judging from the succinate:Cyt c oxidoreductase activity.…”