The Mechanism of Ethylene and Cyanide Action in Triggering the Rise in Respiration in Potato Tubers

Solomos, T.; Laties, George G.

doi:10.1104/pp.55.1.73

Cited by 96 publications

(52 citation statements)

References 23 publications

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“…This activity is thought to be due to an electron flow which does not involve Cyt oxidase (2,10). We present data which show that initial in vivo 02 uptake by soybeans is not inhibited by KCN and is inhibited by hydroxamate; and that this apparent respiration may be due in part to the activity of lipoxygenase, an enzyme which catalyzes the dioxygenation of certain unsaturated fatty acids (5 emulsion in 10 mm phosphate buffer (pH 7.0) (11).…”

mentioning

confidence: 62%

Confounding of Alternate Respiration by Lipoxygenase Activity

Parrish¹,

Leopold²

1978

Plant Physiol.

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The initial burst of respiratory activity (Qo2) of Neither the biochemical nature nor the physiological significance of the cyanide-insensitive, alternate respiration is known, but its activity has now been demonstrated in a number of plant systems (2, 9) Alternate respiration is commonly defined or diagnosed as that portion of respiration which is insensitive to cyanide but inhibited by hydroxamic acids (2,8). This activity is thought to be due to an electron flow which does not involve Cyt oxidase (2, 10). We present data which show that initial in vivo 02 uptake by soybeans is not inhibited by KCN and is inhibited by hydroxamate; and that this apparent respiration may be due in part to the activity of lipoxygenase, an enzyme which catalyzes the dioxygenation of certain unsaturated fatty acids (5). emulsion in 10 mm phosphate buffer (pH 7.0) (11). A I mg/ml (3.56 mM) LA solution was used as substrate for the LOX assays. LOX was dissolved in 10 mm phosphate buffer (pH 7.0) and injected into the 02 electrode reaction vessel to give a reaction mixture which had 100 ,ug of LOX/ml. Assuming a mol wt of about 100,000 (1), LOX concentration was about I ,UM. MATERIALS AND METHODS RESULTS AND DISCUSSIONThe respiration of soybean particles was characterized by a burst of 02 consumption during the first few min of imbibition (6). This respiratory burst was not inhibited by KCN and was inhibited by SHAM (Fig. 1). The initial respiratory activity was also markedly inhibited by PG (Fig. 2), being about 10 times more sensitive to PG than to SHAM. If the normally alkaline KCN solution was strongly buffered (100 mM) to maintain the pH at neutrality, the small promotion of respiration seen in Figure 1 was no longer observed; and there was still no evidence of inhibition in the first few min. SHAM and PG sensitivities were not affected by buffering at pH 7.0.Suspecting that the SHAM inhibition might be related to LOX activity, we tested the cell-free enzyme's sensitivity to the hydroxamate and found (Fig. 3) that indeed it was, being 90%o inhibited by 5 mm SHAM. Autooxidation of LA (in the absence of LOX) was unaffected by SHAM. The LOX activity was not inhibited by KCN (data not shown). The enzyme was about 10 times more sensitive to PG than to SHAM, being 90%o inhibited at about 0.5 mM PG (data not shown).To investigate further the possible role of LOX in the apparent initial respiration, soybean seed particles were placed in buffered solution with or without SHAM and 02 uptake was measured with and without the addition of 50 jig/ml (0.18 mM) LA substrate (Fig. 4). In the absence of SHAM, when LA was added, there was an immediate 9-to 10-fold increase in respiratory rate and all of the 02 remaining in the solution was quickly consumed. When 5 mM SHAM was present, the initial 02 consumption was inhibited approximately 50%1b, and the addition of LA caused only a transient 2-to 3-fold increase in 02 consumption. (Added Tween 20 was without effect on the respiration rates in the presence of absence of hydroxamate.) The m...

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mentioning

confidence: 62%

Confounding of Alternate Respiration by Lipoxygenase Activity

Parrish¹,

Leopold²

1978

Plant Physiol.

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“…Stimulation is not attributable to the inhibition of catalase (by CN, for example) both because antimycin may cause stimulation, and because the RQ remains close to 1. The stimulation of fruit and tuber respiration by ethylene is attended by a sharp increase in glycolysis (27)(28)(29).…”

Section: Discussionmentioning

confidence: 99%

“…First, whereas tuber and aged slice respiration entails carbohydrate metabolism by way of glycolysis, the pentose-P pathway and the TCAC,3 fresh slices utilize fatty acids as substrate and show little or no TCAC activity (18). Second, slice respiration becomes CNinsensitive with aging (10), and tuber respiration in response to CN progresses from resistant to stimulated (11,29). By contrast, fresh slice respiration is predominantly CN-sensitive (10).…”

mentioning

confidence: 99%

Relative Contribution of Cytochrome-mediated and Cyanide-resistant Electron Transport in Fresh and Aged Potato Slices

Theologis¹,

Laties²

1978

Plant Physiol.

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135

101

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The respiration of fresh potato ( Solanum tuberosum, var. Russet Burbank) slices is predominantly cyanide-sensitive whether in the presence or absence of uncoupler. By contrast, the wound-induced respiration which develops in thin slices with aging is cyanide-resistant, and in the presence of cyanide, sensitive to chlorobenzhydroxamic acid, a selective inhibitor of the cyanide-resistant respiration. Titration of the alternate path in coupled slices with chlorobenzhydroxamic acid, in the presence and absence of cyanide, shows that the contribution of the cyanide-resistant pathway to the wound-induced respiration is zero. Similar titrations with uncoupled slices reveal that the alternate path is engaged and utilized extensively.The maximal capacity of the cytochrome path (V,yt) has been estimated in fresh and aged slices in the presence of the uncoupler carbonyl-cyanide m-chlorophenyl hydrazone. It has been found that V,yt of aged slices is but 30 to 40% higher than that of fresh slices. The results suggest that the bulk of the wound-induced respiration is mediated through the cytochrome pathway which exists in fresh slices in suppressed form, and which is fully expressed by slice aging. The engagement of the alternate path by uncouplers in aged slices is attributed to an increase in substrate moblization, with the result that the electron transport capacity of the cytochrome chain is exceeded.The respiration rate of thin potato slices immediately following cutting is four to five times that of the intact tuber. In the subsequent 24 hr the respiration rises another 4-to 5-fold to yield the wound-induced respiration. Thus, the respiration of aged slices may be 25 times that of the intact tuber (18,32). Slice aging in potato is characterized by two main metabolic transitions. First, whereas tuber and aged slice respiration entails carbohydrate metabolism by way of glycolysis, the pentose-P pathway and the TCAC,3 fresh slices utilize fatty acids as substrate and show little or no TCAC activity (18). Second, slice respiration becomes CNinsensitive with aging (10), and tuber respiration in response to CN progresses from resistant to stimulated (11,29). By contrast, fresh slice respiration is predominantly CN-sensitive (10).Attempts to correlate the respiratory rise which accompanies slice aging with an increase in specific glycolytic or respiratory enzyme activities have not been successful (16,33). On the other hand, it has been shown that the control of phospholipid biosynthesis determines the development of the wound-induced respiration (33, 34). These observations implicate membrane biosyn-

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“…De acordo com Illeperuma et al (1998), o incremento no conteúdo de açúcar em tubérculos de batatas é também causado por outros fatores além do frio, tais como a idade (Burton, 1982;Isherwood, 1976); o etileno e tratamentos com HCN (Solomos & Laties, 1975) e uma variedade de práticas culturais (Sowokinos, 1990).…”

Section: Introductionunclassified

Carboidratos não estruturais em tubérculos de dois genótipos de batata armazenados em duas temperaturas

et al. 2002

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Observa-se, em tubérculos de batata submetidos a baixas temperaturas, aumentos nos teores de açúcares redutores, os quais, no momento da fritura, provocam o escurecimento do produto, inviabilizando-o comercialmente. Avaliou-se a concentração de carboidratos em duas cultivares de batata (Pérola e Atlantic), armazenados em duas condições de temperatura. Os tubérculos foram produzidos nos cultivos de outono e primavera de 1999. Logo após a colheita, os tubérculos foram divididos em dois lotes, padronizados quanto ao tamanho, armazenados durante 40 dias, em condições de ambiente (21±3ºC para a produção de outono; 24±2ºC para a produção de primavera) e sob refrigeração (2±1ºC). Em intervalos regulares de dez dias, iniciando-se na data de armazenamento dos tubérculos (tempo zero), coletaram-se amostras de duas regiões dos tubérculos (central e periférica), para a determinação dos teores de amido, sacarose, carboidratos solúveis totais e açúcares redutores. Os teores de amido não foram alterados pelas condições de armazenamento, enquanto que os demais carboidratos apresentaram elevação quando os tubérculos foram submetidos à refrigeração, principalmente entre 10 e 20 dias de armazenamento. Contudo, as variações em respostas à baixa temperatura apresentaram-se diferenciadas em função do genótipo, da época de cultivo das plantas e das regiões dos tubérculos.

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The Mechanism of Ethylene and Cyanide Action in Triggering the Rise in Respiration in Potato Tubers

Cited by 96 publications

References 23 publications

Confounding of Alternate Respiration by Lipoxygenase Activity

Confounding of Alternate Respiration by Lipoxygenase Activity

Relative Contribution of Cytochrome-mediated and Cyanide-resistant Electron Transport in Fresh and Aged Potato Slices

Carboidratos não estruturais em tubérculos de dois genótipos de batata armazenados em duas temperaturas

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