A Comparative Study of CN-Resistant Respiration in Different Cultures of Tobacco Callus

The callus of Nicotiana rustica cv Gansu yellow flower and N. tabacum cv willow leaf were cultured on ordinary subculture medium (M-1) and on regeneration medium (M-2), respectively. No differentiation was observed in Gansu yellow flower tobacco callus cultures grown on both M-1 and M-2 medium. The respiration of both cultures was partially resistant to cyanide and markedly inhibited by m-chlorobenzhydroxamic acid. The relative contributions of alternative and cytochrome pathway were 31% and 47% of the total respiration, respectively, in M-1 callus cultures. The relative O₂ uptake of the two pathways was not changed significantly in M-2 callus cultures. In subcultured M-1 callus cultures of Willow leaf tobacco, the respiration mediated via alternative pathway was about 29 to 38% of the total respiration, and the cytochrome pathway still was the major respiratory pathway. In M-2 callus cultures in which differentiation occurred, the relative contribution of alternative pathway increased to 41 to 47% of the total respiration, and the cytochrome pathway decreased considerably. These results suggested that the change of respiratory electron transport pathway was probably related to the differentiation of tobacco callus cultures.     

甘肃黄花烟草愈伤组织抗氰呼吸的研究

根据呼吸抑制剂试验和氧肟酸滴定法测定结果表明,甘肃黄花烟草愈伤组织呼吸中有明显的抗氰交替途径运行,平均占总呼吸的31%;但仍以细胞色素途径为主,平均占总呼吸的46%;还有23%不受 KCN 加 m-CLAM 抑制的未知剩余呼吸。改变培养基的激素成分和浓度,在不引起愈伤组织发生明显分化条件下,愈伤组织的生长和呼吸速率虽有不同,但抗氰交替途径和细胞色素途径对总呼吸的相对贡献程度和二者的变化趋势基本一致。     

Studies on the CN-resistant Respiration in Callus of Nicotiana rustica,Gansu Yellow Flower

In attempting to examine whether CN-resistant respiratory pathway is present in callus culture, we used tobacco callus cultures grown on different media. The M-1 medium contained tbe mineral and organic elements of MS medium and was supple,nented with 6-BA (0.5 mg/l) and 2,4-D (2 mg/l), and M-2 medium with 6-BA (2mg/l) and IAi (1 mg/l). No differentiation was observed in both of them. The respiration of M-1 callus was partly resistant to CN, and was markedly inhlbited by m-CLAM in the presence or absence of CN. Experiments of m-CLAM titration showed that the averages of relative contribution of alternative and cytochrome pathway in M-1 callus were 31% awl 46%of the total respiration respectively during the euliure period of 25 days. A same experiment was made on the M-2 callus. It was found that the pereeutages of relative contributions of the two electron transport pathways to the total respiration were approximately the same as those of the M-1 callus, although the respiratory rate was higher in M-2 callus. The above results showed that the bulk of respiratory electron flux was mediated by the eytoehrome pathway, although the alternative pathway was operative in callus of tobacco. The change of exogenous hormones added in the medium could not produee significant effects on the degree of relative contribution of two electron transport pathways under non-differentiation conditions.     

Influence of osmotic stress on the respiration of potato tuber callus

Potato tuber ( Solanum tuberosum L. cv. Bintje) callus shows a decrease in fresh weight and an increase in dry weight upon transfer to nutrient medium supplemented with 0.3 or 0.5 M mannitol. The osmolarity of the intracellular fluid increases simultaneously. Probably mannitol is taken up from the medium till the osmolarity of the tissue is in equilibrium with that of the medium. After osmotic adaptation, on a medium with 0.5 M mannitol, growth is negligible, although the tissue retains its viability.
Respiration increases upon transfer to medium with extra mannitol, especially when expressed on a fresh weight basis. On this basis cytochrome and alternative pathway capacities do not change appreciably. The respiratory increase is exclusively caused by an increased engagement of the alternative pathway. The participation of this pathway in uninhibited respiration increases from about 10 to 90% upon transfer to medium with extra mannitol. The increase in respiration is partly correlated with the decrease in fresh weight upon transfer. Per disc, the capacities of the cytochrome and alternative pathway decline. Yet, total respiration per disc significantly increases due to the increased participation of the alternative pathway. This results in an almost equal ATP-production per disc before and after transfer. We suggest, that the alternative pathway functions as a reserve capacity in potato callus, which is switched on when ATP-production coupled to the cytochrome pathway is impaired.     

Changes in Respiratory Metabolism during Callus Growth and Adventitious Root Formation in Jerusalem Artichoke Tuber Tissues

The CN-resistant alternative oxidase pathway was examined inrelation to the formation of callus and adventitious roots ofJerusalem artichoke tuber tissues. During the early stage ofincubation at 28?C, respiration was significantly activatedand the O₂-uptake rate via the Cyt pathway increased 2.5–2.6times by the second day of culture regardless of the presenceof 2,4-D. However, further increases and preservation of highlevels of Cyt pathway activities were observed only in the callusformingtissues. The capacity of the alternative pathway also increased,but the actually operating fraction was very small (0–4%of total respiration). On the other hand, during the later stagesof culture in which adventitious roots emerged from the callus,activation of the alternative pathway was observed. These resultssuggested that the alternative pathway was not involved in callusgrowth but was related to root formation in callus tissues ofJerusalem artichoke tubers. (Received October 29, 1986; Accepted April 20, 1987)     

Effects of KCN and NaN3 Pretreatment on the Cyanide-Resistant Respiration in Tobacco Callus

The effects of KCN (0.5mmol/L) and NaN3 (0.01 mmol/L) pretreatment on the operation of the alternative pathway in subcultured tobacco (Nicotiana rustica L. cv. Gansu yellow flower) callus were analyzed. After treatment with KCN and NaN3 for 12 h, the total respiration rate (Vt) decreased by 12% and 17%, whereas oxygen consuption by the cytochrome pathway decreased by 22% and 28% respectively. The capacity of the alternative pathway (Valt) remained constant, while the activity of the alternative pathway (ρ· Valt ) inreased slightly. This changing pattern led to a declined contribution of the cytochrome pathway to the total respiration rate and an increased activity of the alternative pathway. Treatment with KCN for 24 h brought about a slight rise of oxygen consumption by the cytochrome pathway as compared with that in callus treated for 12 h, but the oxygen consumption was still lower than that in the untreated callus. Treatment with NaN3 for 24 h resulted in a profound decrease of the cytochrome pathway operation and a continuing increase of the alternative pathway operation. These data indicated that the enhanced operation of the alternative pathway played a compensatory role to the total respiration when the cytochrome pathway was partially inhibited in tobacco callus.     

Possible Participation of Active Oxygen Species in the Induction of Cyanide-Resistant Pathway at the Initial Senescence of Tobacco Callus

Changes in active oxygen species (AOS) and respiration, with special reference to the alternative pathway of respiration, were followed in callus of tobacco (Nicotiana rusticaL.) during its growth and senescence. Two peaks of the total respiration rate were observed: the first one appeared on day 11, and the second one on day 19 (in senescing callus). H₂O₂and O^– ₂contents increased gradually and reached the greatest values when callus senescence initiated (by day 11 and day 15, respectively), and then declined. The peaks of H₂O₂and O^– ₂before the onset of senescence coincided with the peaks of capacity V _altand activity V _altof alternative pathway, respectively. After the onset of senescence, ·OH accumulated abundantly and maintained at a relatively high level from then on, accompanied by the decrease in both V _altand V _alt. The conclusion is that these three active oxygen species operated coordinately to regulate the alternative pathway during growth and senescence of tobacco callus, as confirmed by the callus treatments with AOS scavengers, exogenous ·OH, and inhibitors of antioxidant enzymes. The possibility of AOS-induced alternative pathway respiration at the initial senescence of tobacco callus is discussed.     

The Cyanide-resistant Respiration in Callus of Nicotiana rustica cv. Gansu Yellow Flower Under Low Temperature

The increasement of the operation (ρValt) and the capacity of the alternative pathway (Valt) in tobacco (Nicotiana rustica L. cv. Gansu Yellow Flower) callus that treated by low temperature (4 ℃) were observed. The two electron transport pathways were changed alternatively, the cyanide-resistant respiration was the main respiratory pathway from the 2nd day to the 5th day, while the cytochrome pathway was the main pathway consistently in control callus. Cycloheximide and chloramphenicol treatment which inhibited protein synthesis resulted in dramatic and partly inhibition of Valt induced by low temperature respectively. This further proved above result that low temperature induced Valt. The same result was found when two inhibitors were used together. The analysis of heat production of callus indicated that the operation of the alternative pathway could be regulated to improve the micro-environmental temperature of tobacco callus to adapt to low temperature. The possible participation of the alternative pathway in the response to low temperature and its physiological roles were discussed.     

烟草愈伤组织继代培养期间呼吸途径与活性氧水平动态变化

继代培养期间的烟草愈伤组织总呼吸速率分别在第11天和第19天出现两次跃升,同时抗氰呼吸的发生与运行逐渐加强,在两呼吸高峰之间达到极大值,随后则逐渐下降,但愈伤组织的电子传递仍以细胞色素途径为主．通过对愈伤组织衰老过程中活性氧代谢变化分析,发现抗氰呼吸发生与H     

Alternative pathway respiration in vivo of potato tuber callus grown at various temperatures

During incubation of potato tuber discs ( Solanum tuberosum L. cv. Bintje) on a callus-inducing medium at 28°C, a high capacity of in vivo alternative pathway respiration develops (75% of uninhibited respiration is azide-resistant). When callus induction takes place at 8°C, only 45% of respiration is resistant to azide. In the lag phase of growth the activity of alternative pathway is low. during the exponential growth phase the activity reaches its maximal rate. This in vivo activity is of the same size at both culture temperatures. As a consequence a greater part of alternative pathway capacity is operating in uninhibited respiration during growth at low temperatures.     

能量对香石竹切花在瓶插期间呼吸电子途径的影响

采用外加0.1 mmol/L ATP或0.5 mmol/L二硝基苯酚(DNP)的方法,研究了香石竹(Dianthus caryophyllus L.)切花在25±1℃和80%～90%相对湿度下瓶插期间呼吸电子传递途径的变化情况.结果表明,香石竹切花在瓶插7 d时的呼吸速率达到高峰;ATP处理明显加快切花的呼吸速率,在瓶插7 d时呼吸速率高峰值较对照(未用ATP处理)升高1倍.细胞色素途径与总呼吸活性存在显著正相关.细胞色素途径占总呼吸的比重在切花瓶插4 d后上升,并且线粒体电子传递主要依靠细胞色素主路途径进行.经ATP处理后香石竹切花的交替呼吸途径的容量、实际运行活性和运行系数明显增加;交替呼吸途径占总呼吸活性比重在瓶插4 d后迅速上升,并且交替呼吸途径容量与总呼吸活性存在显著正相关.而DNP处理则降低交替呼吸途径容量.这说明外源ATP处理加强了香石竹切花在整个瓶插期间的呼吸作用,增加了呼吸速率的高峰值,提高了抗氰呼吸作用.     

Regulation of the activity of the alternative oxidase in callus forming discs from potato tubers

Callus-forming discs from potato tubers lose 80% of their starch during one month of incubation on nutrient medium containing either 0, 3 or 6% (w/v) sucrose. The content of soluble sugar in the discs varies from 5 mg (incubated without sucrose) to 22 mg (on 3% sucrose) and 40 mg (on 6% sucrose) per g fresh weight. The activity of the cytochrome pathway (V_cyt) increases during the first week of incubation on all media. Thereafter V_cyt decreases again on 0% sucrose medium, while it remains constant on 3 and 6% sucrose media. Alternative pathway capacity (V_alt), absent in freshly sliced tissue, shows a sharp increase during the first days of incubation, independent of the sucrose concentration in the medium. This capacity further increases during prolonged incubation on 3 and 6% sucrose but decreases on 0% sucrose. The in vivo activity of the alternative pathway (the participation in uninhibited respiration, ?V_alt) varies with the sucrose concentration and with the culture time. In tissue incubated for 2-3 weeks on 6% sucrose as much as 45% of the electrons are transfered to oxygen via the alternative pathway. In this tissue the factor Q (the part of the alternative pathway capacity that is operative) is about 0.8, while in tissue incubated on 0 and 3% sucrose media p generally does not exceed 0.5. When chloramphenicol, an inhibitor of mitochondrial protein synthesis, is added to the medium together with 3% sucrose, the increase in V_yet does not occur, while the induction of V_alt during the first week of incubation is the same as without chloramphenicol. A greater part of the alternative pathway capacity becomes operative in this tissue, leading to values of Q of almost 1 after prolonged incubation. Apparently, incubation on high sugar medium leads to extra participation in respiration of the energetically inefficient alternative oxidase pathway Excess sugar leads to wasteful respiration suggesting that the alternative oxidase functions as an ‘energy overflow’.     

The regulation of respiration and growth of potato tuber callus by endogenous ethylene. Suppression of ethylene action by 2,5-norbornadiene

The growth (fresh and dry weight increase) of potato tuber ( Solanum tuberosum L. cv. Bintje) callus discs was stimulated by incubation in air with 500 ppm 2,5-norbornadiene (NBD, a competitive inhibitor of ethylene action) and inhibited by incubation in air with 4 000 ppm NBD. Ethylene formation by the callus was stimulated by NBD. The development of the alternative pathway, measured in isolated mitochondria was inhibited by NBD in a concentration-dependent way. The alternative pathway capacity, measured in vivo, was inhibited by 4 000 ppm NBD, but not by 500 ppm. Uninhibited in vivo respiration, which consists of cytochrome path activity and alternative path activity, was stimulated by the treatment with 500 ppm NBD. The main contribution to this stimulation was made by the cytochrome pathway. In 4 000 ppm NBD-treated callus, uninhibited respiration seemed to be unaffected as a consequence of an inhibited cytochrome path activity, which was compensated by a stimulated alternative path activity. Both in 500 and 4 OIK) ppm NBD-treated callus the alternative path activity in vivo was stimulated.
The regulatory role for endogenous ethylene in potato tuber callus is discussed in relation to: 1) The induction of respiratory pathways, 2) the supply of reduction equivalents in vivo and 3) growth.     

短日照对休眠诱导期油桃花芽两条电子传递途径的调控

以油桃品种“曙光”为试材,采用呼吸抑制剂法研究了短日照处理下花芽在休眠诱导期两条电子传递途径的发生和运行情况.结果表明:花芽总呼吸速率(Vt)和细胞色素电子传递途径呼吸速率(ρ'Vcyt)均呈双峰曲线变化,短日照可同步诱导两者的一次峰前移、二次峰后延,抑制ρ’Vcyt,但对Vt无显著影响.交替途径容量(Valt)和实际运行活性(ρValt)亦呈双峰曲线,两者基本同步变化,短日照可以显著诱导Valt和ρValt的前期高峰期提前,提高Valt和ρValt,对后期高峰期无明显作用.细胞色素电子传递途径呼吸速率下降和交替途径呼吸速率上升是油桃花芽休眠诱导期的重要特点.从两条电子传递途径的呼吸速率对总呼吸速率的贡献率来看,细胞色素电子传递途径仍是主要电子传递途径,交替途径起辅助与分流作用.     

The relationship between phosphate status and cyanide-resistant respiration in bean roots

Bean ( Phaseolus vulgaris L.) seedlings were cultured on complete or phosphate-deficient nutrient medium. After 14 days of culture on phosphate-deficient medium the visible symptoms of P_i deficiency were observed only in the shoot, the fresh and dry weights of the roots were slightly higher than in control plants. The decreased P_i content in the roots had little effect on total respiration rate but had an effect on the level of inhibition of respiration by cyanide. The high resistance of respiration to cyanide observed in P_i-deficient roots was the result of the suppression of cytochrome path activity and an increased participation of the alternative, cyanide-resistant pathway. The cytochrome pathway activity increased when inorganic phosphate was supplied to P_i-deficient roots for 1 or 3.5 h. It is speculated that the suppression of cytochrome pathway in P_i-deficient roots may result from restriction of the phosphorylating capacity or a partial inhibition of cytochrome oxidase activity.     

盾叶薯蓣胚乳再生体系的建立及其染色体倍性鉴定

以盾叶薯蓣（Dioscorea zingiberensis）的胚乳为外植体,研究了不同植物生长调节剂对胚乳愈伤组织诱导及植株再生的影响,并鉴定了再生植株。结果表明：愈伤组织诱导形成的适宜培养基为MS＋2.0mg·L^–12,4-D＋0.5mg·L^–16-BA,不定芽分化的适宜培养基为MS＋2.0mg·L^–16-BA＋0.1mg·L^–1NAA,生根的适宜培养基为1/2MS＋0.3mg·L^–1NAA;再生植株炼苗移栽后,成活率可达80%;对获得的再生植株腋芽生长点进行染色体制片观察,发现染色体数目为20的细胞占观察细胞总数的10%,染色体数目为21–29的细胞占16%,染色体数为30的细胞占74%;获得了三倍体植株。     

LIGHT RESPIRATION IN SIX ESTUARINE PHYTOPLANKTON SPECIES: CONTRASTS UNDER PHOTOAUTOTROPHIC AND MIXOTROPHIC GROWTH CONDITIONS1

The photoresponse of respiration was examined in six estuarine phytoplankton species grown at a limiting irradiance in the presence or absence of glucose. Cellular respiration rates in the dark, at the growth irradiance, and at saturating light levels were higher in glucose-grown cultures than in photoautotrophic cultures. Glucose uptake also affected the relationship between incident irradiance and gross respiration rate, and the specific respiratory pathways that contributed to the respiration versus irradiance (R vs. I) response. The energy-conseming Mehler reaction contributed largely to light-stimulated respiration in photoautotrophic (energy-limited) cultures. However, the energy-dissipating alternative pathway was the predominant form of respiration measured in mixotrophic (energy-sufficient) cultures. Based on these and previous observations, a model of phytoplankton R us. I response is presented, in which the relative contributions of different light respiratory processes (cytochrome pathway respiration, alternative pathway respiration, chlororespiration, Mehler reaction) are dependent on the incident irradiance and cellular energy content.     

成熟和褐变荔枝果实呼吸作用和脂氧合酶活性

荔枝果实完全成熟和果皮变鮮红时,呼吸速率降低,仅相当于果皮带绿时的39.4％。此时果皮和果肉的脂氧合酶活性亦明显降低,分别相当于后者的60.2％和49.1％。成熟荔枝果实果皮呼吸作用对KCN抑制敏感。2mM KCN抑制果皮总呼吸的91.8％,而仅抑制果肉的56.9％。荔枝果皮呼吸的电了传递主要是通过细胞色素氧化酶途径,而果肉則可能一半是通过其它氧化酶途径。2mKCN和1.5mM SHAM抑制成熟果皮总呼吸97.9％,为SHAM抑制的交替途径呼吸占总呼吸5.28％。相同浓度KCN和SHAM抑制褐变果皮总呼吸79.7％,则SHAM抑制的交替途径呼吸占27.1％。果实褐变时,果成交替途径呼吸比例增高。这一变化可能促进H_2O_2积累、乙烯产生和果皮褐变深化。     

Cyanide-Resistant Respiration in Relation to Fruit Respiratory Climacteric

Changes in respiratory rate and the effects of respiratory inhibitorson respiration were determined in apple (Malus sylvestris cv. Delicious) and red pepper (Capsicum fructescens) fruits dusting different stages of development and ripening.The results showed that there was an abrupt rise in respiration daring ripening inapple fruit, but the respiration of the red pepper declined continuously throughout theripening period. Thus the apple is climacteric and the red pepper is non-climacteric fruit. The respiration of apple fruit was sensitive to KCN (1 mM) during the period ofdevelopment but changed to CLAM-sensitive and CN-resistant during preclimactericand climacteric phases, indicating that a diversion of respiratory pathways from the cy-tochrome path to the alternative path has occurred. The respiration of the red pepperfruit was CN-sensitive thoughout the whole period of fruit ripening, suggesting thatthe operation of the CN-resistant path was insignificant. Slices from climacteric apple fruits developed induced .respiration after aging, bothKCN and CLAM (1 mM) inhibited the induced respiratic considerably. However, slices from red pepper fruits showed no evidence of induced respiration after aging. Slices from climacteric apple fruits infiltrated with 3 mM CLAM before aging, reducedthe peak of the induced respiration by about 30%, indicating that the development ofinduced respiration was suppressed by the presence of CLAM. The above results indicated that the: climacteric fruits were characterized by diversion of traffic from the cytochrome path to the alternative path during ripening andby the development of induced respiration after slicing and aging. While in nonclimacteric fruits no .diversion of electron transport path was observed during ripening andno induced respiration occurred after aging. Although both the eytochrome and alternative pathways were present in the tissue of red pepper fruits, the alternative pathwas not operating except when the cytochrome path was blocked or was saturated by electron flow.     

Growth, photosynthesis and respiration in Plantago coronopus as affected by salinity

Plantago coronopus was grown in a non-saline culture solution and in a culture solution containing 50 m M NaCl. The rates of dry matter accumulation in both roots and shoots were not affected by 50 m M NaCl. Photosynthesis, expressed per shoot, was also the same in both environments. Neither the rate of shoot respiration nor that of root respiration was affected by salinity. In both environments the alternative respiratory pathway contributed to the same extent in root respiration. The activity of the alternative pathway decreased with increasing age. Since the respiratory activities were the same in plants grown under both saline and non-saline conditions and since the alternative respiratory pathway was also equally active in roots under both environmental conditions, it is concluded that respiratory costs involved in growth in 50 m M NaCl are negligible in terms of the plant's total energy costings.