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1.
Control of the germination of secondary dormant cocklebur seeds by various germination stimulants 总被引:2,自引:0,他引:2
Esashi Yohji; Okazaki Makiko; Yanai Nobuaki; Hishinuma Kohya 《Plant & cell physiology》1978,19(8):1497-1506
The responsiveness of non-dormant, upper cocklebur (Xanthiumpennsylvanicum Wallr.) seeds to various germination stimulants,such as CO2 C2H4 CS(NH2)2, BA and enriched O2, decreased withincreasing periods of water imbibition and was completely lostin the state of secondary dormancy. Unlike CO2 BA and CS(NH2)2however, C2H2 and enriched O2 effectively prevented the developmentof secondary dormancy, and their combination was the most effectivefor stimulating the germination of seeds which had undergoneimbibition for a long time. CS(NH2)2 and BA were effective,not by themselves but either under anaerobiosis or elevatedO2 tension. Growth of the axial and cotyledonary segments excisedfrom aged seeds remained responsive to these germination stimulantsand could be further stimulated by exogenous C2H2. With imbibitionat a lower temperature, the seeds maintained high germinationin response to various stimulants and a high rate of C2H2 andCO2 production during a long period of water imbibition. Theseresults are discussed in terms of the two possible causes forthe loss of responsiveness or induction of the secondary dormancy. (Received June 27, 1978; ) 相似文献
2.
High O2 tensions, CO4, C2H4 and high temperatures were effectivenot only in breaking the dormancy of cocklebur (Xanthium pennsylvanicumWallr.) seeds but also in increasing the germination potentialof the nondormant but small seeds. There were few qualitativedifferences in response to these factors between the dormantand impotent seeds. Unlike CO2, however, enriched O2 and C2H4were stimulative even at the low temperature of 13°C. Germination induced by CO2, C2H4 and high temperature treatmentswas lowered when endogenously evolved C2H4 or CO2 was removed,whereas the effect of O2 enrichment was not affected by theirremoval. CO2 and high temperatures remarkably stimulated C2H4production, whereas O2 enrichment had no such effect. C2H4 productivity was lower in the dormant than non-dormantseeds, suggesting that the after-ripening is characterized byincreasing C2H4 production. (Received August 20, 1974; ) 相似文献
3.
Esashi Yohji; Fuwa Noritoshi; Kurota Akiko; Oota Hiroshi; Abe Michikazu 《Plant & cell physiology》1987,28(1):141-150
Effects of C2H4 and CO2 on respiration of pre-soaked upper cocklebur(Xanthium pennsylvanicum Wallr.) seeds during a pre-germinationperiod were examined in relation to effects of the two gaseson germination. At 33?C, cocklebur seed germination was greatlystimulated. This high temperature-stimulated germination wasseverely inhibited by C2H4, but not by CO2, although both gasesstimulated germination at 23?C. C2H4 promoted seed respirationat 23?C, but its promotive effect decreases with increasingtemperature and disappeared at about 35?C, while CO2 stimulatedrespiration regardless of temperature. CO2 augmented the operationof the CN-sensitive, cytochrome path (CP) regardless of temperature,resulting in an increase in the ratio of the CP flux to a CN-resistant,alternative path (AP) flux. On the other hand, C2H4 augmentedthe operation of both paths, particularly of the AP, at 23?C,where it promoted germination. However, at 33?C where germinationis suppressed by C2H4, C2H4 preferentially stimulated respirationvia the AP, thus leading to an extremely high ratio of AP toCP. The inhibitory effect of C2H4 on germination at 33?C disappearedcompletely in enriched O2, under which conditions CP is knownto be augmented. At 23?C, CO2 and C2H4 acted independently incontrolling seed respiration, but they were antagonistic at33?C. The independent action appeared when the AP flux was verylow relative to the CP flux, while the antagonism appeared whenthe AP flux had risen. This differential action of the two gasesat different temperatures was also observed in the ATP level,adenylate pool size and energy charge of the axial tissues.These results suggest that the germination-controlling actionsof both CO2 and C2H4 are fundamentally manifested through themodification of respiratory systems. However, the germination-inhibitingeffect of C2H4 at 33 ?C was not removed by inhibitors of AP,and there was little difference in the adenylate compounds betweenthe C2H4-treated and non-treated seeds at 33?C. Therefore, thephysiological action of C2H4 can not be explained only in termsof regulation of the respiratory system. (Received January 24, 1986; Accepted November 17, 1986) 相似文献
4.
Esashi, Y., Hase, S. and Kojima, K. 1987. Light actions in thegermination of cocklebur seeds. V. Effects of ethylene, carbondioxide and oxygen on germination in relation to light.J.exp. Bot. 38: 702710. Effects of ethylene, CO2 and O2 on the germination of after-ripenedupper cocklebur (Xanthium pennsylvanicum Wallr.) seeds wereexamined in relation to pre-irradiation by red (R) or far-red(FR) light In order to remove the pre-existing Pfr, seeds weresoaked in the dark for various periods prior to light irradiationand gas treatments. Regardless of light, 0.3 Pa C2H4 promotedgermination at 23 ?C, but it strongly inhibited germinationwhen applied at 33 ?C, the optimal temperature for the germinationof this seed. However, delayed application of C2H4 during 33?C incubation stimulated germination independently of lightin a similar manner to that seen at 23 ?C. It is, therefore,suggested that the germination-regulating action of C2H4 iscompletely independent of phytochrome. In contrast, the germination-promoting effect of 30 kPaCO2 was pronounced only when the seeds were previously irradiatedby R, regardless of temperature, suggesting that CO2 actionto promote germination depends upon Pfr. A synergism betweenCO2 and C2H4 at 23 ?C was observed only in the germination ofseeds pre-irradiated by R, while at 33 ?C an antagonism occurredindependently of light. The stimulation of C2H4 production byCO2 was most striking in the cotyledonary tissue pre-irradiatedby R. However, the R-dependent enhancement of CO2-stimulatedC2H4 production was negated by the subsequent FR and it wasnot found in the presence of 1-aminocyclopropane-1-carboxylicacid (ACC). Moreover, the R dependency of the germination-promotingCO2 effect disappeared in the presence of C2H4. The R-dependentC2H4 production enhanced by CO2 may thus be involved, at leastpartially, in some step of conversion from methionine to ACC. The germination-promoting effect of C2H4, but not CO2, was enhancedby O2 enrichment regardless of light. However, the germination-promotingeffect of pure O2 itself appeared to depend upon pre-irradiationwith R Key words: Carbon dioxide, cocklebur seed, ethylene, far-red light, germination, oxygen, red light, Xanthium pennsyloanicum 相似文献
5.
Non-dormant small cocklebur seeds (Xanthium pennsylvanicum Wallr.)are potentiated to germinate, if they are subjected to anaerobiccondition for certain time periods after being sufficientlypre-soaked under aerobic conditions. This is termed "anaerobicinduction" of seed germination. Such induction was slightlyinhibited by CO2 applied during anaerobiosis, but markedly promotedby C2H4 Thus, C2H4 can exert its action even in anaerobiosis,but does not enhance the fermentative CO2 evolution. No actualanaerobic induction occurred when over 1? O2 was present, evenif C2H4 had been applied. Therefore, anaerobic induction seemsto be due to a concerted action of some anaerobically proceedingevents and the anaerobically produced C2H4. (Received May 31, 1976; ) 相似文献
6.
The axial growth of de-coated cocklebur (Xanthium pennsylvanicumWallr.) seeds, whose axes were divided into 4 zones, was examinedin relation to the temperature-dependent shift of the effectof C2H4 on germination. At 23?C, where both C2H4 and CO2 stimulatedgermination, CO2 promoted the axial growth at the radicle tipzone, whereas C2H4 promoted growth in the proximal portion ofthe axis. At 33?C, C2H4 inhibited germination, and stronglysuppressed the growth at the radicle tip, whereas the effectof CO2 did not change. The inhibition of growth at the radicletip zone was alleviated by O2 enrichment, which also reversedthe inhibition of germination. It is thus apparent that thetemperature-dependent shift of the action of C2H4 is associatedwith a temperature-dependent responsiveness of the radicle tipzone to C2H4. Growth of the radicle tip zone was sensitive toNaN3, whereas the proximal portion was sensitive to benzohydroxamicacid, an inhibitor of alternative respiration, suggesting thatthere may be an increase in the operation of the alternativerespiration path along a gradient of axial tissue from the tiptowards the cotyledonary side. The effects of CO2 and C2H4 arediscussed in relation to the different respiratory activitiesin each axial zone of cocklebur seeds. (Received May 9, 1986; Accepted November 6, 1986) 相似文献
7.
GORECKI RYSZARD J; ASHINO HIROKI; SATOH SHIGERU; ESASHI YOHJI 《Journal of experimental botany》1991,42(3):407-414
Relationships between seed vigour and ethylene (C2H4) productionwere studied using C2H4-responsive fatty cocklebur seeds (Xanthiumpennsyhanicum Wallr.) and C2H4-insensitive starchy pea seeds(Pisum sativum L. cv. Alaska), which had been harvested in differentyears and subjected to different storage conditions. In bothspecies, the seeds with the highest vigour evolved the largestamounts of C2H4 during a period of water imbibition. The reductionof C2H4 production in cocklebur seeds occurred concomitantlywith the reduction in the growth potentials of both axial andcotyledonary tissues. Similarly, the activity of ACC-C2H4 conversionincreased with soaking, and was greater in seeds of high vigourcompared with those of low vigour. However, the change in ACCcontent in pea seeds differed from that in cocklebur seeds.That is, pea seeds with high vigour accumulated less ACC duringan imbibition period than those with low vigour. From theseresults it was suggested that the inferior C2H4 production bylow vigour pea seeds is mainly attributable to low ACC-C2H4conversion, whereas that by low vigour cocklebur seeds is dueto the shortage of ACC supply in addition to the reduced ACC-C2H4conversion. However, germination of deteriorated cocklebur seedswas not restored by exposure to ACC or C2H4, suggesting thatthe loss of seed vigour reduces the responsiveness of seedsto C2H4 as well as C2H4 production. Key words: Pea, cocklebur, seed vigour, ethylene production, 1-aminocyclopropane-1-carboxylic acid 相似文献
8.
Contrasted Effects of CO2 on the Regulation of Dormancy and Germination in Xanthium pennsylvanicum and Setaria faberi Seeds 总被引:1,自引:0,他引:1
The effects of CO2 on dormancy and germination were examinedusing seeds of cocklebur (Xanthium pennsylvanicum Wallr.) andgiant foxtail (Setaria faberi Herrm.). The rate of germinationof the giant foxtail seeds as well as cocklebur was promotedby exogenously applied CO2 at a concentration of 30 mmol mol-1regardless of the sowing conditions. However, seeds which failedto germinate in the presence of CO2, entered a secondary phaseof dormancy under unfavourable germination conditions. If CO2was applied to seeds under conditions such as water stress imposedwith a 200 mol m-3 mannitol solution, a hypoxic atmosphere of100 mmol mol-1 O2 or a treatment of 0·1 mol m-3 ABA,development of secondary dormancy was accelerated. These contrastedeffects of CO2 were observed in ecological studies. Under naturalfield conditions germination of buried giant foxtail seeds respondedpositively to CO2 during a period of release from primary dormancyfrom Feb. to May, but CO2 accelerated secondary dormancy commencingin early Jun. In other words, in the presence of CO2, both theenvironmental conditions and the germination states of the seedsclearly showed secondary dormancy-inducing effects. Thus, itseems that CO2 has contrasted effects on regulation of dormancyand germination of seeds depending on the germination conditions.Copyright1995, 1999 Academic Press Xanthium pennsylvanicum, cocklebur, Setaria faberi, giant foxtail, CO2, water stress, hypoxia, ABA, germination, secondary dormancy 相似文献
9.
Etiolated Avena sativa L. coleoptile sections were used to determinethe influence of C2H4 on in vivo and in vitro rates of CO2 fixation,and to measure the influence of various permutations of C2H4,CO2, and malate on growth. Whereas 1 mM malate or 320 µI-1 CO2 stimulated growth by approximately 100 per cent, inhibitionof growth by 10-8 µ I-1 C2H4 was substantial only in thepresence of malate or CO2 The increase in growth rate in responseto these two agents was eliminated by the simultaneous applicationof C2H4. The in vivo rate of dark [14C]bicarbonate fixationand in vitro enzymic assays of fixation were not measurablyinhibited by C2H4. These results are discussed in the lightof evidence which indicates that CO2-stimulated growth is mediatedby dark fixation. The data do not support the view that C2H4inhibition of growth results from an inhibition of fixation,but suggests that C2H4 may inhibit some step in the processby which malate stimulates growth. 相似文献
10.
Hasegawa Ryo; Maruyama Akiko; Sasaki Hiroshi; Tada Tomoko; Esashi Yohji 《Journal of experimental botany》1995,46(5):551-556
A possible involvement of ß-cyanoalanine synthase(CAS: EC 4.4.1.9
[EC]
) in germination processes of seeds was demonstratedusing pre-soaked upper seeds of cocklebur (Xanthium pennsylvanicumWallr.). Pretreatment in anoxia not only with KCN but also cysteine,as the substrates for CAS, stimulated the subsequent germinationof cocklebur seeds in air. However, the effect of cysteine wasmanifested even in air when applied together with C2H4, andits effect was further enhanced in combination with KCN. Thegermination-stimulating effect of KCN was intensified by C2H4only when 02 was present. In contrast, serine, another substrateof CAS, was effective in air only when combined with C2H4 and/orKCN. The addition of cysteine greatly reduced the cyanogenicglycoside content of seeds, but increased HCN evolution. Onthe other hand, glutathione did not have any effect on cockleburseed germination, HCN evolution or bound cyanogen content, suggestingthat cysteine is not acting as a reducing reagent. It is suggestedthat CAS regulates the process of cocklebur seed germinationby the dual action of enlarging the pool of amino acids andsupplying sulphydryl bases, the latter being more determinatelyimportant. Serine is effective only via the former action, whilecysteine would act via both. Key words: Cyanide, cyanogenic glycoside, ß-cyanoalanine synthase, seed germination, Xanthium pennsylvanicum 相似文献
11.
Panicum hians and Panicum milioides were found to have characteristicsintermediate to those of C3 and C4 species with respect to CO2compensation point, percentage inhibition of photosynthesisby O2 at various O2/CO2 solubility ratios, and water use efficiency.C4 species have a higher carboxylation efficiency than eitherthe intermediate or C3 species. During photosynthesis, evenunder 2.5% O2, C4 species have a higher affinity for intercellularCO2 (Km 1.6 µM) apparently due to the initial carboxylationthrough PEP carboxylase. Under low O2 the intermediate and C3species had a similar affinity for intercellular CO2 duringphotosynthesis (Km 57 µM) consistent with carboxylationof atmospheric CO2 through RuDP carboxylase. There were considerablevariation in photosynthesis/unit leaf area at saturating CO2levels in the species examined which in part is due to differencesin RuDP carboxylase /unit leaf area. The highest rates of photosynthesis/unitleaf area under CO2-saturating conditions were with the C3 specieswhich had a correspondingly high level of RuDP carboxylase/unitleaf area. Possibilities for the greater efficiency of P. hiansand P. milioides in comparison to C3 species in utilizing lowlevels of CO2 in the presence of atmospheric O2 are discussed.
1 This research was supported by the College of Agriculturaland Life Sciences, University of Wisconsin, Madison; and theUniversity of Wisconsin Research Committee with funds from theWisconsin Alumni Research Foundation. (Received June 25, 1977; ) 相似文献
12.
In 4 cultivars of tomato (Lycopersicon esculentum Mill.), theearly detachment of fruits advanced ripening and considerablyreduced the threshold value of endogenous C2H4. This indicatesa supply from the vegetative parts of (a) labile ripening-inhibitingsubstance(s) antagonizing the action of C2H4. The endogenous level of CO2 increased shortly after the risein C2H4, and maximum levels of C2H4 and CO2 occurred almostsimultaneously. The activity of PE showed no connection with ripening, but PGactivity did not occur until the onset of ripening. However,this activity increased at considerably higher C2H4 concentrationsthan the rise in WSP, and was independent of the possible presenceof ripening inhibitor(s). Hence PG is considered not to be involvedin the primary events leading to fruit ripening. Exposure of fruits to different C2H4 concentrations in the ambientatmosphere also showed PG activity to increase only after therise in WSP had started. Other pectin degrading or synthesizingenzymes may be involved. In the non-ripening Rin mutant of cv. Rutgers, no rise occurredin C2H4, CO2, WSP, and PG activity.
1 Present address: Department of Agricultural Chemistry, Facultyof Agriculture, Kochi University, Otsu 200 Monobe, Nangoku City,Kochi Prefecture 783, Japan. (Received February 16, 1978; ) 相似文献
13.
During imbibition and germination of wheat (Triticum aestivum)in the dark over 72 h, activities of the enzymes of the ascorbate(AsA)-dependent H2O2-scavenging pathway, AsA peroxidase, monodehydroascorbate(MDAsA) reductase, dehydroascorbate (DHAsA) reductase and glutathione(GSSG) reductase as well as superoxide dismutase (SOD), catalaseand guaiacol peroxidase were determined both in whole grainsand in isolated embryos and endosperm. With the exception of DHAsA reductase, activities of the otherenzymes assayed increased in germinating seeds, especially duringradicle emergence (between 2448 h of imbibition). Theseincreases, particularly for AsA peroxidase, were much higherin the embryo than in the endosperm. Within 72 h of imbibition,activities per seed increased 116-fold for AsA peroxidase, 19-foldfor guaiacol peroxidase, 5-fold for catalase and only 1·4-foldfor SOD. In contrast to the decreases in DHAsA reductase, theother AsA recycling enzyme, MDAsA reductase, increased 5-foldwithin 72 h. The results indicate that, in wheat seeds, imbibition and germinationis associated with enhanced cellular capacity to detoxify H2O2.For this detoxification the operation of AsA peroxidase togetherwith the AsA-regenerating enzymes appears to be of particularimportance. Key words: Ascorbate peroxidase, germination, hydrogen peroxide detoxification, inhibition, wheat 相似文献
14.
Effects of chilling (5 °C) period, light and applied nitrogen(N) on germination (%), rate of germination (d to 50% of totalgermination; T50%) and seed imbibition were examined inClematisvitalba L. In the absence of chilling, light and N, germinationwas minimal (3%). When applied alone, both chilling and N increasedgermination. Chilling for 12 weeks increased germination to64%, and 2.5 mM NO-3or NH+4increased germination to 1012%.Light did not increase germination when applied alone, but didwhen applied in combination with chilling and/or N. Half theseed germinated when light was combined with 2.5 mM NO-3or NH+4.The influence of chilling, light and/or N on germination wasgreater when combined, than when either factor was applied alone.Both oxidized (NO-3) and reduced (NH+4) forms of N increasedgermination, but non-N-containing compounds did not, suggestingthe response was due to N and not ionic or osmotic effects. Without additional N, T50%decreased from 1620 d at zerochilling, to around 5 d at 8 and 12 weeks chilling. AlthoughT50%was not influenced by an increase in NO-3or NH+4from 0.5to 5.0 mM , it did increase with additional applied N thereafter.However, the magnitude of the N effect was small compared tothat of chilling. Like germination, seed imbibition increasedwith a longer chilling period, but in contrast imbibition decreasedslightly with increased applied NO-3or NH+4. It is argued thatincreased imbibition is not directly related to an increasein total germination, but that it may be related to the rateof germination. Possible mechanisms involved in the reductionin dormancy ofC. vitalba seed are discussed. Clematis vitalba L.; germination; dormancy; imbibition; rate of germination; chilling; light; nitrate; ammonium; nitrogen; phytochrome 相似文献
15.
The quantum yields of photosynthetic O2 evolution were measuredin 15 species of C4 plants belonging to three different decarboxylationtypes (NADP-ME type, NAD-ME type and PEP-CK type) and 5 speciesof C3 plants and evaluated relative to the maximum theoreticalvalue of 0.125 mol oxygen quanta-1. At 25°C and 1% CO2,the quantum yield in C4 plants averaged 0.079 (differences betweensubgroups not significant) which was significantly lower thanthe quantum yield in C3 plants (average of 0.105 for 5 species).This lower quantum yield in C4 plants is thought to reflectthe requirement of energy in the C4 cycle. For the C4 NADP-MEtype plant Z. mays and NAD-ME type plant P. miliaceum, quantumyields were also measured over a range of CO2 levels between1 and 20%. In both species maximum quantum yields were obtainedunder 10% CO2 (0.105 O2 quanta-1 in Z. mays and 0.097 O2 quanta-1in P. miliaceum) indicating that at this CO2 concentration thequantum yields are similar to those obtained in C3 plants underCO2 saturation. The high quantum yield values in C4 plants undervery high CO2 may be accomplished by direct diffusion of atmosphericCO2 to bundle sheath cells, its fixation in the C3 pathway,and feedback inhibition of the C4 cycle by inorganic carbon. (Received June 6, 1995; Accepted August 15, 1995) 相似文献
16.
Ethylene and carbon dioxide: Regulation of growth in two perennial aquatic plants, arrowhead and pondweed 总被引:5,自引:0,他引:5
The growth of two perennial aquatic plants, arrowhead {Sagittariapygmaea) and pondweed (Potamogeton distinctus) is greatly promotedby C2H4 and CO2 in the dark; C2H4 and CO2 are synergistic inthis response. C2H4 is produced by these two species. (Received September 10, 1974; ) 相似文献
17.
Growth of segments of embryonic axes and cotyledons excisedfrom dormant or nondormant cocklebur (Xanthium pennsylvanicumWallr.) seeds and CO2 and C2H4 production in these segmentswere examined in relation to the effects of temperature, CO2and C2H4. Both the nondormant axes and cotyledons grew evenat low temperatures below 23°C, but the dormant ones failedto grow. There was only little difference in the CO2 evolutionbetween the nondormant and dormant ones, but both the axis andcotyledon segments from the dormant seeds exhibited little orno C2H4 productivity, unlike the nondormant ones, at low temperatures.However, a high temperature of 33°C caused rapid extensiongrowth and C22H4 production even in dormant axes and cotyledons. The inability of dormant axes and cotyledons to grow disappearedcompletely in the presence of C2H4 at fairly low concentrations.Removal of endogenous CO2 and C2H4 reduced the growth in bothaxes and cotyledons, while exogenous CO2 mainly enhaced axialgrowth although exogenous C2H4 strongly stimulated the growthof both organs. Regardless of the dormant status, however, maximumgrowth of these organs occurred when C2H4 was given togetherwith CO2. We suggest that dormancy in cocklebur seeds is dueto the lack of growing ability in both organs, caused by thelack of C2H4 productivity in both dormant axes and cotyledons,particularly in the former. (Received December 2, 1974; ) 相似文献
18.
Open-flow assays of acetylene reduction activity {ARA)and CO2production in nodulated roots were performed in situ with soybean{Glycine max (L.) Merr.) cv. Kingsoy grown hydroponically withorthophosphate (Pi) nutrition either limiting (low-P) or non-limiting(control) for plant growth. Nodule growth was more limited thanshoot growth by P deficiency. During ARA assays, nitrogenaseactivity declined a few minutes after exposure of the nodulatedroots to C2H2, and this acetyleneinduced decline (C2H2-ID) wastwice as intense at low-P. Moreover, the minimum ARA after theC2H2-ID was reached about 10 min earlier at low-P. The intensityof the C2H2-ID was correlated negatively with nodule mass perplant and positively with the ratio of shoot/nodule mass. Afterinitial exposure to C2H2, the nodulated-root CO2 productionwas transiently stimulated and, moreover, this increase was2-fold higher at low-P. Then, the nodulated-root CO2 productiondecreased with nodule C2H4 production. During the C2H2-ID, thenodule nitrogenase-linked respiration, which was computed asthe variable component of the linear regression between CO2and C2H4 production, was 2-fold higher at low-P. Furthermore,the microscopic observation of nodule sections revealed thatstarch deposits were decreased at low-P. However, nitrogenaseactivity, i.e. ARA before the C2H2-ID, was not affected by Pdeficiency. It is argued that P deficiency increased the C2H2-IDbecause it increased nodule permeability to O2 diffusion. Key words: Acetylene reduction, nitrogen fixation, phosphorus, respiration, soybean, Glycine max (L.) Merr 相似文献
19.
The possible roles of oxygen and carbon dioxide treatments inthe presence or absence of ethylene on tuber dormancy releasein potato (Solanum tuberosumL.) were examined. Using two gascompositions (I: 60% CO220% O220% N2and II: 20%CO240% O240% N2), the phase of tuber dormancyand previous storage temperature were demonstrated to be importantparameters for dormancy release by these gas mixtures. Gas Icaused decreased abscisic acid (ABA) levels within 24 h regardlessof previous storage temperature, although this effect was reversible.Exogenous C2H4, an effective dormancy release agent, also causeddecreased ABA levels within 24 h. It also enhanced dormancyrelease and further promoted ABA losses by gas I. Gas II treatmentled to slight reductions in ABA levels that were further decreasedby C2H4. Sprout length was modelled successfully by multipleregression analysis in terms of glucose and ABA levels withinthe apical eye tissues of Russet Burbank tubers immediatelyafter, and regardless of, previous gas treatments or storagetemperatures. Solanum tuberosum,potato, abscisic acid, ethylene, carbon dioxide, oxygen, dormancy. 相似文献
20.
Excised leaves of a C3-photosynthetic type, Hordeum vulgare,a C4-type, Panicum miliaceum, and an intermediate-type, Panicummilioides, were allowed to take up through their cut ends a1 mM solution of butyl hydroxybutynoate (BHB), an irreversibleinactivator of glycolate oxidase. After 30 to 60 min in BHB,extractable glycolate oxidase activity could not be detectedin the distal quarter of the leaf blades. Following this pretreatment,recovery of 14C-glycolate from 14CO2 incorporated in a 10 minperiod was nearly maximal for each of the three plant types.Labeled glycolate was 51% of the total 14CO2 incorporated forthe C3-species, 36% for the intermediate-species, and 27% forthe C4-species Increased labeling of glycolate was compensatedfor primarily by decreased labeling of the neutral and basicfractions for the C3 and intermediate-type species. In the C4-type,label decreased primarily in the neutral and insoluble fractions,but increased in the basic fraction. A lower rate of glycolatesynthesis is indicative of a lower rate of photorespirationand consistent with a lower O2/CO2 ratio present in the bundle-sheathcells of C4-plants. We conclude that both decreased glycolatesynthesis and the refixation of photorespiratory-released CO2are important in maintaining a lower rate of photorespirationin C4-plants compared to C3 plants. Intermediate glycolate synthesisin Panicum milioldes is consistent with its intermediate levelof O2 inhibition of photosynthesis and intermediate rate ofphotorespiration. (Received May 6, 1978; ) 相似文献