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1.
The expression of photosynthetic traits during and following severe chilling stress of European and tropical maize genotypes 总被引:1,自引:0,他引:1
P. Stamp 《Physiologia plantarum》1987,71(1):73-76
Four genotypes of maize ( Zea mays L.), one from North-West Europe, two from tropical highlands and one from tropical lowlands were grown at 24°C until full expansion of the second leaf. Seedlings were then subjected to 2 days at 5°C, with or without a previous conditioning phase at 10°C for 4 days. After stress plants were allowed to recover at 24°C for 5 days. Previous conditioning protected the tropical lowland variety to some extent against losses in chlorophyll content and ribulose I,5-bisphosphate carboxylase (EC 4.1.1.39) activity by severe chilling stress. Without conditioning heavy losses occurred during the recovery phase. In all other genotypes the values of these traits decreased more with than without conditioning. Phosphoenolpyruvate carboxylase (EC 4.1.1.31) activity was little affected during stress, but declined considerably during the recovery phase, with the exception of the North-West European genotype. Previous conditioning prevented or retarded losses of NADP+ malate dehydrogenase (EC 1.1.1.82) activity during the stress phase. However, at the end of the recovery phase losses were as high with as without conditioning, and activity was very low in one tropical highland genotype and in the tropical lowland genotype. In summary, the chilling stability of photosynthetic traits was better in the North-West European genotype than in the tropical ones. 相似文献
2.
D. T. KRIZEK P. SEMENIUK H. E. MOLINE † R. M. MIRECKI J. A. ABBOTT† 《Plant, cell & environment》1985,8(2):135-142
Abstract. Coleus blumei Benth. (PI No. 354190), a green-leafed cultivar, was exposed to 5°C for 48 or 72 h after pretreatment for 48 h at two levels of photosynthetically active radiation (PAR) (8 and 320 μmol s−1 m−2 ), two temperatures (13 and 20°C), and two abscisic acid (ABA) levels (0 and 200 g m−3 of the racemic mixture). Plants given low PAR for only 48 h prior to chilling treatment (48 or 72 h at 5°C) showed increased protection against chilling injury while those given high PAR were severely injured. The former plants were darker green, contained greater concentrations of chlorophyll- a , chlorophyll- b , total chlorophyll and anthocyanin and generally had a lower abscission rate than the latter plants. There were no differences, however, in chlorophyll- a/b ratio among plants grown at the two PAR levels, two temperatures or two ABA concentrations. Temperature and ABA pretreatment and number of hours at 5°C had no significant effect on chilling injury as measured by leaf chlorosis, but generally had a significant effect on leaf abcission, especially at 3 and 7 d after returning the plants to the greenhouse. Enclosing intact plants or excised shoots in plastic bags to maintain 100% relative humidity during 72 h chilling treatment failed to provide protection against chilling injury. These findings indicate that the protective effects of low PAR applied prior to chilling treatment may be as important or more important than that applied during chilling. They also indicate the importance of making careful measurements of PAR levels when conducting studies on chilling injury. 相似文献
3.
Among grain legumes, faba bean is becoming increasingly popular in European agriculture due to recent economic and environmental
interests. Faba bean can be a highly productive crop, but it is sensitive to drought stress and yields can vary considerably
from season to season. Understanding the physiological basis of drought tolerance would indicate traits that can be used as
indirect selection criteria for the development of cultivars adapted to drought conditions. To assess genotypic variation
in physiological traits associated with drought tolerance in faba bean and to determine relationships among these attributes,
two pot experiments were established in a growth chamber using genetic materials that had previously been screened for drought
response in the field. Nine inbred lines of diverse genetic backgrounds were tested under adequate water supply and limited
water conditions. The genotypes showed substantial variation in shoot dry matter, water use, stomatal conductance, leaf temperature,
transpiration efficiency, carbon isotope discrimination (Δ13C), relative water content (RWC) and osmotic potential, determined at pre-flowering vegetative stage. Moisture deficits decreased
water usage and consequently shoot dry matter production. RWC, osmotic potential, stomatal conductance and Δ13C were lower, whereas leaf temperature and transpiration efficiency were higher in stressed plants, probably due to restricted
transpirational cooling induced by stomatal closure. Furthermore, differences in stomatal conductance, leaf temperature, Δ13C and transpiration efficiency characterized genotypes that were physiologically more adapted to water deficit conditions.
Correlation analysis also showed relatively strong relationships among these variables under well watered conditions. The
drought tolerant genotypes, ILB-938/2 and Melodie showed lower stomatal conductance associated with warmer leaves, whereas
higher stomatal conductance and cooler leaves were observed in sensitive lines (332/2/91/015/1 and Aurora/1). The lower value
of Δ13C coupled with higher transpiration efficiency in ILB-938/2, relative to sensitive lines (Aurora/1 and Condor/3), is indeed
a desirable characteristic for water-limited environments. Finally, the results showed that stomatal conductance, leaf temperature
and Δ13C are promising physiological indicators for drought tolerance in faba bean. These variables could be measured in pot-grown
plants at adequate water supply and may serve as indirect selection criteria to pre-screen genotypes. 相似文献
4.
Breakage of Pseudotsuga menziesii seed dormancy by cold treatment as related to changes in seed ABA sensitivity and ABA levels 总被引:1,自引:0,他引:1
The main aims of the present work were to investigate whether a chilling treatment which breaks dormancy of Douglas fir ( Pseudotsuga menziesii (Mirb.) Franco) seeds induces changes in the sensitivity of seeds to exogenous ABA or in ABA levels in the embryo and the megagametophyte, and whether these changes are related to the breaking of dormancy. Dormant seeds germinated very slowly within a narrow range of temperatures (20–30°C), the thermal optimum being approximately 25°C. The seeds were also very sensitive to oxygen deprivation. Treatment of dormant seeds at 5°C improved further germination, and resulted in a widening of the temperature range within which germination occurred and in better germination in low oxygen concentrations. In dry dormant seeds the embryo contained about one-third of the ABA in the megagametophyte. ABA content of both organs increased during the first 4 weeks of chilling. It then decreased sharply in the megagametophyte to the level in the embryo after 7–15 weeks of chilling. At 15°C, a temperature at which dormancy was expressed, the ABA level increased in the embryo and the megagametophyte of dormant unchilled seeds whereas it decreased in the organs of chilled seeds. The longer the chilling treatment, the faster the decrease in ABA after the transfer of seeds from 5°C to higher temperatures, and the decrease was faster at 25 than at 15°C. These results suggest that the breaking of dormancy by cold was associated with a lower capacity of ABA biosynthesis and/or a higher ABA catabolism in the seeds subsequently placed at 15 or 25°C. Moreover, the chilling treatment resulted in a progressive decrease in the sensitivity of seeds to exogenous ABA. However, seeds remained more sensitive to ABA at 15 than at 25°C. The possible involvement of ABA synthesis and of responsiveness of seeds to ABA in the breaking of dormancy by cold treatment is discussed. 相似文献
5.
This paper is a continuation of our studies related to the response of two tomato cultivars: Robin and New Yorker to chilling:
the later is more tolerant to chilling than the former one (Starck et al. 1994). The concentration of ABA in the xylem sap and ABA delivery rate (calculated as the amount of ABA exuded in 2h from
the cut stump, following shoot removal) were estimated by ELISA. The relative water content (RWC) of the leaf blades and stomatal
resistance (RS) were also measured. Tomato plants were grown in a greenhouse, under noncontrolled conditions. Before chilling
some of the plants were drought hardened for 10 days (H). As an consequence of water deficit only New Yorker growth slightly
decreased. Plants were chilled to 2–5 °C during three consecutive, 16-h nights, preceded by warm days, which caused a decrease
in the RWC of leaf blades. Chilling did not decreased leaf blade hydration significantly, but drastically increased the concentration
of ABA in the xylem sap in more chilling tolerant cv. New Yorker only. The delivery rate of ABA was markedly enhanced in both cultivars, but much more in New Yorker. Drought hardening
increased ABA delivery rate in cv. Robin only, especially after chilling. The lack of correlation between changes in the RWC of leaf blades after low temperature
treatment and the concentration of ABA in the xylem sap as well as its delivery rate suggest, that in both tomato cultivars
chilling increased ABA level directly, not as an secondery effect of temperature-induced water deficit. 相似文献
6.
During the first hours of chilling, bean (Phaseolus vulgaris L., cv Mondragone) seedlings suffer severe water stress and wilt without any significant increase in leaf abscisic acid (ABA) content (P. Vernieri, A. Pardossi, F. Tognoni [1991] Aust J Plant Physiol 18: 25-35). Plants regain turgor after 30 to 40 h. We hypothesized that inability to rapidly synthesize ABA at low temperatures contributes to chilling-induced water stress and that turgor recovery after 30 to 40 h is mediated by changes in endogenous ABA content. Entire bean seedlings were subjected to long-term (up to 6 d) chilling (3°C, 0.2-0.4 kPa vapor pressure deficit, 100 μmol·m−2·s−1 photosynthetic photon flux density, continuous fluorescent light). During the first 24 h, stomata remained open, and plants rapidly wilted as leaf transpiration exceeded root water absorption. During this phase, ABA did not accumulate in leaves or in roots. After 24 h, ABA content increased in both tissues, leaf diffusion resistance increased, and plants rehydrated and regained turgor. No osmotic adjustment was associated with turgor recovery. Following turgor recovery, stomata remained closed, and ABA levels in both roots and leaves were elevated compared with controls. The application of ABA (0.1 mm) to the root system of the plants throughout exposure to 3°C prevented the chilling-induced water stress. Excised leaves fed 0.1 mm ABA via the transpiration stream had greater leaf diffusion resistance at 20 and 3°C compared with non-ABA fed controls, but the amount of ABA needed to elicit a given degree of stomatal closure was higher at 3°C compared with 20°C. These findings suggest that endogenous ABA may play a role in ameliorating plant water status during chilling. 相似文献
7.
Antioxidant compound responses to chilling stress in differentially sensitive inbred maize lines 总被引:24,自引:0,他引:24
D. Mark Hodges Christopher J. Andrews Douglas A. Johnson Robert I. Hamilton 《Physiologia plantarum》1996,98(4):685-692
Chilling temperatures increase the amounts of potentially lethal toxic oxygen compounds present within plants. These toxic oxygen compounds can be scavenged by antioxidant compounds such as ascorbate and β-carotene. Three developmental stages (first, third and fifth leaf) of four inbred lines of maize ( Zea mays L.) exhibiting differential sensitivity to chilling were examined in order to determine if the chilling-sensitive line had lower concentrations of antioxidant compounds than did the tolerant lines. Plants were exposed to one of three treatments: (1) control (25°C constant), (2) control treatment plus a short-term chilling exposure of 11°C one day prior to harvesting, and (3) long-term (11°C constant) chilling exposure. Total ascorbate, total glutathione, β-carotene, α-tocopherol and chlorophyll contents were quantified, and ratios of dehydroascorbate/ascorbate and reduced/oxidized glutathione were determined. Lower concentrations of β-carotene were found in the chilling-sensitive relative to those in the chilling-tolerant lines for the first-leaf stage under both short- and long-term chilling treatments. Concentrations of total ascorbate and glutathione and β-carotene in the chilling-sensitive line increased as the chilling treatment progressed and as the plants developed until they ultimately became either significantly higher or no different relative to the tolerant lines. Results suggest that this sensitive line became less sensitive to chilling-induced oxidative stress with development. 相似文献
8.
Banana is a tropical crop cultivated in warm places. Chilling stress in Egypt is making banana crops less
productive. Abscisic acid (ABA), a key plant hormone, regulates metabolic and physiological processes and
protects plants from a variety of stresses. In vitro growing banana shoots were pre-treated with ABA at four
concentrations (0, 25, 50, and 100 mM) and chilled at 5°C for 24 h, followed by a six-day recovery period at
25°C. By comparing ABA treatments to both positive and negative controls, physiological and biochemical
changes were investigated. Chilling stress (5°C) caused a considerable increase in lipid peroxidation and ion
leakage and reduced photosynthetic pigments in cold-treated plantlets. Increasing the concentration of ABA
to 100 µM enhanced the response to chilling stress. ABA had a major effect on mitigating chilling injury in
banana shoots by keeping cell membranes stable and lowering the amount of ion leakage and lipid peroxidation.
Also, ABA significantly maintained the photosynthetic pigment concentration of banana shoots; accumulated
higher amounts of total soluble carbohydrates and proline; and increased DPPH radical scavenging activity.
Furthermore, ABA treatment enhanced cold tolerance in chilling-stressed banana shoots through the regulation
of antioxidant enzyme activity. Overall, the results show that ABA is a good choice for protecting banana shoots
from the damage caused by chilling stress. 相似文献
9.
Drought enhances maize chilling tolerance. II. Photosynthetic traits and protective mechanisms against oxidative stress 总被引:9,自引:0,他引:9
In the present research we studied the photosynthetic traits and protective mechanisms against oxidative stress in two maize ( Zea mays L.) genotypes differing in chilling sensitivity (Z7, tolerant and Penjalinan, sensitive) subjected to 5°C for 5 days, with or without pretreatment by drought. The drought pretreatment decreased the symptoms of chilling injury in Penjalinan plants estimated as necrotic leaf area and maximum quantum yield of photosystem II. Furthermore, drought pretreatment diminished the level of lipid peroxidation caused by chilling in Penjalinan plants. After one day of recovery from chilling the Z7 and drought-pretreated Penjalinan plants showed higher net photosynthesis rates than the non-drought-pretreated Penjalinan plants, thereby decreasing the probability of generating reactive oxygen species. The greater net photosynthesis was correlated with the greater NADP-malate dehydrogenase activity. No differences in either the de-epoxidation state of the xanthophyll cycle or the antioxidant enzyme activities were found among the chilled groups of plants. However, a drastic decrease in ascorbate content was observed in chilled Penjalinan plants without drought pretreatment. As we found an increase of H2 O2 content after drought pretreatment, we suggest its involvement as a signal in the drought-enhanced chilling tolerance of maize. 相似文献
10.
Growth, photosynthesis and assimilate partitioning in Lolium temulentum exposed to chilling temperatures 总被引:5,自引:0,他引:5
Christopher J. Pollock Eric J. Lloyd John L. Stoddart Howard Thomas 《Physiologia plantarum》1983,59(2):257-262
Vegetative plants of Lolium temulentum L, grown at 20°C with an 8 h photoperiod were transferred to either 5 or 2°C (8 h photoperiod) at 4th leaf maturity. Measurement of dry weight gain indicated a marked decline in relative growth rate below 5°C, with growth being reduced as much between 5 and 2°C as between 20 and 5°C. This reduction was not associated with increased mortality and was reversible if plants were returned to 20°C. Tissue explants from cold-treated plants retained the ability to extend if returned to 20°C Rates of extension in explants were less temperature sensitive than the relative growth rates observed in intact plants. Measurements of photosynthetic capacity, and of the patterns of accumulation of reserve carbohydrate in plants exposed to different temperatures, suggested that the inhibition of growth caused by chilling is not caused by an inability of the plants to fix sufficient carbon. 相似文献
11.
Vânia Aparecida Silva Fernanda Manso Prado Werner Camargos Antunes Rita Márcia Cardoso Paiva Maria Amélia Gava Ferrão Alan Carvalho Andrade Paolo Di Mascio Marcelo Ehlers Loureiro Fábio Murilo DaMatta Andréa Miyasaka Almeida 《Plant Growth Regulation》2018,85(2):221-229
The role of abscisic acid (ABA) in drought tolerance of Coffea canephora is unknown. To determine whether ABA is associated with drought tolerance and if the use of tolerant rootstocks could increase ABA and drought tolerance, we performed reciprocal grafting experiments between clones with contrasting tolerance to drought (clone 109, sensitive; and clone 120, tolerant). Plants were grown in large (120 L) pots in a greenhouse and subjected to drought stress by withholding irrigation. The non-grafted 120 plants and graft treatments with 120 as a rootstock showed a slower reduction of predawn leaf water potential (Ψpd) and a lower negative carbon isotopic composition ratio compared with the other grafting combinations in response to drought. The same 120 graft treatments also showed higher leaf ABA concentrations, lower levels of electrolyte leakage, and lower activities of ascorbate peroxidase and catalase under moderate (Ψpd?=???1.0 or ??1.5 MPa) and severe (Ψpd?=???3.0 MPa) drought. Root ABA concentrations were higher in plants with the 120 rootstocks regardless of watering regime. The 120 shoots could also contribute to drought tolerance because treatment with 120/109 rootstock/scion combination showed postponed dehydration, higher leaf ABA concentration, and lower leaf electrolyte leakage compared with the sensitive clone. We conclude that both the shoot and root systems of the tolerant clone can increase the concentrations of ABA in leaves in response to drought. This further suggests that ABA is associated with a delayed onset of severe water deficit and decreased oxidative damage in C. canephora. 相似文献
12.
Frost tolerance has been reported in the shoots of wild, tuberiferous potato species such as Solanum commersonii when the plants are grown in either field or controlled conditions. However, these plants can survive as underground tubers and avoid unfavorable environmental conditions altogether. As such, leaf growth and photosynthesis at low temperature may not be required for survival of the plants. In order to determine the temperature sensitivity of S. commersonii shoots, we examined leaf growth, development and photosynthesis in plants raised at 20/16°C (day/night). 12/9°C and 5/2°C. S. commersonii leaves grown at 5°C exhibited a marked decrease in leaf area and in total chlorophyll (Chl) content per leaf area when compared with leaves grown at 20°C. Furthermore, leaves grown at 5°C did not exhibit the expected decrease in either water content or susceptibility to low-temperature-induced photoinhibition that normally characterizes cold acclimation in frost-tolerant plants. Measurements of CO2 -saturated O2 evolution showed that the photosynthetic apparatus of 5°C plants was functional, even though the efficiency of photosystem II photochemistry was reduced by growth at 5°C. A decrease in the resolution of the M-peak in the slow transients for Chl a fluorescence in leaves grown at 12 and 5°C and in all leaves exposed to high light at 5°C indicated that low temperature significantly affected processes on the reducing side of QA , the primary quinone electron acceptor in photosystem II. Thus S. commarsonii exhibits the characteristics of a plant that is limited by chilling temperatures. Although S. commersonii can tolerate light frosts, its sensitivity to chilling temperatures may result in shoot dieback in winter in its native habitat. The plants may avoid both chilling and freezing temperatures by overwintering as underground tubers. 相似文献
13.
Effect of abscisic acid on chilling injury of zucchini squash 总被引:3,自引:0,他引:3
Chien Yi Wang 《Journal of Plant Growth Regulation》1991,10(1):101-105
The endogenous levels of abscisic acid (ABA) in zucchini squash were increased by temperature conditioning at 10°C for 2 days. This temperature conditioning treatment reduced the severity of chilling injury in the squash during subsequent storage at 2.5°C. The ABA levels remained higher in treated squash than in untreated samples throughout the storage. Direct treatments of squash with ABA at 0.5 and 1.0 mM before storage at 2.5°C increased ABA levels in the tissue and were also effective in reducing chilling injury. 相似文献
14.
Chien Yi Wang 《Journal of Plant Growth Regulation》1991,10(1-4):101-105
The endogenous levels of abscisic acid (ABA) in zucchini squash were increased by temperature conditioning at 10°C for 2 days. This temperature conditioning treatment reduced the severity of chilling injury in the squash during subsequent storage at 2.5°C. The ABA levels remained higher in treated squash than in untreated samples throughout the storage. Direct treatments of squash with ABA at 0.5 and 1.0 mM before storage at 2.5°C increased ABA levels in the tissue and were also effective in reducing chilling injury. 相似文献
15.
Jean Aghofack-Nguemezi Alexander Christmann Silvia Frosch Antoine Trémoliéres Edgar Wagner 《Physiologia plantarum》1991,83(3):346-352
Seedlings of Phaseolus aureus ROXB were grown under 12/12 h light/dark cycles with the light period at 32.5°C and darkness at 10°C (normal conditions N) or with light at 10°C and darkness at 32.5°C (inverse conditions, I). I-conditions affected the level of chlorophyll and carotenoids (very low), monogalactosyldiacylgycerol (low) and phosphatidylinositol (high) in the leaves. Leaves of I-seedlings showed a sharp and durable decline of relative water content during the low temperature phase. For the N-seedlings, loss of water was restricted to the end of this period. The loss of water was accompanied by visible symptoms of wilting at specific times of day. Although the pigment content remained nearly unchanged, ABA content of leaves of both N-and I-seedlings increased during water stress. Upon return to the warm period, ABA level continued to increase after the leaves had regained turgor, this 'after stress'increase being more pronounced in the leaves of I-seedlings. Exogenous application of ABA induced a slight increase in the content of phospholipids in N- and I-leaves and a decrease in free fatty acids, whereas monogalactosyldiacylglycerol content was significantly reduced in N-leaves after application of ABA. Upon transfer of I-plants to 20°C for 12 h during the light period, pigment and chloroplastic lipid content increased rapidly whereas upon a further exposure to 10°C in light, pigments and especially monogalactosyldiacylglycerol were lost. The control of pigment and lipid metabolism and the role of ABA during chilling stress are discussed. 相似文献
16.
Abscisic Acid-induced chilling tolerance in maize suspension-cultured cells 总被引:7,自引:3,他引:4 下载免费PDF全文
The induction of chilling tolerance by abscisic acid (ABA) in maize (Zea mays L. cv Black Mexican Sweet) suspension cultured cells was examined. Cell viability during exposure to chilling was estimated by triphenyl tetrazolium chloride reduction immediately after chilling and a filter paper growth assay. Both methods yielded comparable results. Chilling tolerance was induced by transferring 5-day-old cultures (late log phase) to a fresh medium containing ABA (10 to 100 micromolar). The greatest chilling tolerance was achieved with ABA at 100 micromolar. Growth of cells was inhibited at this concentration. After a 7-day exposure to 4°C in the dark, the survival of ABA-treated cells (100 micromolar ABA, 28°C for 24 h in the dark) was sevenfold greater than untreated cells. Effective induction of chilling tolerance was first observed when cells were held at 28°C for 6 hours after adding ABA. No tolerance was induced if the culture was chilled at the inception of ABA treatment. Induction of chilling tolerance was inhibited by cycloheximide. These results indicate that ABA is capable of inducing chilling tolerance when ABA-treated cells are incubated at a warm temperature before exposure to chilling, and this induction requires de novo synthesis of proteins. 相似文献
17.
Adrienn Guóth Irma Tari Ágnes Gallé Jolán Csiszár Attila Pécsváradi László Cseuz László Erdei 《Journal of Plant Growth Regulation》2009,28(2):167-176
Water status parameters, flag leaf photosynthetic activity, abscisic acid (ABA) levels, grain yield, and storage protein contents
were investigated in two drought-tolerant (Triticum aestivum L. cv. MV Emese and cv. Plainsman V) and two drought-sensitive (cvs. GK élet and Cappelle Desprez) wheat genotypes subjected
to soil water deficit during grain filling to characterize physiological traits related to yield. The leaf water potential
decreased earlier and at a higher rate in the sensitive than in the tolerant cultivars. The net CO2 assimilation rate (P
N) in flag leaves during water deficit did not display a strict correlation with the drought sensitivity of the genotypes.
The photosynthetic activity terminated earliest in the tolerant cv. Emese, and the senescence of flag leaves lasted 7 days
longer in the sensitive Cappelle Desprez. Soil drought did not induce characteristic differences between sensitive and tolerant
cultivars in chlorophyll a fluorescence parameters of flag leaves during post-anthesis. Changes in the effective quantum yield of PSII (ΦPSII) and the photochemical quenching (qP) depended on the genotypes and not on the sensitivity of cultivars. In contrast, the
levels of ABA in the kernels displayed typical fluctuations in the tolerant and in the sensitive cultivars. Tolerant genotypes
exhibited an early maximum in the grain ABA content during drought and the sensitive cultivars maintained high ABA levels
in the later stages of grain filling. In contrast with other genotypes, the grain number per ear did not decrease in Plainsman
and the gliadin/glutenin ratio was higher than in the control in Emese during drought stress. A possible causal relationship
between high ABA levels in the kernels during late stages of grain filling and a decreased grain yield was found in the sensitive
cultivars during drought stress. 相似文献
18.
Antioxidant enzyme responses to chilling stress in differentially sensitive inbred maize lines 总被引:13,自引:3,他引:10
Hodges D. Mark; Andrews Christopher J.; Johnson Douglas A.; Hamilton Robert I. 《Journal of experimental botany》1997,48(5):1105-1113
Antioxidant enzyme activities were determined at the first,third and fifth leaf stages of four inbred lines of maize (Zeamays L.) exhibiting differential sensitivity to chilling. Plantswere exposed to a photoperiod of 16:8 L:D for one of three treatments:(a) control (25C), (b) control treatment plus an exposure toa short-term chilling shock (11C 1 d prior to harvesting),and (c) long-term (11 C constant) chilling exposure. Catalase(CAT; EC 1.11.1.6
[EC]
), ascorbate peroxidase (ASPX; EC 1.11.1.11
[EC]
),superoxide dismutase (SOD; EC 1.15.1.1
[EC]
), glutathione reductase(GR; EC 1.6.4.2
[EC]
), and mono-dehydroascorbate reductase (MDHAR;EC 1.6.5.4
[EC]
) activities were assessed. Reducing and non-reducingsugars and starch concentrations were determined as generalmetabolic indicators of stress. Reduced activities of CAT, ASPX,and MDHAR may contribute to limiting chilling tolerance at theearly stages of development in maize. Changes in levels of sugarand starch indicated a more rapid disruption of carbohydrateutilization in comparison to photosynthetic rates in the chilling-sensitiveline under short-term chilling shocks and suggested a greaterdegree of acclimation in the tolerant lines over longer periodsof chilling. Key words: Antioxidant enzymes, differential chilling sensitivity, maize, soluble carbohydrates, Zea mays 相似文献
19.
Hardening, abscisic acid, proline and freezing resistance in two winter wheat varieties 总被引:8,自引:1,他引:7
Two varieties of winter wheat ( Triticum aestivum L.) differing in freezing resistance ("Holme" from Sweden, freezing resistant, and "Amandus" from Germany, less freezing resistant) were hardened for five weeks by gradually reducing the day/night temperature from 20°C/15°C during the first week to 2° C/0° C during the fifth week and the photoperiod from 15 to 9 h. This treatment increased the freezing resistance of both varieties in comparison to unhardened control plants. Hardening caused an increase in osmolarity of cell sap and in the levels of proline and abscisic acid (ABA). Increase in osmolarity preceded the increase in ABA level, and proline levels increased later than ABA levels. Holme had higher values of osmolarity as well as higher levels of ABA and proline. but the differences between the two varieties were significant only for proline. Since the pressure potential remained constant or increased slightly during the hardening period, it is suggested that the accumulation of ABA is due to the hardening process and not to simple water stress caused by cold-induced inhibition of water uptake by the root.
Spraying hardened plants with 10−4 M ABA 24 h before a freezing test increased freezing resistance in both varieties, but did not obliterate the differences in freezing resistance between the two varieties. Spraying hardened plants with an aqueous proline solution (10%, w/v) was without effect on freezing resistance. It is concluded that the hardening procedure causes an accumulation of ABA in winter wheat leaves and that ABA is involved in the chain of events leading to freezing resistance. 相似文献
Spraying hardened plants with 10
20.
Increased chilling tolerance and altered carbon metabolism in tomato leaves following application of mechanical stress 总被引:1,自引:0,他引:1
We investigated the effects of brushing on the chilling tolerance and metabolism of nonstructural carbohydrates (soluble sugars and starch) in tomato leaves before, during and after a chilling stress. Tomato plants ( Lycopersicon esculentum Mill. cv. Caruso) were cultivated either without mechanical stress application (control plants) or with daily brushing treatments for 15 days (brushed plants), prior to a 7-day chilling treatment (8/5°C day/night). Brushing resulted in shorter plants with a 34% reduction in leaf dry weight per area and a 59% reduction of soluble sugars and starch, on a dry weight basis. The sugar to starch ratio was not affected by brushing. A greater chilling tolerance in the brushed plants was demonstrated by the maintenance of a significantly higher PSII efficiency in brushed plants (42%) compared to that of the control plants (30%) after 7 days of chilling treatment, less visible damage to the leaf tissue, and a more rapid resumption of growth during 3 days of recovery as compared to control plants. During the chilling treatment levels of soluble sugars per leaf dry weight increased 15-fold in the brushed plants and 5-fold in control plants. In the present study we have demonstrated that brushing can increase chilling tolerance in tomato plants. The observed differences in chilling tolerance and concentration of soluble sugars in the leaves may indicate an involvement of soluble sugar levels in acclimation to chilling. 相似文献