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1.
Relationship between Polyamines and Anaerobic Respiration of Wheat Seedling Root under Water-Logging Stress 总被引:1,自引:0,他引:1
H. Y. Du D. X. Liu G. T. Liu H. P. Liu R. Kurtenbach 《Russian Journal of Plant Physiology》2018,65(6):874-881
To elucidate the relationship between polyamines and anaerobic respiration of wheat (Triticum aestivum L.) seedling root under water-logging stress, the contents of polyamines (PAs), lactate and alcohol, and the activities of anaerobic respiration enzymes were investigated in seedling roots of two wheat cultivars, Yumai no. 18 and Yangmai no. 9. On the 5th day after water-logging treatment, spermidine (Spd) and spermine (Spm) contents increased significantly, pyruvate decarboxylase (PDC) activity increased and there was no difference between two cultivars. Alcohol dehydrogenase (ADH) activity and alcohol content in Yangmai no. 9 increased more markedly than Yumai no. 18, while lactate dehydrogenase (LDH) activity and the lactate content in the Yumai no. 18 increased more markedly than Yangmai no. 9. Treatments with exogenous Spd and Spm resulted in enhancing the increases in ADH activity, alcohol content, and the levels of Spd and Spm. This concomitantly inhibited the increases in LDH activity and lactate content in Yumai no. 18 under water-logging stress, alleviating stress-induced injury to the seedlings. Treatment with exogenous inhibitor methylglyoxyl-bis-guanylhydrazone (MGBG), resulted in reducing the increases in ADH activity, alcohol content, and Spd and Spm levels, promoting the increases in LDH activity and lactate content in Yangmai no. 9 under water-logging stress, and aggravating the stress-induced injury to the seedlings. The results suggested that under water-logging stress, increased Spd and Spm could facilitate the tolerance of wheat seedling to the stress by enhancing the increases in ADH activity and alcohol content, and inhibiting the increases in LDH activity and lactate content. 相似文献
2.
温度和光照强度对不同品质类型小麦旗叶光合特性和衰老的影响 总被引:20,自引:0,他引:20
以两个蛋白质含量不同的小麦品种豫麦34(高蛋白)和扬麦9号(低蛋白)为材料,研究不同温光条件对小麦灌浆期旗叶光合特性和衰老的影响.结果表明:高温、弱光处理显著降低了小麦旗叶净光合速率(Pn)及叶绿素荧光参数Fv/Fm和ΦPSⅡ,但高温和弱光对小麦旗叶造成伤害的生理机制不同,高温主要降低了叶绿素含量(SPAD值)和Pn,灌浆后期Pn下降幅度达50%;而弱光主要降低了叶绿素荧光参数,抑制了光合系统PSⅡ的活性.高温使小麦旗叶丙二醛(MDA)含量升高,超氧化物歧化酶(SOD)活性和可溶性蛋白质含量下降,加速了植株衰老;而弱光下SOD活性较高,小麦衰老进程较高温缓慢,植株对弱光的耐受性较强.豫麦34对高温、弱光逆境的反应比扬麦9号敏感. 相似文献
3.
The mechanisms of capsicum growth in response to differential light availabilities are still not well elucidated. Hereby,
we analyzed differential light availabilities on the relationship between stomatal characters and leaf growth, as well as
photosynthetic performance. We used either 450–500 μmol m−2 s−1 as high light (HL) or 80–100 μmol m−2 s−1 as low light (LL) as treatments for two different cultivars. Our results showed that the stomatal density (SD) and stomatal
index (SI) increased along with the leaf area expansion until the peak of the correlation curve, and then decreased. SD and
SI were lower under the LL condition after three days of leaf expansion. For both cultivars, downregulation of photosynthesis
and electron transport components was observed in LL-grown plants as indicated by lower light- and CO2-saturated photosynthetic rate (P
max and RuBPmax), quantum efficiency of photosystem II (PSII) photochemistry (ΦPSII), electron transport rate (ETR) and photochemical quenching of fluorescence (qp). The observed inhibition of the photosynthesis could be explained by the decrease of SD, SI, Rubisco content and by the
changes of the chloroplast. The low light resulted in lower total biomass, root/shoot ratio, and the thickness of the leaf
decreased. However, the specific leaf area (SLA) and the content of leaf pigments were higher in LL-treatment. Variations
in the photosynthetic characteristics of capsicum grown under different light conditions reflected the physiological adaptations
to the changing light environments. 相似文献
4.
Several studies have found the photosynthetic integration in clonal plants to response to resource heterogeneity, while little
is known how it responses to heterogeneity of UV-B radiation. In this study, the effects of heterogeneous UV-B radiation (280–315
nm) on gas exchange and chlorophyll fluorescence of a clonal plant Trifolium repens were evaluated. Pairs of connected and severed ramets of the stoloniferous herb T. repens were grown under the homogeneity (both of ramets received only natural background radiation, ca. 0.6 kJ m−2 d−1) and heterogeneity of UV-B radiation (one of the ramet received only natural background radiation and the other was exposed
to supplemental UV-B radiation, 2.54 kJ m−2 d−1) for seven days. Stomatal conductance (g
s), intercellular CO2 concentration (C
i) and transpiration rate (E) showed no significant differences in connected and severed ramets under homogenous and heterogeneous UV-B radiation, however,
net photosynthetic rate (P
N) and maximum photosynthetic rate (P
max) of ramets suffered from supplemental increased UV-B radiation and that of its connected sister ramet decreased significantly.
Moreover, additive UV-B radiation resulted in a notable decrease of the minimal fluorescence of dark-adapted state (Fo), the electron transport rate (ETR) and photochemical quenching coefficient (qP) and an increase of nonphotochemical quenching (NPQ) under supplemental UV-B radiation, while physiological connection reverse
the results. In all, UV-B stressed ramets could benefit from unstressed ramets by physiological integration in photosynthetic
efficiency, and clonal plants are able to optimize the efficiency to maintain their presence in less favourable sites. 相似文献
5.
Koblížek M. Ciscato M. Komenda J. Kopencký J. Šiffel P. Masojídek J. 《Photosynthetica》1999,37(2):307-323
The dark-adapted cells of the green alga Spongiochloris sp. were exposed to "white light" of 1000 μmol(photon) m−2 s−1 for 2 h and then dark adapted for 1.5 h. Changes of photochemical activities during photoadaptation were followed by measurement
of chlorophyll (Chl) fluorescence kinetics, 77 K emission spectra, photosynthetic oxygen evolution, and pigment composition.
We observed a build-up of slowly-relaxing non-photochemical quenching which led to a decrease of the Fv/Fm parameter and the connectivity. In contrast to the depression of Fv/Fm (35 %) and the rise of non-photochemical quenching (∼ 1.6), we observed an increase in effective absorption cross-section
(20 %), Hill reaction (30 %), photosynthetic oxygen evolution (80 %), and electron transport rate estimated from the Chl fluorescence
analysis (80 %). We showed an inconsistency in the presently used interpretation schemes, and ascribe the discrepancy between
the increase of effective absorption cross-section and the photosynthetic activities on one side and the effective non-photochemical
quenching on the other side to the build-up of a quenching mechanism which dissipates energy in closed reaction centres. Such
a type of quenching changes the ratio between thermal dissipation and fluorescence without any effect on photochemical yield.
In this case the Fv/Fm ratio cannot be used as a measure of the maximum photochemical yield of PS2.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
6.
The changes in photosynthetic efficiency and photosynthetic pigments during dehydration of the resurrection plantSelaginella lepidophylla (from the Chiuhahuan desert, S.W. Texas, USA) were examined under different light conditions. Changes in the photosynthetic
efficiency were deduced from chlorophyll a fluorescence measurements (Fo, Fm, and Fv) and pigment changes were measured by HPLC analysis. A small decrease in Fv/Fm was seen in hydrated stems in high light (650 μmol photons·m−2·s−1) but not in low light (50 μmol photons·m−2·s−1). However, a pronounced decline in Fv/Fm was observed during dehydration in both light treatments, after one to two hours of dehydration. A rise in Fo was observed only after six to ten hours of dehydration. Concomitant with the decrease in photosynthetic efficiency during
dehydration a rise in the xanthophyll zeaxanthin was observed, even in low-light treatments. The increase in zeaxanthin can
be related to previously observed photoprotective non-photochemical quenching of fluorescence in dehydrating stems ofS. lepidophylla. We hypothesize that under dehydrating conditions even low light levels become excessive and zeaxanthin-related photoprotection
is engaged. We speculate that these processes, as well as stem curling and self shading (Eickmeier et al. 1992), serve to
minimize photoinhibitory damage toS. lepidophylla during the process of dehydration. 相似文献
7.
The contents of covalently conjugated polyamines (CC-PAs) and noncovalently conjugated polyamines (NCC-PAs) to deoxyribonucleic
acid-protein (DNP) isolated from wheat (Triticum aestivum L.) seedling roots under osmotic stress were detected. Results showed that after osmotic stress treatment for 7 d, the levels
in NCC-spermine (NCC-Spm) and NCC-spermidine (NCC-Spd) of drought-tolerant Yumai No. 18 cv. increased more markedly than that
of drought-sensitive Yangmai No. 9 cv., while the NCC-putrescine (NCC-Put) could not be statistically detected in two cultivars.
Exogenous Spm treatment alleviated osmotic stress injury to Yangmai No. 9 cv. seedlings, coupled with marked increases of
NCC-Spm and NCC-Spd levels of this cultivar. Under PEG osmotic stress, the concomitant treatment of drought-tolerant Yumai
No. 18 cv.seedlings with methylglyoxyl-bis (guanylhydrazone) (MGBG), an inhibitor of S-adenosylmethionine decarboxylase (SAMDC), aggravated osmotic stress injury to this cultivar, coupled with market decreases
of the NCC-Spm and NCC-Spd levels. The levels in CC-Put and CC-Spd of drought-tolerant Yumai No. 18 cv. increased more markedly
than that of drought-sensitive Yangmai No. 9 cv. Under osmotic stress. The treatment of drought-tolerant Yumai No. 18 cv.
seedlings with phenanthrolin (o-Phen), an inhibitor of transglutaminase (TGase), aggravated osmotic stress injury to this
cultivar, coupled with a reduction of sum contents of CC-Put+CC-Spd. These results suggested that NCC-Spm and NCC-Spd, together
with CC-Put and CC-Spd, in DNP of roots could enhance tolerance of the wheat seedlings to osmotic stress. 相似文献
8.
Chilling stress and chilling tolerance of sweet potato as sensed by chlorophyll fluorescence 总被引:2,自引:0,他引:2
We studied changes in the chlorophyll (Chl) fluorescence components in chilling-stressed sweet potato (Ipomoea batatas L. Lam) cv. Tainung 57 (TN57, chilling-tolerant) and cv. Tainung 66 (TN66, chilling-susceptible). Plants under 12-h photoperiod
and 400 μmol m−2 s−1 irradiance at 24/20 °C (day/night) were treated by a 5-d chilling period at 7/7 °C. Compared to TN66, TN57 exhibited a significantly
greater basic Chl fluorescence (F0), maximum fluorescence (Fm), maximum fluorescence yield during actinic irradiation (Fm′ ), and the quantum efficiency of electron transport through photosystem 2, PS2 (ΦPS2). Chilling stress resulted in decrease in the potential efficiency of PS2 (Fv/Fm), ΦPS2, non-photochemical fluorescence quenching (NPQ), non-photochemical quenching (qN), and the occurrence of chilling injury in TN66. Chilling increased the likelihood of photoinhibition, characterized by a
decline in the Chl fluorescence of both cultivars, and photoinhibition during low temperature stress generally occurred more
rapidly in TN66. 相似文献
9.
Leaf Photosynthesis in Eight Almond Tree Cultivars 总被引:2,自引:0,他引:2
Response of gas exchange traits to irradiance were studied in eight almond tree (Prunus amygdalus) cultivars: Desmayo Largueta, Falsa Barese, Garrigues, Lauranne, Marcona, Masbovera, Nonpareil and Ramillete, grafted on
a hybrid rootstock almond × peach GF-677. From these responses cultivars can be classified from the best to the worst photosynthetic
performance as follows: Falsa Barese, Masbovera, Marcona, Nonpareil, Ramillete, Desmayo Largueta, Lauranne and Garrigues.
The highest net photosynthetic rate was 20.3 μmol m−2 s−1 in Falsa Barese. In the absence of water stress, photosynthetic rate was not limited by stomatal conductance. Consequently,
non-stomatal limitations prevailed under such conditions.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
10.
Wiesław I. Gruszecki Małgorzata Gospodarek Anna Ja kowska Edward piewla 《Acta Physiologiae Plantarum》2006,28(2):127-136
The effect of prolonged illumination (60 min) with photosynthetically active monochromatic radiation of low intensity (3 μmol
m−2 s−1) and high intensity (60 μmol m−2 s−1), corresponding to the physiological conditions and light stress conditions, respectively, was studied in the algae Nitellopsis obtusa. Illumination of Nitellopsis obtusa cells with strong light was associated with activation of the xanthophyll cycle, manifested by the deepoxidation of violaxanthin
and accumulation of antheraxanthin and zeaxanthin. At the same time, the efficient singlet excitation quenching in the photosynthetic
apparatus was activated, as demonstrated by the decrease in the intensity of the chlorophyll a fluorescence emission by ca 50 %. The difference of the fluorescence excitation spectra recorded before and after the light treatment match the difference
absorption spectrum of the xanthophyll cycle pigments. The illumination with low light intensity resulted also in the chlorophyll
a fluorescence quenching but the effect was very small (less than 10 %). The fluorescence quenching is interpreted in terms
of the energy transfer between the Qy energy level of chlorophyll a and the 21 Ag
− energy level of zeaxanthin. The singlet energy levels of carotenoids, corresponding to the green spectral region, are also
taken into consideration in the interpretation of the excitation energy exchange between the carotenoids and chlorophylls.
Possible molecular mechanisms involved in the activation of the strong and the weak excitation quenching, including violaxanthin
isomerization, and possible physiological functions of such pathways of energy transfer are discussed. 相似文献
11.
The aim of this study was to investigate post-anthesis N redistribution from the roots to other organs in the wheat plant.
Two cultivars of spring wheat (Triticum aestivum L.) Sport and WL were grown to maturity in culture solution with stepwise-decreasing N supply and 15N before sampling. The N concentration of dry weight in the roots decreased from anthesis to full maturity. At maturity the
root N concentration was 5.5 mg g−1 dry weight for Sport and 4.9 mg g−1 dry weight for WL, while the main shoot N concentration was 2.1 mg g−1 dry weight for Sport and 2.2 mg g−1 dry weight for WL. The roots were a major sink for N taken up post-anthesis and contained the main proportion of the 15N during the whole post-anthesis period. The N redistributed from the roots contributed 24.3% of the total N amount in the
grains at maturity in cv Sport and 8.7% in cv WL. For cv Sport, 46.3% of the root N amount was redistributed to other parts
of the plant and for WL 25.4%. The tiller grains were supplied with N from the 15N applied post-anthesis to a higher degree than the main shoot grains. The transport capability was maintained until 12 days
after complete yellowness. We concluded that wheat has a great ability to redistribute nitrogen from the root system to the
grains. 相似文献
12.
Z. Shu L. Shao H. -Y. Huang X. -Q. Zeng Z. -F. Lin G. -Y. Chen C. -L. Peng 《Photosynthetica》2009,47(4):548-558
In the present study, we investigated the antioxidative potential in leaves of the chromatic (CC) versus green (GC) Amaranthus tricolor L. under moderate high-temperature stress at 45°C. Before heat stress, CC had significantly higher levels of betacyanins
[about 3.2 mg g−1(FM)] than the green [1.8 mg g−1(FM) (p<0.01), while similar chlorophyll (Chl) content [about 2 mg g−1(FM)] was observed between both cultivars. After exposure to high temperature (45°C) for 6 days, betacyanins in leaves of
CC were remarkably increased (about 2 times of that in control samples grown at 30°C). In contrast, betacyanins in GC significantly
decreased by 56% in comparison with that of the control. Chl level in CC was higher than that in GC after heat stress for
6 days. Flavonoids and total phenolics in both cultivars were increased, but much more in CC. Significantly less H2O2 accumulation was observed in the leaves and stems of CC than in those of GC under heat stress. Interestingly, much stronger
circadian oscillation in fluorescence was observed in both cultivars after treatment at 45°C, which suggested that heat stress
stimulates endogenous rhythms of photosystem II (PSII). Under moderate high-temperature stress, Chl fluorescence parameters
Fv/Fm (maximum quantum yield of PSII), qP (coefficient of photochemical quenching), ΦPSII (effective PSII quantum yield), and ETR (electron transport rate) exhibited a gradual decrease, NPQ (nonphotochemical quenching)
showed a slight increase followed by a gradual decline, whereas Fo (minimum fluorescence of a dark-adapted leaf) increased continuously. In contrast to GC, after 120 h of high-temperature
treatment, CC exhibited significantly lower Fo level, and higher levels of Fv/Fm and NPQ. It is clear that PSII in CC was more stable than that in GC. The results indicate that betacyanins are an effective
antioxidant, and probably contribute greatly to the higher thermal stability of PSII and higher tolerance to heat stress. 相似文献
13.
The impact of ozone fumigation and fertilization on chlorophyll fluorescence of birch leaves (Betula pendula) 总被引:1,自引:0,他引:1
Sergej Shavnin Stefan Maurer Rainer Matyssek Wolfgang Bilger C. Scheidegger 《Trees - Structure and Function》1999,14(1):10-16
The impact of ozone fumigation on chlorophyll a fluorescence parameters and chlorophyll content of birch trees grown at high and low fertilization were studied for 6-, 8-,
and 12-week old leaves. Fluorescence parameters were measured with a portable fluorometer with its fibre optics tightly inserted
in a gas exchange cuvette at light intensities from 0 to 220 μmol photons m−2 s−1. Ozone caused significant changes of primary photosynthetic reactions: a decrease of the quantum yield of photosystem II
and an increase of non-photochemical quenching. In all leaves a biphasic light response of non-photochemical quenching was
observed. Ozone fumigation shifted the onset of the second phase from a PFD of about 60 μmol m−2 s−1 to about 30 μmol m−2 s−1. While the fertilizer concentration had no influence on this character, high fertilization supply of plants partially reduced
O3-induced damage. The light responses of Ft, Fm′ and NPQ observed in birch leaves grown in O3-free air indicate the existence of at least two different processes governing energy conversion of the photosynthetic apparatus
at PS II in the range of PFD 0–200 μmol photons m−2 s−1. The first phase was attributed to a rather slowly relaxing type of non-photochemical quenching, which, at least at low PFD,
is thought to be related to a state 1–2 transition. The further changes of the fluorescence parameters studied at higher PFD
might be explained by an increase of energy-dependent quenching, connected with the energization of the thylakoid membrane
and zeaxanthin synthesis. A major effect of ozone treatment was a lowering of PS II quantum yield. This reflects a reduction
of PS II electron transport and corresponds to the reduction of CO2-fixation observed in ozonated leaves.
Received: 24 September 1996 / Accepted: 27 January 1999 相似文献
14.
Summary Endogenous and exogenous volatile substances were analyzed during 30 days' incubation of four cultivars of thePrunus avium species grown in vitro on a proliferation medium. Cultivars Bigarreau Moreau and Bigarreau Burlat show photosynthetic capability
at 35 μmol·m−2·s−1; oxygen concentration slightly increased (22 to 24%), carbon dioxide was lowered to less than 300 μ·liter−1, and low ethylene (0.8 to 1.2·liter−1) accumulation was recorded. Quite different headspace evolution was observed during growth of cultivars Victoria and Casavecchia:
a large oxygen concentration decrease was accompanied by a sharp carbon dioxide increase (19%) and ethylene boost (4 to 5
μl·liter−1). The evolution of these gaseous metabolites has been correlated to photosynthetic incapability and respiratory stress responsible
for leaf yellowing and tissue softening observed when acetaldehyde and ethanol started to form in cultivars Victoria and Casavecchia.
Dry and fresh weight were measured, and no substantial difference was recorded among cultures with low and high photosynthetic
capability. Evidence is reported that different genotypes within the same species may follow different metabolic pathways. 相似文献
15.
Photosynthetic rates of green leaves (GL) and green flower petals (GFP) of the CAM plant Dendrobium cv. Burana Jade and their sensitivities to different growth irradiances were studied in shade-grown plants over a period
of 4 weeks. Maximal photosynthetic O2 evolution rates and CAM acidities [dawn/dusk fluctuations in titratable acidity] were higher in leaves exposed to intermediate
sunlight [a maximal photosynthetic photon flux density (PPFD) of 500–600 μmol m−2 s−1] than in leaves grown under full sunlight (a maximal PPFD of 1 000–1 200 μmol m−2 s−1) and shade (a maximal PPFD of 200–250 μmol m−2 s−1). However, these two parameters of GFP were highest in plants grown under the shade and lowest in full sun-grown plants.
Both GL and GFP of plants exposed to full sunlight had lower predawn Fv/Fm [dark adapted ratio of variable to maximal fluorescence (the maximal photosystem 2 yield without actinic irradiation)] than
those of shade-grown plants. When exposed to intermediate sunlight, however, there were no significant changes in predawn
Fv/Fm in GL whereas a significant decrease in predawn Fv/Fm was found in GFP of the same plant. GFP exposed to full sunlight exhibited a greater decrease in predawn Fv/Fm compared to those exposed to intermediate sunlight. The patterns of changes in total chlorophyll (Chl) content of GL and
GFP were similar to those of Fv/Fm. Although midday Fv/Fm fluctuated with prevailing irradiance, changes of midday Fv/Fm after exposure to different growth irradiances were similar to those of predawn Fv/Fm in both GL and GFP. The decreases in predawn and midday Fv/Fm were much more pronounced in GFP than in GL under full sunlight, indicating greater sensitivity in GFP to high irradiance
(HI). In the laboratory, electron transport rate and photochemical and non-photochemical quenching of Chl fluorescence were
also determined under different irradiances. All results indicated that GFP are more susceptible to HI than GL. Although the
GFP of Dendrobium cv. Burana Jade require a lower amount of radiant energy for photosynthesis and this plant is usually grown in the shade,
is not necessarily a shade plant. 相似文献
16.
Two cultivars (Katy and Erhuacao) of apricot (Prunus armeniaca L.) were evaluated under open-field and solar-heated greenhouse conditions in northwest China, to determine the effect of
photosynthetic photon flux density (PPFD), leaf temperature, and CO2 concentration on the net photosynthetic rate (P
N). In greenhouse, Katy registered 28.3 μmol m−2 s−1 for compensation irradiance and 823 μmol m−2 s−1 for saturation irradiance, which were 73 and 117 % of those required by Erhuacao, respectively. The optimum temperatures
for cvs. Katy and Erhuacao were 25 and 35 °C in open-field and 22 and 30 °C in greenhouse, respectively. At optimal temperatures,
P
N of the field-grown Katy was 16.5 μmol m−2 s−1, 21 % less than for a greenhouse-grown apricot. Both cultivars responded positively to CO2 concentrations below the CO2 saturation concentration, whereas Katy exhibited greater P
N (18 %) and higher carboxylation efficiency (91 %) than Erhuacao at optimal CO2 concentration. Both cultivars exhibited greater photosynthesis in solar-heated greenhouses than in open-field, but Katy performed
better than Erhuacao under greenhouse conditions. 相似文献
17.
In the southeast of the Qinghai-Tibetan Plateau of China, Mono Maple is a common species in reforestation processes. The paper mainly investigated the changes in morphological, photosynthetic and physiological responses of Mono Maple seedlings to UV-B radiation, nitrogen supply and their combination. The experimental design included two levels of UV-B treatments (ambient UV-B, 11.02 KJ m−2 day−1; enhanced UV-B, 14.33 KJ m−2 day−1) and two nitrogen levels (0; 20 g N m−2 a−1)—to determine whether the adverse effects of UV-B on plants are eased by nitrogen supply. Enhanced UV-B caused a marked decline in growth parameters, net photosynthetic rate, and photosynthetic pigments, whereas it induced an increase in reaction oxygen species (hydrogen peroxide accumulation and the rate of superoxide radical production) and malondialdehyde content. Enhance UV-B also induced an increase in antioxidant compounds of Mono Maple, such as UV-B absorbing compounds, proline content, and activities of antioxidant enzymes (peroxidase, superoxide dimutase and catalase). On the other hand, nitrogen supply caused an increase in some growth parameters, net photosynthetic rate, photosynthetic pigments and antioxidant compounds (peroxidase, proline content and UV-B absorbing compounds), and reduced the content of reaction oxygen species (H2O2 accumulation, the rate of O2− production) and malondialdehyde content under ambient UV-B. However, under enhanced UV-B, nitrogen supply inhibited some growth parameters, and increased H2O2 accumulation, the rate of O2− production and MDA content, though proline content, UV-B absorbing compounds and activities of POD and SOD increased. These results implied that enhanced UV-B brought harmful effects on Mono Maple seedlings and nitrogen supply made plants more sensitive to enhanced UV-B, though increased some antioxidant activity. 相似文献
18.
Winter wheat is a grass species widely planted in northern and central China, where the increase of aerosols, air pollutants
and population density are causing significant reduction in solar irradiance. In order to investigate the adaptation of winter
wheat (Triticum aestivum L., cv. Yangmai 13) to low irradiance conditions occurring in the downstream plain of the Yangtze River (China), plants were
subjected to four solar irradiance treatments (100%, 60%, 40%, and 20% of environmental incident solar irradiance). Significant
increases in chlorophyll (Chl) and xanthophyll (Xan) pigments, and decreases in Chl a/b and Xan/Chl ratios were observed in plants under low light. Light-response curves showed higher net photosynthetic rates
(P
N) in fully irradiated plants, that also showed a higher light-compensation point. Shaded plants maintained high values of
minimal fluorescence of dark-adapted state (Fo) and maximum quantum efficiency of PSII photochemistry (Fv/Fm) that assess a lower degree of photoinhibition under low light. Reduced irradiance caused decreases in effective quantum
yield of PSII photochemistry (ΦPSII), electron transport rate (ETR), and nonphotochemical quenching coefficient (qN), and the promotion of excitation pressure of PSII (1 − qP). The activities of the antioxidant enzymes superoxide dismutase and peroxidase were high under reduced light whereas no
light-dependent changes in catalase activity were observed. Thiobarbituric acid reactive species content and electrolyte leakage
decreased under shaded plants that showed a lower photooxidative damage. The results suggest that winter wheat cv. Yangmai
13 is able to maintain a high photosynthetic efficiency under reduced solar irradiance and acclimates well to shading tolerance.
The photosynthetic and antioxidant responses of winter wheat to low light levels could be important for winter wheat cultivation
and productivity. 相似文献
19.
Carlos Mesejo Salvatore Rosito Carmina Reig Amparo Martínez-Fuentes Manuel Agustí 《Journal of Plant Growth Regulation》2012,31(2):186-194
The aim of this study was to determine the effects of the synthetic auxin 3,5,6-trichloro-2-pirydiloxyacetic acid (3,5,6-TPA)
on photosynthetic activity, photosynthate transport to the fruit, and fruitlet abscission to further explain the physiological
basis of auxin-mediated citrus fruit thinning. Applying 15 mg l−1 3,5,6-TPA to trees during the fruit cell division stage significantly increased fruitlet abscission of Clementine mandarin.
On treated trees, abnormal foliar development and photosynthetic damage were observed at the same time as 3,5,6-TPA reduced
fruitlet growth rate. Briefly, treatment reduced chlorophyll and carotenoid concentrations and modified chlorophyll a fluorescence parameters, that is, reduced the quantum yield (ФPSII) of the noncyclic electron transport rate, diminished
the capacity to reduce the quinone pool (photochemical quenching; qp), and increased nonphotochemical quenching (q
N), thereby preventing the dissipation of excess excitation energy. In addition, the net photosynthetic flux (μmol CO2 m−2 s−1) and leaf photosynthate content decreased in treated trees. As a result, the 3,5,6-TPA treatment significantly reduced the
photosynthate accumulation in fruit from day 3 to day 8 after treatment, thus reducing fruitlet growth rate. Hence, treated
fruitlets significantly increased ethylene production and abscised. Twenty days after treatment, chlorophyll a fluorescence parameters and fruitlet growth rate were reestablished. Accordingly, the thinning effect of 3,5,6-TPA may be
due to a temporarily induced photosynthetic disorder that leads to reduction in photosynthate production and fruitlet uptake
that temporarily slows its growth, triggering ethylene production and fruitlet abscission. Afterward, the remaining treated
fruit overcame this effect, increased growth rate, and reached a larger size than control fruit. 相似文献
20.
A greenhouse experiment was conducted to assess whether exogenously applied 24-epibrassionlide (24-epiBL) could alleviate
the adverse effects of salt on wheat. Two hexaploid wheat (Triticum aestivum L.) cultivars, S-24 (salt tolerant) and MH-97 (moderately salt sensitive), were grown under control (0 mM NaCl in full strength
Hoagland’s nutrient solution) or saline conditions (150 mM of NaCl in full strength Hoagland’s nutrient solution). After 41 days
growth of wheat plants under saline conditions, 24-epiBL was applied as a foliar spray. Four levels of BR were used as 0 (water
spray), 0.0125, 0.025, and 0.0375 mg l−1. Application of 24-epiBL increased plant biomass and leaf area per plant of both cultivars under non-saline conditions. However,
under saline conditions, improvement in growth due to exogenous 24-epiBL was observed only in S-24. Photosynthetic rate was
reduced due to salt stress in both cultivars, but this inhibitory effect was ameliorated significantly by the exogenous application
of 24-epiBL. Exogenously applied 24-epiBL also enhanced the photosystem-II efficiency in both cultivars measured as F
v
/F
m
ratio. Although the activities of antioxidant enzymes, Superoxide dismutase (SOD), Peroxidase (POD) and Catalase (CAT) were
increased due to salt stress in both wheat cultivars, exogenously applied 24-epiBL had a varying effect on the antioxidant
system. The activity of SOD remained unaffected in both cultivars due to 24-epiBL application, but that of POD and CAT was
promoted in the salt stressed plants of cv. S-24 only. In conclusion, improvement in growth in both wheat cultivars due to
foliar applied 24-epiBL was found to be associated with 24-epiBL-induced enhancement in photosynthetic capacity. The 24-epiBL-induced
regulation of antioxidant enzymes or growth under saline conditions was cultivar specific. 相似文献