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1.
Analysis of antioxidant enzyme activity during germination of alfalfa under salt and drought stresses 总被引:2,自引:0,他引:2
Wen-Bin Wang Yun-Hee Kim Haeng-Soon Lee Ki-Yong Kim Xi-Ping Deng Sang-Soo Kwak 《Plant Physiology and Biochemistry》2009,47(7):570-577
To understand the adaptability of alfalfa (Medicago sativa L.) to environmental stresses, we analyzed the activity of several antioxidant enzymes, including superoxide dismutase (SOD), peroxidase (POD), ascorbate peroxidase (APX), and catalase (CAT), in alfalfa shoots and roots subjected to salt and drought stresses during germination. The germination rate of six alfalfa cultivars was comparatively studied under 200 mM NaCl or 35% PEG treatment. Alfalfa Xinmu No. 1 and Northstar varieties were selected as stress-tolerant and -sensitive cultivars, respectively, and were used for further characterization. After NaCl or PEG treatment, Xinmu No. 1 showed enhanced seedling growth, compared with Northstar. Xinmu No. 1 also exhibited low levels of hydrogen peroxide (H2O2) production and lipid peroxidation, compared with Northstar. In addition, Xinmu No. 1 showed higher enzymatic activity of SOD, APX, CAT, and POD in its shoots and roots than Northstar. These results seem to indicate that Xinmu No. 1 cultivar's tolerance to salt or drought stresses during germination is associated with enhanced activity of antioxidant enzymes. This study highlights the importance of antioxidant enzymes in the establishment of alfalfa seedlings under drought and salinity conditions typical of desertification. 相似文献
2.
S. A. Hosseini Boldaji R. A. Khavari-Nejad R. Hassan Sajedi H. Fahimi S. Saadatmand 《Acta Physiologiae Plantarum》2012,34(3):1177-1186
To understand alfalfa (Medicago sativa L.) reactions to osmotic stress, solutions with −0.5, −1 and −1.5 MPa osmotic potentials using PEG (Poly ethyleneglycol)
and distilled water as control were prepared. In a germination test, eleven alfalfa cultivar seeds were allowed to germinate
in these solutions. M. sativa cv. Yazdi and M. sativa cv. Gharayonje, selected as tolerant and sensitive cultivars, respectively, and were used for further studies. In all PEG
solutions, root and shoot dry weights decreased in both cultivars. Under different levels of osmotic stress, root to shoot
ratio increased significantly in Yazdi, whereas this parameter showed no significant differences in Gharayonje. Yazdi cultivar
also showed higher activities of SOD (Superoxide dismutase), APX (Ascorbate peroxidase), CAT (Catalase), POD (Peroxidase),
and higher reducing sugar contents of leaves in comparison with Gharayonje. These higher antioxidant activities help the tolerant
cultivar to decrease oxidative damages of osmotic stress to membrane lipids as compared with its sensitive counterpart. As
a result, electrolyte leakage and the amounts of MDA (Malondialdehyde), were higher in Gharayonje. This study highlights the
importance of enzymatic and non-enzymatic antioxidant systems in scavenging reactive oxygen species which is caused by osmotic
stress. It is seems that antioxidant systems are more active in tolerant cultivars than those of sensitive ones. 相似文献
3.
Characteristics of chlorophyll fluorescence and antioxidative system in super-hybrid rice and its parental cultivars under chilling stress 总被引:1,自引:0,他引:1
Y. H. Zhang L. J. Chen J. L. He L. S. Qian L. Q. Wu R. F. Wang 《Biologia Plantarum》2010,54(1):164-168
Characteristics of chlorophyll fluorescence and antioxidative system were investigated in rice (Oryza sativa L.) super-hybrid Liangyoupeijiu (LYPJ), maternal cultivar Peiai64s, and paternal cultivar indica rice 9311 under chilling
stress. During 6-d chilling treatment, chlorophyll content of all three genotypes was gradually declined. However, the decrease
in photosystem 2 (PS 2) maximum photochemical efficiency (Fv/Fm) and quantum yield of PS 2 (ΦPS2) was less expressive in LYPJ than in parental cultivars The electrolyte leakage and malondialdehyde content in all cultivars
increased after chilling treatment, but LYPJ exhibited the least increasing tendency. Activities of superoxide dismutase (SOD),
ascorbate peroxidase (APX) and glutathione reductase (GR) were higher in LYPJ than in parental cultivars. The results demonstrated
that tolerance to chilling stress in LYPJ might be adopted mostly from its maternal cultivar. 相似文献
4.
Genetic basis of heterosis explored by simple sequence repeat markers in a random-mated maize population 总被引:8,自引:0,他引:8
Funatsuki H Kurosaki H Murakami T Matsuba S Kawaguchi K Yumoto S Sato Y 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》2003,107(3):494-502
We investigated the isozyme profiles of antioxidant enzymes in cultivars and lines with different seed productivity in cool climate conditions as a step towards understanding the physiological and genetical mechanisms underlying chilling tolerance in soybean. While no difference in superoxide dismutase, or catalase isozyme profiles was observed among the cultivars and lines tested, we found polymorphism in the ascorbate peroxidase isozyme profile; there were two types, with or without a cytosolic isoform (APX1). The cultivars and lines lacking APX1 proved more tolerant to chilling temperatures, as evaluated by yielding ability. The genotype-dependent deficiency of APX1 was consistent in plants and tissues under various oxidative stress conditions including the exposure to low-temperatures. In addition, the genetic analysis of progeny derived from crossing between cultivars differing in the isozyme profile indicated that the APX1 deficiency is controlled by a single recessive gene (apx1), and is inherited independently of the genes that have previously been identified for their association with chilling tolerance. Molecular and linkage analyses suggested that the variant gene of the APX1-absent genotype coding for a cytosolic APX, which contained a single nucleotide substitution and a single nucleotide deletion in the coding region, is responsible for the genotype-dependent deficiency of APX1. The association of APX1 deficiency with chilling tolerance is discussed in detail. 相似文献
5.
The effect of foliar pretreatment by hydrogen peroxide (H2O2) at low concentrations of 0, 5, 10, and 15 mM on the chilling tolerance of two Zoysia cultivars, manilagrass (Zoysia matrella) and mascarenegrass (Zoysia tenuifolia), was studied. The optimal concentration for H2O2 pretreatment was 10 mM, as demonstrated by the lowest malondialdehyde (MDA) content and electrolyte leakage (EL) levels and
higher protein content under chilling stress (7°C/2°C, day/night). Prior to initiation of chilling, exogenous 10 mM H2O2 significantly increased catalase (CAT), ascorbate peroxidase (APX), glutathione-dependent peroxidases (GPX), and glutathione-S-transferase (GST) activities in manilagrass, and guaiacol peroxidase (POD), APX, and glutathione reductase (GR) activities
in mascarenegrass, suggesting that H2O2 may act as a signaling molecule, inducing protective metabolic responses against further oxidative damage due to chilling.
Under further stress, optimal pretreatments alleviated the increase of H2O2 level and the decrease of turfgrass quality, and improved CAT, POD, APX, GR, and GPX activities, with especially significant
enhancement of APX and GPX activities from the initiation to end of chilling. These antioxidative enzymes were likely the
important factors for acquisition of tolerance to chilling stress in the two Zoysia cultivars. Our results showed that pretreatment with H2O2 at appropriate concentration may improve the tolerance of warm-season Zoysia grasses to chilling stress, and that manilagrass had better tolerance to chilling, as evaluated by lower MDA and EL, and
better turfgrass quality, regardless of the pretreatment applied. 相似文献
6.
Postharvest chilling induces oxidative stress response in the dwarf tomato cultivar Micro-Tom 总被引:1,自引:0,他引:1
Oxidative stress is involved in the response of Lycopersicon esculentum fruits (cultivar Micro-Tom) to chilling. Changes in activated oxygen scavenging enzymes, superoxide dismutase (SOD, EC 1.15.1.1), catalase (CAT, EC 1.11.1.6), ascorbate peroxidase (APX, EC 1.11.1.11), and glutathione reductase (GR, EC 1.6.4.2) were examined during ripening after postharvest chilling. Also, lipid peroxidation, respiration, and pigment contents were determined. These parameters were affected by chilling, especially the lycopene content and the respiration rate that showed a high value when the fruits were transferred to higher temperatures. CAT activity increased the day after the fruits were re-warmed, while the activity of GR was higher in the chilled than in the non-chilled green fruits. Lipid peroxidation was more evident at the 'pre-chilled' yellow and red fruits. APX and SOD were not affected by previous chilling in ripening fruits. These results indicate that oxidative stress is generated by conservation at 4°C. The antioxidant response of tomato fruit could be mediated by CAT and GR but not by SOD or APX. Moreover, CAT seemed to respond to the increase in the respiration rate. 相似文献
7.
低温弱光胁迫对野生大豆和大豆栽培种光系统功能的影响 总被引:13,自引:0,他引:13
以野生大豆和栽培大豆为材料,通过同时测定大豆叶片的叶绿素荧光快速诱导动力学曲线和对820nm光的吸收曲线,以及测定超氧化物歧化酶(SOD)和抗坏血酸过氧化物酶(APX)的活性,分析了低温弱光胁迫及常温弱光恢复下这2种大豆光系统Ⅱ(PSⅡ)和光系统Ⅰ(PSI)功能的变化。结果表明,低温弱光胁迫对这2种大豆的PSI和PSⅡ的功能都造成伤害;在低温弱光胁迫下,维持较高的SOD和APX活性和维持PSI和PSⅡ的协调性是野生大豆比栽培大豆耐低温的一个重要原因。 相似文献
8.
Differential responses of antioxidative system to chilling and drought in four rice cultivars differing in sensitivity 总被引:9,自引:0,他引:9
Responses of antioxidative defense systems to chilling and drought stresses were comparatively studied in four cultivars of rice (Oryza sativa L.) differing in sensitivity, two of them (Xiangnuo no. 1 and Zimanuo) are tolerant to chilling but sensitive to drought and the other two (Xiangzhongxian no. 2 and IR50) are tolerant to drought but sensitive to chilling. The seedlings of rice were transferred into growth chamber for 5 d at 8 degrees C as chilling treatment, or at 28 degrees C as control, or at 28 degrees C but cultured in 23% PEG-6000 solution as drought stress treatment. Under drought stress the elevated levels of electrolyte leakage, contents of H(2)O(2) and total thiobarbituric acid-reacting substances (TBARS) in Xiangzhongxian no. 2 and IR50 are lower than those in Xiangnuo no. 1 and Zimanuo. On the contrary, Xiangnuo no. 1 and Zimanuo have much lower level of electrolyte leakage, H(2)O(2) and TBARS than Xiangzhongxian no. 2 and IR50 under chilling stress. Activities of antioxidant enzymes (superoxide dismutase (SOD), catalase, and ascorbate-peroxidase (APX)) and contents of antioxidants (ascorbaic acid and reduced glutathione) were measured during the stress treatments. All of them were enhanced greatly until 3 d after drought stress in the two drought-tolerant cultivars, or after chilling stress in the two chilling-tolerant cultivars. They all were decreased at 5 d after stress treatments. On the other hand, activities of antioxidant enzymes and contents of antioxidants were decreased greatly in the drought-sensitive cultivars after drought stress, or in the chilling-sensitive cultivars after chilling stress. The results indicated that tolerance to drought or chilling in rice is well associated with the enhanced capacity of antioxidative system under drought or chilling condition, and that the sensitivity of rice to drought or chilling is linear correlated to the decreased capacity of antioxidative system. 相似文献
9.
Effect of chilling on antioxidant enzymes and DPPH-radical scavenging activity of high- and low-vigour cucumber seedling radicles 总被引:10,自引:0,他引:10
The chilling tolerance of cucumber seedling radicles was influenced by their relative levels of vigour. Radicles of high‐vigour seedlings grew to 20 mm in length in 36 h at 25 °C, whereas it took 60 h for low‐vigour seedling radicles to reach that length. Chilling at 2·5 °C for 48 h inhibited the subsequent growth of high‐ and low‐vigour seedlings by 39 and 68%, respectively. The 2,3,5‐triphenyltetrazolium chloride (TTC) viability index, and α,α‐diphenyl‐β‐picrylhydrazyl (DPPH)‐radical scavenging activity were higher in high than low‐vigour radicles. Higher ascorbate peroxidase (APX) and catalase (CAT) enzyme activity, DPPH‐radical scavenging activity, and recovery of CAT activity after chilling in high‐vigour radicles corresponded with their higher level of chilling tolerance in comparison with low‐vigour radicles. In contrast, elevated levels of superoxide dismutase, glutathione reductase and guaiacol peroxidase appear to be correlated with chilling injury since they only showed substantial increases in activity in the more chilling‐sensitive low‐vigour radicles after chilling. Manipulation of APX, CAT, and/or DPPH activity could produce plants with superior and persistent chilling tolerance. 相似文献
10.
Alfalfa (Medicago sativa L.), when exposed to abiotic stress such as salinity, suffers significant losses in yield and
productivity. The present study evaluated the salinity tolerance of 12 alfalfa cultivars in vitro using five concentrations of sodium chloride (NaCl), ranging from 0 to 250 mmol L−1
. The results obtained in the current study
revealed that the Saudi cultivars, Kasimi and Hassawi, and the German cultivar (Berlin) had the highest salinity
tolerance in terms of germination percentage (GP), corrected germination rate index (CGRI), days to reach 50%
germination (GT50), and ability to form cotyledonary and true leaves. Under mmol L−1 NaCl, the Saudi cultivar
Kasimi cultivar showed GP, CGRI, and GT50 of 55.20%, 123.15, and 3.77 days, respectively. Similarly, the German
cultivar (Berlin) showed GP, CGRI, and GT50 of 50.06%, 86.61, and 5.17 days, respectively. These findings might
reveal a pivotal aspect in salt tolerance in alfalfa. Our results will help to select salt-tolerant alfalfa cultivars that
could thrive in arid and semi-arid areas with salinity problems. 相似文献
11.
12.
U. Celikkol Akcay O. Ercan M. Kavas L. Yildiz C. Yilmaz H. A. Oktem M. Yucel 《Plant Growth Regulation》2010,61(1):21-28
Two cultivars of peanut (Arachis
hypogaea L.) which were designated as resistant (Florispan) and sensitive (Gazipasa) according to their growth retardation under drought
stress conditions were compared for their oxidative damage and antioxidant responses. Sixteen days-old peanut seedlings were
subjected to PEG-6000 solutions of two different osmotic potentials; −0.4 and −0.8 MPa, and various growth parameters, photosystem
II activity, changes in malondialdehyde (MDA), hydrogen peroxide (H2O2) and proline levels, activities of ascorbate peroxidase (APX), catalase (CAT), peroxidase (POX) and gluthatione reductase
(GR) enzymes were determined. Both cultivars exhibited water deficit at −0.8 MPa osmotic potential of PEG-6000 and H2O2 levels significantly increased during exposure to −0.4 MPa osmotic potential. However, H2O2 levels were under control in both cultivars at exposure to −0.8 MPa osmotic potential. Significant proline accumulation was
observed in the tissues of cv. Florispan at −0.8 MPa osmotic potential, whereas proline accumulation did not appear to be
an essential part of the protection mechanism against drought in cv. Gazipasa. No significant variation in chlorophyll fluorescence
values were detected in neither of the cultivars. Enzyme activity measurements revealed that Gazipasa copes well with lesser
magnitudes of drought stress by increasing the activity of mainly APX, and during harsh stress conditions, only APX maintains
its activity in the tissues. In cultivar Florispan, GR activity appears to take role in lesser magnitudes of drought stress,
whereas CAT and APX activities appear to be very crucial antioxidative defenses during intense stress conditions. The results
indicate that, the level of proline and activities of the enzymes CAT and APX are important mechanisms for the maintenance
of drought tolerance in peanut plants. 相似文献
13.
In order to investigate the function of chloroplast ascorbate peroxidase under temperature stress, the thylakoid-bound ascorbate
peroxidase gene from tomato leaf (TtAPX) was introduced into tobacco. Transformants were selected for their ability to grow on medium containing kanamycin. RNA gel
blot analysis confirmed that TtAPX in tomato was induced by chilling or heat stress. Over-expression of TtAPX in tobacco improved seed germination under temperature stress. Two transgenic tobacco lines showed higher ascorbate peroxidase
activity, accumulated less hydrogen peroxide and malondialdehyde than wild type plants under stress condition. The photochemical
efficiency of photosystem 2 in the transgenic lines was distinctly higher than that of wild type plants under chilling and
heat stresses. Results indicated that the over-expression of TtAPX enhanced tolerance to temperature stress in transgenic tobacco plants. 相似文献
14.
Soon Lim Yun-Hee Kim Sun-Hyung Kim Suk-Yoon Kwon Haeng-Soon Lee Jin-Seog Kim Kwang-Yun Cho Kee-Yoeup Paek Sang-Soo Kwak 《Molecular breeding : new strategies in plant improvement》2007,19(3):227-239
Oxidative stress is one of the major factors causing injury to plants exposed to environmental stress. Transgenic sweetpotato
[Ipomoea batatas (L.) Lam. cv. Yulmi] plants with an enhanced tolerance to multiple environmental stresses were developed by expressing the
genes of both CuZn superoxide dismutase (CuZnSOD) and ascorbate peroxidase (APX) under the control of an oxidative stress-inducible
SWPA2 promoter in the chloroplasts of sweetpotato plants (referred to as SSA plants). SSA plants were successfully generated by
the particle bombardment method and confirmed by PCR analysis. When leaf discs of SSA plants were subjected to 5 μM methyl viologen (MV), they showed approximately 45% less damage than non-transformed (NT) plants. When 200 μM MV was sprayed onto the whole plants, SSA plants showed a significant reduction in visible damage compared to leaves of NT
plants, which were almost destroyed. The expression of the introduced CuZnSOD and APX genes in leaves of SSA plants following
MV treatment was significantly induced, thereby reflecting increased levels of SOD and APX in the chloroplasts. APX activity
in chloroplast fractions isolated from SSA plants was approximately 15-fold higher than that in their counterparts from NT
plants. SSA plants treated with a chilling stress consisting of 4°C for 24 h exhibited an attenuated decrease in photosynthetic
activity (Fv/Fm) relative to NT plants; furthermore, after 12 h of recovery following chilling, the Fv/Fm of SSA plants almost
fully recovered to the initial levels, whereas NT plants remained at a lower level of Fv/Fm activity. These results suggest
that SSA plants would be a useful plant crop for commercial cultivation under unfavorable growth conditions. In addition,
the manipulation of the antioxidative mechanism in chloroplasts can be applied to the development of various other transgenic
crops with an increased tolerance to multiple environmental stresses. 相似文献
15.
Over-expression of chloroplastic glycerol-3-phosphate acyltransferase gene (LeGPAT) increased unsaturated fatty acid contents in phosphatidylglycerol (PG) of thylakoid membrane in tomato. The effect of this
increase on the xanthophyll cycle and chloroplast antioxidant enzymes was examined by comparing wild type (WT) tomato with
the transgenic (TG) lines at chilling temperature (4 °C) under low irradiance (100 μmol m−2 s−1). Net photosynthetic rate and the maximal photochemical efficiency of photosystem (PS) 2 (Fv/Fm) in TG plants decreased more slowly during chilling stress and Fv/Fm recovered faster than that in WT plants under optimal conditions. The oxidizable P700 in both WT and TG plants decreased
during chilling stress under low irradiance, but recovered faster in TG plants than in the WT ones. During chilling stress,
non-photochemical quenching (NPQ) and the de-epoxidized ratio of xanthophyll cycle in WT plants were lower than those of TG
tomatoes. The higher activities of superoxide dismutase (SOD) and ascorbate peroxidase (APX) in TG plants resulted in the
reduction of O2
−· and H2O2 contents during chilling stress. Hence the increase in content of unsaturated fatty acids in PG by the over-expression of
LeGPAT could alleviate photoinhibition of PS2 and PS1 by improving the de-epoxidized ratio of xanthophyll cycle and activities of
SOD and APX in chloroplast. 相似文献
16.
Enhanced chilling tolerance at the booting stage in rice by transgenic overexpression of the ascorbate peroxidase gene, OsAPXa 总被引:3,自引:0,他引:3
Low temperatures during the booting stage reduce rice yields by causing cold-induced male sterility. To determine whether
antioxidant capacity affects the ability of rice plants to withstand chilling at the booting stage, we produced transgenic
rice plants that overexpress OsAPXa and have increased APX activity. The effect of increased APX activity on the levels of H2O2 and lipid peroxidation were determined by measuring H2O2 levels and malondialdehyde (MDA) contents in spikelets during cold treatments at the booting stage. The levels of H2O2 and the MDA content increased by 1.5-fold and twofold, respectively in WT plants subjected to a 12°C treatment for 6 days.
In contrast, transgenic lines showed small changes in H2O2 levels and MDA content under cold stress, and H2O2 levels and MDA content were significantly lower than in WT plants. APX activity showed negative correlations with levels
of H2O2 and MDA content, which increased during cold treatment. Cold tolerance at the booting stage in transgenic lines and WT plants
was evaluated. Spikelet fertility was significantly higher in transgenic lines than in WT plants after a 12°C treatment for
6 days. These results indicate that higher APX activity enhances H2O2-scavenging capacity and protects spikelets from lipid peroxidation, thereby increasing spikelet fertility under cold stress. 相似文献
17.
低温锻炼后桑树幼苗光合作用和抗氧化酶对冷胁迫的响应 总被引:12,自引:0,他引:12
以桑树品种“秋雨”为试验材料,研究了桑树幼苗在低温锻炼、冷胁迫和常温恢复期间的光合作用和抗氧化酶活性的变化.结果表明: 12 ℃3 d低温锻炼明显提高了桑树幼苗的抗冷性.3 ℃3 d冷胁迫下,12 ℃3 d低温锻炼后的桑树幼苗叶片净光合速率(Pn)、气孔导度(Gs)和PSⅡ 最大光化学效率(Fv/Fm)明显高于对照(未经低温锻炼)处理的桑树幼苗,而且其在常温下的恢复也较对照桑树幼苗迅速.在12 ℃ 3 d低温锻炼和3 ℃ 3 d冷胁迫期间,桑树幼苗叶片脯氨酸和可溶性糖含量明显增加,而经低温锻炼的桑树幼苗叶片丙二醛(MDA)含量明显低于未经低温锻炼的桑树幼苗,经低温锻炼的桑树幼苗叶片抗坏血酸过氧化物酶(APX)活性则明显高于未经低温锻炼的桑树幼苗.说明渗透调节物质含量增加和APX活性提高在低温锻炼诱导桑树幼苗的抗冷性上发挥着重要的作用. 相似文献
18.
Parviz Malekzadeh Jalil Khara Reza Heydari 《Physiology and Molecular Biology of Plants》2014,20(1):133-137
Low temperature during germination and early seedling growth is one of the most significant limiting factors in the productivity of plants. Tomato seedling germination is sensitive to chilling stress. Gamma-aminobutyric acid (GABA), as a non-protein amino acid, involved in various stress tolerances in plants. In this study, 5-day old tomato seedlings were exposed to chilling stress (2 ± 0.05 °C for 48 h) and then the effects of 0, 100, 250, 500 and 750 μmolL−1 concentrations of GABA on electrolyte leakage, proline and malondialdehyde (MDA) content were investigated. The resultS showed that the antioxidant enzyme activity, electrolyte leakage, MDA and proline content were significantly reduced by GABA treatments. However under chilling stress seedlings treated with GABA exhibited significantly higher sugar and proline contents as compared to un-treated seedlings. These results suggest that GABA treatment protects tomato seedlings from chilling stress by enhancing some antioxidant enzymes activity and reducing MDA content which results in maintaining membrane integrity. 相似文献
19.
The system modulating ROS content in germinating seeds of two Brazilian savanna tree species exposed to As and Zn 总被引:1,自引:0,他引:1
M. P. Gomes M. M. L. C. Carneiro C. O. G. Nogueira A. M. Soares Q. S. Garcia 《Acta Physiologiae Plantarum》2013,35(4):1011-1022
The effects of increasing arsenic (0, 10, 50, 100 mg L?1) and zinc (0, 50, 80, 120, 200 mg L?1) doses on germination and oxidative stress markers (H2O2, MDA, SOD, CAT, APX, and GR) were examined in two Brazilian savanna tree species (Anadenanthera peregrina and Myracrodruon urundeuva) commonly used to remediate contaminated soils. The deleterious effects of As and Zn on seed germination were due to As- and Zn-induced H2O2 accumulation and inhibition of APX and GR activities, which lead to oxidative damage by lipid peroxidation. SOD and CAT did not show any As- and Zn-induced inhibition of their activities as was seen with APX and GR. We investigated the close relationships between seed germination success under As and Zn stress in terms of GR and, especially, APX activities. Increased germination of A. peregrina seeds exposed to 50 mg L?1 of Zn was related to increased APX activity, and germination in the presence of As (10 mg L?1) was observed only in M. urundeuva seeds that demonstrated increased APX activity. All the treatments for both species in which germination decreased or was inhibited showed decreases in APX activity. A. peregrina seeds showed higher Zn-tolerance than M. urundeuva, while the reverse was observed with arsenic up to exposures of 10 mg L?1. 相似文献
20.
The Susceptibility of Cucumber and Sweet Pepper to Chilling Under Low Irradiance is Related to Energy Dissipation and Water-Water Cycle 总被引:23,自引:4,他引:19
The photoprotection of energy dissipation and water-water cycle were investigated by comparing chilling sensitivity of photosystems
2 (PS2) and 1 (PS1) in two chilling-sensitive plants, cucumber and sweet pepper, upon exposure to 4 °C under low irradiance
(100 μmol m−2 s−1) for 6 h. During chilling stress, the maximum photochemical efficiency of PS2 (Fv/Fm) decreased only slightly in both plants, but the oxidisable P700 decreased markedly, which indicated that PS1 was more sensitive
to chilling treatment under low irradiance than PS2. Sweet pepper leaves had lower Fv/Fm, higher non-photochemical quenching (NPQ), and higher oxidisable P700 during chilling stress. Activity of superoxide dismutase
(SOD) and ascorbate peroxidase (APX) in cucumber leaves was higher, but APX activity decreased apparently compared to that
at room temperature. The productions of active oxygen species (H2O2, O2
−) increased in both plants, faster in cucumber leaves than in sweet pepper leaves. In sweet pepper leaves, a stronger de-epoxidation
of the xanthophyll cycle pigments, a higher NPQ could act as a major protective mechanism to reduce the formation of active
oxygen species during stress. Thus sensitivity of both plants to chilling under low irradiance was dominated by the protective
mechanisms between PS1 and PS2, especially the energy dissipation and the water-water cycle.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献