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1.
Among plant species rice (Oryza sativa L.) leaves can be characterised with a very high level of salicylic acid content; however, its exact role is still poorly understood. In the present work, rice genotypes with different levels of drought tolerance have been subjected to PEG‐induced drought or cold stress at 10 °C in order to find relationship between the salicylic acid metabolism and the level of stress tolerance; and between the salicylic acid level and other protective mechanisms. Although the drought‐sensitive genotypes usually contained slightly higher amount of salicylic acid than the tolerant ones, there was no strong correlation between the salicylic acid contents and the degree of drought tolerance. Because the expression pattern of the chorismate synthase and isochorismate synthase genes did not correlate with the level of salicylic acid, but there was a correlation between the levels of salicylic acid and ortho‐hydroxy‐cinnamic, it is assumed that the salicylic acid synthesis via ortho‐hydroxy‐cinnamic acid may play a more decisive role than the chorismate–isochorismate–salicylic acid pathway in rice. While the activity of the glutathione reductase enzyme did not show correlation with drought tolerance, the glutathione S‐transferase activities were usually higher in the leaves of the drought‐tolerant varieties than in the sensitive ones. The salicylic acid contents in the leaves were not substantially affected by the applied stress conditions; however, other stress‐related compounds polyamines showed marked, stress‐specific responses. Correlation data suggest that there is no direct link between the abiotic stress‐induced polyamine changes and the salicylic acid metabolism in rice.  相似文献   

2.
To find a connection between polyamines and various protective effectors involved in the development of cold tolerance, eight different cereal genotypes, including wheat, barley and oat species, were investigated during the acclimation phase to low temperature. Exposure to low temperature induced different changes in the levels of polyamines, and other signalling molecules, such as salicylic acid and abscisic acid, and of other protective compounds, namely flavonols, sugars and antioxidant enzyme activity, and in the lipid composition of certain membrane factions. The most remarkable differences were observed in the oat varieties compared to the other cereal genotypes, which was manifested in the lack of spermidine accumulation and of decrease in trans‐Δ3‐hexadecanoic acid content, in lower initial and not cold‐inducible abscisic acid content and guaiacol peroxidase activity after cold treatment. Correlation analysis revealed that spermidine shows strong positive relationship with flavonols, abscisic acid and ascorbate peroxidase, while was in negative relationship with trans‐Δ3‐hexadecanoic acid. These results suggest that spermidine may have a crucial role in the cold acclimation signalling processes in cereals.  相似文献   

3.
The optimum temperature for maize germination is between 25 and 28 °C. Poor and erratic germination at suboptimal temperature is the most important hindrance in its early sowing. This study was conducted to induce chilling tolerance in hybrid maize (Zea mays L.) by seed priming with salicylic acid (SA) and to unravel the background biochemical basis. For seed priming, maize hybrid (Hycorn 8288) seeds were soaked in 50, 100 and 150 ppm (mg l?1) aerated solutions of SA for 24 h and were dried back. Treated and untreated seeds were sown at 27 °C (optimal temperature) and at 15 °C (chilling stress) under controlled conditions. Performance of maize seedlings was hampered under chilling stress. But seed priming with SA improved the seedling emergence, root and shoot length, seedling fresh and dry weights, and leaf and root score considerably compared with control both at optimal and chilling temperatures. However, priming in 50 mg l?1 SA solution was more effective, followed by priming in 100 mg l?1 SA solution. Seed priming with SA improved the chilling tolerance in hybrid maize mainly by the activation of antioxidants (including catalase, superoxide dismutase and ascorbate peroxidase). Moreover, maintenance of high tissue water contents and reduced membrane permeability also contributed towards chilling tolerance.  相似文献   

4.
There is a lack of knowledge about factors contributing to the chilling‐induced alleviatory effects on growth of plants under salt stress. Thus, the primary objective of the study was to determine whether chilling‐induced changes in endogenous hormones, ionic partitioning within shoots and roots and/or gaseous exchange characteristics is involved in salt tolerance of two genetically diverses of wheat crops. For this purpose, the seeds of two spring wheat (Triticum aestivum) cultivars, MH‐97 (salt intolerant) and Inqlab‐91 (salt tolerant) were chilled at 3°C for 2 weeks. The chilled, hydroprimed and non‐primed (control) seeds of the two wheat cultivars were sown in both Petri dishes in a growth room and in the field after treatment with 15 dS m?1 NaCl salinity. Chilling was very effective in increasing germination rate and subsequent growth when compared with hydropriming and control under salt stress. Results from field experiments clearly indicated the efficacy of chilling over hydropriming in improving shoot dry biomass and grain yield in either cultivar, particularly under salt stress. This increase in growth and yield was related to increased net photosynthetic rate, greater potential to uptake and accumulate the beneficial mineral elements (K+ and Ca2+) in the roots and reduced uptake and accumulation of toxic mineral element (Na+) in the shoots of both wheat cultivars when grown under salt stress. Salt‐stressed plants of both wheat cultivars raised from chilled seed had greater concentrations of indoleacetic acid, abscisic acid, salicylic acid and spermine when compared with hydropriming and control. Therefore, induction of salt tolerance by pre‐sowing chilling treatment in wheat could be attributed to its beneficial effects on ionic homeostasis and hormonal balance. The results presented are also helpful to understand the chilling‐induced cross adaptation of plants in natural environments. Moreover, efficacy of pre‐sowing chilling treatment over hydropriming suggested its commercial utilization as a low risk priming treatment for better wheat crop production under stressful environments.  相似文献   

5.
To improve the abiotic stress tolerance of maize (Zea mays L.), doubled haploid (DH) plants were produced by in vitro selection of microspores exposed to tert‐butyl hydroperoxide (t‐BuOOH) as a powerful prooxidant This study investigated the tolerance of the progenies of t‐BuOOH‐selected DH lines to oxidative stress, cold and drought in controlled environment pot experiments by analyses of photosynthetic electron transport and CO2 assimilation processes, chlorophyll bleaching and lipid peroxidation of leaves. Our results demonstrated that the t‐BuOOH‐selected DH plants exhibited enhanced tolerance not only to oxidative stress‐induced by t‐BuOOH but also to cold and drought stresses. In addition, they showed elevated activities of antioxidant enzymes such as superoxide dismutase, ascorbate peroxidase, catalase, glutathione reductase and glutathione S‐transferase when compared with the DH lines derived from microspores that were not exposed to t‐BuOOH and to the original hybrid plants. The results suggest that the simultaneous up‐regulation of several antioxidant enzymes may contribute to the oxidative and cold stress tolerance of the t‐BuOOH‐selected DH lines, and that the in vitro microspore selection represents a potential way to improve abiotic stress tolerance in maize.  相似文献   

6.
Recent studies on chilling tolerance mechanisms in maize revealed a significant positive correlation between genotypic chilling tolerance and chilling‐induced accumulation of the stress hormone abscisic acid (ABA) under controlled growth chamber conditions. Based on this and other results, the hypothesis was developed that chilling tolerance in maize is related to the ability to accumulate large amounts of ABA rapidly, as a protection against chilling injury. The objective of the present study was to test this hypothesis under field conditions during natural cold weather periods in spring, which often cause severe chilling injury in maize fields. In two experiments at two locations in Europe with contrasting climates, eight maize genotypes with different genotypic chilling tolerance were cultivated in spring in the field according to agronomic practice for maize. Before and at the end of cold weather periods, ABA levels and water contents were determined in the third leaves. It was found that chilling‐tolerant genotypes accumulated higher amounts of ABA during the chilling period than chilling‐sensitive genotypes. A significant positive correlation between chilling tolerance and the levels of ABA in the leaves was found. These results support the above‐mentioned hypothesis. In contrast to earlier studies performed under growth chamber conditions, the water content in chilled leaves was mostly higher than in non‐chilled leaves. The increase in ABA is therefore not attributable to chilling‐induced water deficit, but probably to the low temperature itself.  相似文献   

7.
Two chilling‐tolerant genotypes, that is, weedy rice WR03‐45 and cultivated rice Lijiangxintuanheigu and two chilling‐sensitive genotypes, that is, weedy rice WR03‐26 and cultivated rice Xiuzinuo were used in this study to investigate the effects of exogenous abscisic acid (ABA) on protection against chilling damage as well as on changes in physiological features. The results showed that under chilling stress the increased levels of superoxide radical (), hydrogen peroxide (H2O2) and malondialdehyde (MDA) in WR03‐45 and Lijiangxintuanheigu were lower than those in WR03‐26 and Xiuzinuo. Activities of antioxidant enzymes (superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APX), glutathione reductase (GR)) and non‐enzymatic antioxidants (ascorbate acid (AsA) and reduced glutathione (GSH)) were enhanced in WR03‐45 and Lijiangxintuanheigu, whereas they were decreased significantly in WR03‐26 and Xiuzinuo. Application of exogenous ABA reduced the chilling damage in the four genotypes. The pre‐treatment with ABA decreased the levels of , H2O2 and MDA caused by chilling stress in the four genotypes through increasing the activities of SOD, CAT, APX, GR and the contents of AsA and GSH in the four genotypes under chilling stress. Moreover, pre‐treatment with Fluridone, the ABA biosynthesis inhibitor, prohibited the effects of ABA through enhancing the oxidative damages and suppressing the antioxidant defence systems under chilling stress. The results indicate the mechanism for rice with chilling tolerance is to enhance the capacity of antioxidant defence systems under chilling stress. Furthermore, ABA plays important roles in the tolerance of rice against chilling stress for it could induce the capacity of whole antioxidant defence systems including enzymatic and non‐enzymatic constitutions under chilling stress.  相似文献   

8.
The objective of this study was to investigate the effect of the different concentrations of the seed film coating salicylic acid on the cold tolerance of cotton seedlings using the sand culture method. The physiological response of cell membrane permeability, protective enzyme activity and osmotic adjustment of cotton seedling were measured before and after at low temperature stress and at normal temperature. The results showed that 1-10 mmol·L－1 of seed film coating with salicylic acid seed coating treatment could effectively alleviate damage to cotton seedlings at low temperature, and the accumulation of the relative electrical conductivity and malondialdehyde were reduced on cotton seedlings. The activity of superoxide dismutase, peroxidase, catalase, and soluble protein, soluble sugar and proline contents increased sharply. These results indicate that film coating with salicylic acid can alleviate the effects of low temperature stress on seedling growth inhibition and improve the cotton seedlings by providing chilling tolerance, and the optimum treatment concentration salicylic acid is 5 mmol·L－1.  相似文献   

9.
脱落酸对低温胁迫下玉米幼苗生长和光合特性的影响   总被引：1，自引：0，他引：1  
田礼欣  杨晔  左师宇  刘旋  魏湜  孙磊  李晶 《作物杂志》2018,34(6):76-152
脱落酸（ABA）是作物生产中广泛应用的一种植物激素。探究ABA对低温胁迫下玉米幼苗光合特性的影响,为阐明低温胁迫下玉米幼苗叶片光合结构的防御保护机制提供理论依据。以玉米品种“久龙5号”为试验材料,采用盆栽试验,探讨了低温胁迫0、2、4、6、8d下不同浓度脱落酸对玉米幼苗生长及光合特性的影响。结果表明,低温胁迫显著抑制玉米幼苗的正常生长,导致SPAD值下降,叶片净光合速率（Pn）、蒸腾速率（Tr）、气孔导度（Gs）、PSⅡ光化学最大效率（Fv/Fm）和潜在光化学效率（Fv/Fo）水平下降,初始荧光（Fo）显著升高。外源喷施适当浓度的ABA能够显著缓解由低温胁迫导致的玉米叶片Pn、Tr和Gs下降幅度,提高Fv/Fm和Fv/Fo,降低Fo水平。由此可见,外源施加适当浓度的ABA能提高幼苗叶片的光合能力,提高PSⅡ反应中心活性,促进物质积累,提高玉米幼苗的耐冷性。同时,外源施加ABA存在一定的浓度效应,即“低促高抑”。本研究所设计浓度范围中15mg/L ABA浓度对光合抑制缓解效果最显著。  相似文献   

10.
The effect of salt stress on salicylic acid (SA) synthesis was investigated parallel with the induction of antioxidant enzymes in young maize plants. Two-week-old maize plants grown in hydroponic solution were treated with 50 or 100 m m NaCl for 7 days. Antioxidant enzyme activities, and the SA and o -hydroxy-cinnamic acid (oHCA) levels were measured on the 3rd and 7th day of treatment and after 4 days of recovery. Ascorbate peroxidase activity increased in the leaves, but changes in guaiacol peroxidase activity only could be detected in the roots after 7 days. Glutathione reductase activity increased both in the leaves and in the roots after the 3rd day of 100 m m NaCl treatment. Free SA only increased during recovery in the leaves and roots. In the leaves of plants treated with 100 m m NaCl, a slight increase was observed in the free oHCA level, which rose dramatically after recovery, while in the roots an increase could only be seen after recovery. These results suggest that oHCA may serve not only as a precursor of SA but may also have an antioxidant role during salt stress and recovery.  相似文献   

11.
Melatonin (N‐acetyl‐5methoxytryptamine) is an amphiphilic low‐molecular‐weight compound found in evolutionary distant living organisms, from bacteria to mammals. It can be synthesized by plants and acts as a potent antioxidant and/or a regulator of plant growth and development. Here, we investigated the role of melatonin in plant response to drought stress and recovery in maize (Zea mays L.) plants, with an emphasis on its possible photoprotective and antioxidant role and/or signalling function in relation to the stress‐related phytohormones, abscisic acid, salicylic acid and jasmonic acid. Results show a positive correlation between endogenous contents of melatonin and photoprotection, as indicated by the maximum efficiency of photosystem II photochemistry (Fv/Fm ratio), which was confirmed further by exogenous application of melatonin during recovery from drought stress. Melatonin applications during drought recovery improved the Fv/Fm ratio in maize plants exposed to a subsequent drought stress. Furthermore, endogenous contents of melatonin positively correlated with those of stress‐related phytohormones, particularly with those of salicylic acid, although exogenous application of melatonin did not alter the contents of these defence compounds. It is concluded that melatonin can exert a defensive role in maize plants exposed to drought stress, particularly improving the efficiency of photosystem II photochemistry.  相似文献   

12.
水杨酸对渗透胁迫下玉米种子萌发和幼苗生长的影响   总被引：1，自引：0，他引：1  
分别采用不同浓度的甘露醇和水杨酸处理玉米种子。结果表明:水杨酸处理对玉米种子的发芽率以及苗高、根长、根数、苗鲜重、根鲜重及根冠比都得到提高,说明水杨酸对玉米种子发芽和幼苗生长的有促进作用,可以在一定程度上解除渗透胁迫。  相似文献   

13.
The present study assesses the effects of 5‐aminolevulinic acid (ALA, 0, 0.1, 1 and 10 mg l?1) on the growth of oilseed rape (Brassica napus L. cv. ZS758) seedlings under water‐deficit stress induced by polyethylene glycol (PEG 6000, 0 and ?0.3 MPa). Water‐deficit stress imposed negative effects on seedling growth by reducing shoot biomass, cotyledon water potential, chlorophyll content and non‐enzymatic antioxidants (glutathione and ascorbic acid) levels. On the other hand, water‐deficit stress enhanced the malondialdehyde (MDA) content, reactive oxygen species (ROS) production, enzymatic antioxidants activities, reduced/oxidized glutathione ratio (GSH/GSSG) and reduced/oxidized ascorbic acid (ASA/DHA) ratio in seedlings. Application of ALA at lower dosages (0.1 and 1 mg l?1) improved shoot weight and chlorophyll contents, and decreased MDA in rape seedlings, whereas moderately higher dosage of ALA (10 mg l?1) hampered the growth. The study also indicated that 1 mg l?1 ALA improved chlorophyll content, but reduced MDA content and ROS production significantly under water‐deficit stress. Lower dosages of ALA (0.1 and 1 mg l?1) also enhanced GSH/GSSG and ASA/DHA as compared to the seedlings under water‐deficit stress. The antioxidant enzymes (ascorbate peroxidase, peroxidase, catalase, glutathione reductase and superoxide dismutase) enhanced their activities remarkably with 1 mg l?1 ALA treatment under water‐deficit stress. It was also revealed that 1 mg l?1 ALA treatment alone induced the expression of APX, CAT and GR substantially and under water‐deficit stress conditions ALA treatment could induce the expression of POD, CAT and GR to a certain degree. These results indicated that 0.1–1 mg l?1 ALA could enhance the water‐deficit stress tolerance of oilseed seedlings through improving the biomass accumulation, maintaining a relative high ratio of GSH/GSSG and ASA/DHA, enhancing the activities of the specific antioxidant enzymes and inducing the expression of the specific antioxidant enzyme genes.  相似文献   

14.
提高黄瓜幼苗抗冷性研究   总被引：11，自引：0，他引：11  
研究低温，干旱锻炼和外喷ＡＢＡ对黄瓜幼苗的生理影响，初步探讨交叉适应现象的。结果表明，三种处理均提高了黄瓜幼苗的抗冷性和脱落酸含量，体内ＡＢＡ含量与幼苗抗冷力呈极显著正相关，低温锻炼不仅提高了过氧化物酶活，耐用出现了一条新的同工酶带。这条酶带是在处理前细胞内已存在的ｍＲＮＡ上翻译而来，在锻炼过程中喷施５ＦＵ和ＤＤＴＣ均降低了幼苗处理的效果。低温、干旱锻炼不但影响了体内激素的平衡，提高了细胞内渗透调  相似文献   

15.
不同生育期水稻耐冷性的鉴定及耐冷性差异的生理机制   总被引：38，自引：4，他引：38  
以粳稻9516、H45、武育粳、转PEPC基因水稻、Kitaake、苏沪香粳，籼稻扬稻6号、香籼、IR64，培矮64S以及杂交稻粤优938、汕优63、X07S/紫徽100、两优培九等14个水稻品种为材料，分别鉴定了芽期（胚根1 cm, 胚芽0.5 cm）、苗期（三叶）和孕穗期的耐冷性，同时选取南京对水稻播种敏感的自然低温条件，进行低温鉴定。结果表明，芽期存活率、苗期的枯死率和孕穗期结实率均为可靠的水稻耐冷性鉴定指标。进一步从叶片的光合速率、PSⅡ光化学效率（Fv/Fm）、脂肪酸组分、活性氧指标(丙二醛,过氧化氢和超氧阴离子和抗氧化物质(抗坏血酸和谷胱甘肽)的变化等方面，研究耐冷性不同的水稻的耐冷生理机制。表明耐冷的水稻品种武育粳含较多的不饱和脂肪酸，在低温逆境下，膜的流动性愈大，低温对其伤害愈小；对杂交稻汕优63而言，其叶内抵御逆境的保护系统抗坏血酸和谷胱甘肽的循环被较大地激活，特别是谷胱甘肽再生的高速运转，与不耐冷的品种香籼相比，汕优63叶内的过氧化物质累积较少，其耐冷性表现中等。看来水稻叶片维持高的脂肪酸不饱和指数和谷胱甘肽的周转循环能力是水稻耐冷的重要特征。  相似文献   

16.
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17.
Water scarcity is known to be a strong limiting factor affecting maize grown and yield in cold semi-arid regions. Numerous studies have shown that rehydration improves maize growth. Our study aimed to explore the effects of rehydration treatments on maize growth and yield under water and nitrogen stress during different growth stages. We selected the drought-tolerant maize variety Nendan 19 (ND19) and subjected it to water stress during the V6 (sixth-leaf), R2 (filling) and R6 (maturity) growth stages and a rehydration treatment after each stress stage. Our results indicated that N1 (N100 kg N ha−1) and N3 (N300 kg N ha−1) treatments significantly increased the leaf moisture status relative to water content (RWC), bound water content (BWC), free water content (FWC) and water potential (WP)) at different growth stages. Similar trends were observed in the accumulation of plant leaf and root hormones (zeatin+zeatin riboside, indole-3-acetic acid, abscisic acid and gibberellic acid), photosynthetic pigments and chlorophyll fluorescence. However, under the same water stress conditions, they decreased as the N rate increased and reached a minimum value in the S3 (water stress for N3) treatments. In addition, with growth stage advancement and extension of the rehydration time, both showed a gradual upward trend. The results showed that to save water resources in the cold semi-arid region, rehydration treatments (R2S1 and R2S3) significantly increased the photosynthetic pigments and chlorophyll fluorescence parameters, leaf moisture status, biomass, 100-grain weight, hormone content, ear characteristics and grain yield of maize.  相似文献   

18.
外源物质处理对辣椒幼苗抗冷性的影响   总被引：2，自引：1，他引：1  
以辣椒幼苗为试验材料,分别喷施不同浓度亚精胺、壳聚糖、水杨酸、CaCl2、甜菜碱溶液,采用昼温/夜温为10℃/5℃低温胁迫5天后进行相对电导率、冷害指数、可溶性糖含量、脯氨酸含量、丙二醛(MDA)含量等指标的测定和分析,探讨外源物质对低温胁迫下辣椒幼苗的影响及作用效果。结果表明,适宜浓度的外源物质可以显著降低辣椒幼苗低温胁迫后的相对电导率、冷害指数和MDA的积累量,提高可溶性糖、脯氨酸等渗透调节物质的含量,对提高辣椒幼苗抗冷性有积极作用。亚精胺、壳聚糖、水杨酸、CaCl2、甜菜碱提高辣椒幼苗抗冷性的最佳诱导浓度分别为0.5 mmol/L、50 mg/L、2 mmol/L、10 mmol/L、10 mmol/L。  相似文献   

19.
As maize is a chilling-sensitive crop, low temperatures during the early stages of development can be injurious to crop growth and development. Prime mechanism behind chilling-induced damage is oxidative stress. This study was undertaken to improve the chilling tolerance in hybrid maize by seed priming with KCl. For priming, seeds of the maize hybrid Hycorn 8288 were soaked in 50, 100 and 150 mg l−1 aerated solution of KCl for 24 h and then re-dried close to original weight. Primed and untreated seeds were sown at 27 °C (optimal temperature) and at 15 °C (chilling stress) under controlled conditions. Seed priming improved the performance of maize under both normal and stress conditions. It was found that the chilling tolerance in maize is well associated with the enhanced capacity of the anti-oxidative system. Priming with KCl significantly improved the chilling tolerance mainly by the activation of antioxidants including catalase, superoxide dismutase and ascorbate peroxidase enzymes. KCl treatments also improved the germination rate and time, root and shoot length, and fresh and dry weights of seedlings compared with control. Soluble sugars and α-amylase activity determined as general metabolic indicators of stress were also improved by seed priming with KCl. Other possible bases of chilling tolerance in maize included maintenance of high tissue water contents, reduced electrolyte leakage and carbohydrate metabolism. Seed treatment with 100 mg l−1 KCl was the best treatment to improve the performance of hybrid maize both under normal and chilling stress conditions.  相似文献   

20.
The time course of injuries and electrolyte leakage as well as changes in leaf water content and relative turgidity during chilling at 5°C, 65 or 100 % relative humidity (RH) were determined for seedlings of two maize hybrids differing in chilling tolerance.
In the course of chilling of entire seedlings the statistically significant injuries and increased leakage of electrolytes occurred first, followed by significant water deficit in leaves which was independent of RH and genotype. However, during prolonged chilling high and significant correlation between the level of chilling-induced water stress and the extent of injuries was observed. Thus it has been assumed that the main factor responsible for primary chilling injuries in maize seedlings is the immediate influence of chilling temperatures on the cell membranes, and not the secondary water stress. The level of the water stress and the extent of the dehydration injuries under chilling conditions depended on the chilling sensitivity of the genotype. Differences between the examined genotypes consisted not only in delayed chilling injuries in a chilling tolerant hybrid, but also in significantly lesser effects of these injures on water relations.
However, exposure to low temperature of the aboveground part or of the roots of the seedlings only, caused first the chilling-induced marked water deficit in the leaves and next increased leakage of electrolytes. A direct effect of chilling temperature on the membranes in a situation when only a part of the seedling is being chilled, may be less harmful to the plant as a whole owing to normal functioning of the non-chilled part.  相似文献   

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