Spd浸种对盐胁迫下番茄（Solanum lycopersicum)幼苗的保护效应

通过水培试验,研究了100 mmol/L NaCl盐浓度下,0.25 mmol/L Spd浸种处理对两个番茄品种白果强丰(耐盐基因型)和江蔬14号(盐敏感基因型)植株干重、根冠比(R/T)、幼苗叶片和根系抗氧化酶活性及活性氧含量的影响.具体试验处理如下:(a) 对照(蒸馏水浸种+ 0 mmol/L NaCl),(b) NaCl (蒸馏水浸种+ 100 mmol/L NaCl),(c) Spd(0.25 mmol/L Spd浸种 +100 mmol/L NaCl).结果表明,在盐胁迫下,两个番茄品种幼苗叶片和根系内超氧化物歧化酶(SOD)、过氧化物酶(POD)、过氧化氢酶(CAT)活性升高,H2O2含量和O·-2产生速率增高,幼苗生长受到抑制,幼苗地上部、地下部干重均明显低于对照,R/T增大,且江蔬14号的变化幅度大于白果强丰.Spd浸种处理降低了盐胁迫下番茄幼苗叶片和根系内O·-2产生速率和H2O2含量,进一步提高了SOD、POD和CAT活性,促进幼苗干重增加,缓解了盐胁迫对植株的伤害.与耐盐基因型番茄品种白果强丰相比,Spd浸种处理对盐敏感基因型番茄品种江蔬14号的作用效果更为明显.总之,Spd浸种处理通过提高盐胁迫下植株体内抗氧化酶活性,降低ROS水平来缓解盐胁迫对番茄幼苗的伤害,提高幼苗耐盐能力.     

Effect of pretreating the seeds with extracts of Phormidium foveolarum on growth and development of maize seedlings

Summary The effect of pretreatment of seeds of Maize type Ganga 3 and 41 with extract of P. foveolarum has been studied. The observations show an alround beneficial effect on the growth and development of the seedlings.     

外源水杨酸对氯化钠胁迫下番茄幼苗糖代谢的影响

采用营养液水培法,用100、300和500 mg·L^-1不同浓度的水杨酸（SA）处理‘辽园多丽’番茄幼苗,测定在NaCl胁迫下番茄幼苗叶片果糖、葡萄糖、蔗糖含量和蔗谢代谢相关酶活性（酸性转化酶AI、中性转化酶NI、蔗糖磷酸合成酶SPS、蔗糖合成酶活性SS）的变化.结果表明：SA处理叶片可以维持或提高NaCl胁迫条件下番茄幼苗叶片果糖、葡萄糖含量及AI、NI、SPS和SS活性,其最高值分别比单纯NaCl处理植株增加30.0%、31.1%、24.7%、27.9%、22.0%和24.5%;但对NaCl胁迫条件下番茄幼苗叶片蔗糖含量的影响不大.表明水杨酸可以通过提高NaCl胁迫下番茄叶片转化酶活性来提高番茄叶片果糖和葡萄糖含量,从而缓解NaCl胁迫对番茄的伤害,其中以500 mg·L^-1的SA处理效果较理想.     

水杨酸对NaCl胁迫下菊芋幼苗光合作用及离子吸收的影响

为探明水杨酸(SA)对NaCl胁迫下菊芋耐盐生理的调控作用,研究了100μmol·L-1水杨酸对不同浓度NaCl胁迫下菊芋幼苗光合响应特征及离子吸收运输的影响.结果表明:施用水杨酸不仅能够有效缓解NaCl胁迫对菊芋光合作用的抑制,促进NaCl胁迫下菊芋幼苗各种光合色素含量、净光合速率、蒸腾速率、气孔导度和水分利用效率的增加,降低细胞间隙CO2浓度,同时也能明显降低NaCl胁迫下菊芋体内Na+的积累,促进菊芋幼苗对K+和Ca2+的吸收和向上运输,其中在100 mmol·L-1 NaCl处理下施用水杨酸处理的菊芋叶片中K+和Ca2+含量分别比未施用水杨酸处理增加了12.9％和14.7％,而Na+含量则降低了30.6％.由此证明,一定浓度外源水杨酸的施用有利于促进NaCl胁迫下菊芋幼苗光合功能的改善,以及有效维持菊芋幼苗体内矿质营养元素含量平衡,从而增强菊芋对NaCl胁迫的抗性,提高NaCl胁迫下的生产力.     

Evidence for a role of salicylic acid in the oxidative damage generated by NaCl and osmotic stress in Arabidopsis seedlings.

Previous studies have shown that salicylic acid (SA) is an essential component of the plant resistance to pathogens. We now show that SA plays a role in the plant response to adverse environmental conditions, such as salt and osmotic stresses. We have studied the responses of wild-type Arabidopsis and an SA-deficient transgenic line expressing a salicylate hydroxylase (NahG) gene to different abiotic stress conditions. Wild-type plants germinated under moderate light conditions in media supplemented with 100 mM NaCl or 270 mM mannitol showed extensive necrosis in the shoot. In contrast, NahG plants germinated under the same conditions remained green and developed true leaves. The lack of necrosis observed in NahG seedlings under the same conditions suggests that SA potentiates the generation of reactive oxygen species in photosynthetic tissues during salt and osmotic stresses. This hypothesis is supported by the following observations. First, the herbicide methyl viologen, a generator of superoxide radical during photosynthesis, produced a necrotic phenotype only in wild-type plants. Second, the presence of reactive oxygen-scavenging compounds in the germination media reversed the wild-type necrotic phenotype seen under salt and osmotic stress. Third, a greater increase in the oxidized state of the glutathione pool under NaCl stress was observed in wild-type seedlings compared with NahG seedlings. Fourth, greater oxidative damage occurred in wild-type seedlings compared with NahG seedlings under NaCl stress as measured by lipid peroxidation. Our data support a model for SA potentiating the stress response of the germinating Arabidopsis seedling.     

Effect of salicylic acid on nitrate reductase activity in maize seedlings

The effect of different concentrations of salicylic acid on total Kjeldahl nitrogen and nitrate reductase activity in the maize ( Zea mays L.) seedling was studied. The total nitrogen of the maize embryonic axis (root + shoot) from seedlings raised with 10 m M Ca(NO₃)₂ for 5 days was substantially higher than that from the control when 0.01 m M salicylic acid was supplied. As supply of high (1 m M ) concentrations of salicylic acid decreased the accumulation of organic nitrogen. The in vivo activity of nitrate reductase in the roots increased at low concentrations of salicylic acid, while high concentrations were inhibitory. The stimulative concentration of the acid protected in vivo loss of nitrate reductase activity under non-inducing conditions, whereas it had no effect on in vitro loss of enzyme. It is suggested that salicylic acid increases in vivo enzyme activity indirectly, to some extent by protecting the natural inactivation of the enzyme.     

Treatment with acetyl salicylic acid protects muskmelon seedlings against drought stress

Salicylic acid (SA) is a common plant-produced signal molecule that is responsible for inducing tolerance to a number of biotic and abiotic stresses. An experiment was, therefore, conducted to test whether acetyl salicylic acid (ASA) application at various concentrations through seed soaking or foliar spray would protect muskmelon [Cucumis melo L. (reticulatus group)] seedlings, subjected to drought stress. Twenty-three-day-old plants pre-treated with ASA (0, 0.1, 0.25, 0.50 or 1.0 mM) were subjected to drought stress for 1 week in a greenhouse. ASA applied either through seed soaking or through foliar spray was effective within the range of 0.1–1 mM in providing drought stress protection in muskmelon seedlings; however, there was no difference between application methods indicating that both methods provided similar levels of protection. ASA significantly affected all seedling growth and stress indicator variables measured except leaf number and root dry weight. The best protection appeared to be obtained from seedlings pre-treated with lower concentrations of ASA. Even though both methods provided similar means of protection, due to its simplicity and practicality, soaking muskmelon seeds prior to sowing in up to 0.5 mM ASA would be a more desirable method.     

Alleviation of the adverse effects of NaCl on germination of maize grains by calcium

The lengths of roots and shoots, fresh and dry matter yield, and the contents of insoluble saccharides and free amino acids were reduced with the rise in NaCl concentration. However, under combination of NaCl with Ca²⁺ ions, these parameters generally raised. Contents of soluble saccharides, proline and quaternary ammonium compounds increased with increasing NaCl concentration, but under addition of CaCl₂ or CaSO₄, contents of these compounds were decreased. Low concentrations of NaCl stimulated soluble proteins, production, but higher concentrations decreased the content of soluble proteins. Addition of Ca²⁺ in the media did not improve the soluble protein production. Insoluble proteins content was increased with the rise of salinity level, but these effects were more pronounced with NaCl and CaCl₂ or CaSO₄ than with NaCl only.     

Exogenously applied ascorbic acid ameliorates detrimental effects of NaCl and mannitol stress in Vicia faba seedlings

The adverse effects of either NaCl or mannitol on growth, nitrogen content, and antioxidant system in Vicia faba seedlings were investigated. The role of exogenous ascorbic acid in increasing resistance to these stressors was also evaluated. Thus, with an increase in concentration of either NaCl or mannitol in culture media, a progressively greater significant decrease in percentage germination, in growth parameters, and in nitrogen constituents of the germinating beans, was observed. On the other hand, amide-, nitrate-, and total soluble-N contents appeared to show a progressive significant increase. Exogenous addition of ascorbic acid (4 mM) to the stressful media induced a pronounced significantly increased percentage germination and the growth attributes, whereas nitrogen constituents were variably changed in relation to values maintained in beans treated with either NaCl or mannitol. Furthermore, exogenous addition of ascorbic acid to NaCl or mannitol media induced a significant increase in the contents of ascorbate and glutathione and enzymatic antioxidant activities, in particular, in beans treated with the three highest concentrations of NaCl or mannitol, throughout the period of the experiments (12 days). Thus, ascorbic acid ameliorates the adverse effects of the stressful media; the magnitude of amelioration being a function of the type and the concentration of the stressful agent as well as of the duration of treatment. The importance of the above-mentioned changes in growth and metabolism to stress tolerance in broad bean is discussed.     

Amelioration of salt-induced oxidative stress in eggplant by application of 24-epibrassinolide

The effects of exogenous 24-epibrassinolide (EBR) on the growth, oxidative damage, antioxidant system and ion contents in eggplant (Solanum melongena L.) seedlings under salt stress were investigated. Eggplant seedlings were exposed to 90 mM NaCl with 0, 0.025, 0.05, 0.10 and 0.20 mg dm⁻³ EBR for 10 d. EBR, especially at concentration 0.05 mg dm⁻³, alleviated growth suppression caused by NaCl stress, decreased electrolyte leakage, superoxide production and content of malondialdehyde and H₂O₂ in NaCl-treated plants. EBR also increased activities of superoxide dismutase, guaiacol peroxidase, catalase and ascorbate peroxidase and the contents of ascorbic acid and reduced glutathione. Furthermore, we also found that Na⁺, Cl⁻ contents were decreased, K⁺, Ca²⁺ contents and K⁺/Na⁺, Ca²⁺/Na⁺ ratios were increased in the presence of EBR under salt stress.     

外源SA和NO对NaCl胁迫下番茄幼苗生长、光合及离子分布的影响

以番茄(Lycopersicon esculentum Mill.)品种‘秦丰保冠’为试材,采用营养液培养法,研究单独和复配施用外源水杨酸(SA)、一氧化氮(NO)供体硝普钠(SNP)对100mmol/L NaCl胁迫下番茄幼苗生长、光合及离子分布的影响。结果表明:(1)单独和复配外施SA、SNP均能有效抑制NaCl胁迫下番茄幼苗叶片光合色素(Chla、Chlb、Chla+b和Car)含量、Chla/b值、净光合速率(Pn)、蒸腾速率(Tr)、气孔导度(Gs)、瞬时水分利用效率(WUEt)、表观光能利用效率(LUEapp)和表观CO2利用效率(CUEapp)的下降及Car/Chla+b值和胞间CO2浓度(Ci)的升高,并以SA和SNP复配处理效果最明显。(2)NaCl胁迫下,外源SA、SNP单独和复配处理的番茄幼苗各器官(叶、茎和根)中Cl-、Na+含量和Na+/K+、Na+/Ca2+、Na+/Mg2+值显著降低,而K+、Ca2+和Mg2+的含量却不同程度提高,其中以SA和SNP复配处理效果最好。(3)单独和复配外施SA、SNP均能有效减轻NaCl胁迫对番茄幼苗生长的抑制作用,并促进各器官生物量的积累和壮苗的形成,且以SA和SNP复配处理效果更佳。研究表明,复配外施SA和SNP在诱导番茄幼苗提高抗(耐)盐能力方面具有协同增效作用。     

外源NO和SA对盐胁迫下番茄幼苗叶片膜脂过氧化及AsA-GSH循环的影响

以番茄(Lycopersicon esculentum Mill.)品种‘秦丰保冠’为试材,在水培条件下研究单独和复配施用一氧化氮(NO)供体硝普钠(SNP)、水杨酸(SA)对100 mmol/L NaCl胁迫下番茄幼苗的生长、叶片光合作用、膜脂过氧化及抗坏血酸-谷胱甘肽(AsA-GSH)循环的影响。结果显示,盐胁迫能显著影响番茄幼苗的生长、光合作用和活性氧代谢系统的相关指标。单独或复配施用SNP、SA均能有效缓解番茄幼苗的盐渍伤害,并以SNP和SA复配处理效果最好。处理3~7 d时,叶片PSⅡ最大光化学效率(Fv/Fm)、净光合速率(Pn)、APX、GR、DHAR的活性、AsA和GSH含量分别较胁迫处理有不同程度的提高;而H2O2、MDA、DHA、GSSG的含量和电解质渗漏率分别较胁迫处理有不同程度的降低。研究结果表明盐胁迫下外源NO、SA单独或复配处理均能通过维持或协调作用促进番茄相关抗氧化酶活性的提高和抑制抗氧化剂含量的降低,起到维持AsA-GSH循环高效运转、减轻膜脂过氧化、促进光合作用、改善植株生长发育和提高幼苗盐渍抗性的作用,且NO和SA复配处理时具有协同增效的作用。     

低氧胁迫下24-表油菜素内酯对黄瓜幼苗叶片光合特性及多胺含量的影响

采用1/2 Hoagland营养液培养,研究了低氧胁迫下24-表油菜素内酯(EBR)对黄瓜幼苗叶片光合特性及多胺含量的影响.结果表明：低氧胁迫下黄瓜幼苗的净光合速率(P_n)、气孔导度(g_s)、蒸腾速率(T_r)、胞间CO₂浓度(C_i)显著下降,而叶绿素含量显著提高,幼苗生长受抑;低氧胁迫显著提高了黄瓜幼苗叶片的腐胺(Put)、亚精胺(Spd)、精胺(Spm)、多胺(PAs)含量和Put/PAs,但降低了(Spd+Spm) /Put.低氧胁迫下,外源EBR不仅显著提高了黄瓜幼苗的P_n、g_s、T_r及叶绿素含量,也显著提高了黄瓜幼苗叶片的游离态Spm、结合态Spd、Spm及束缚态Put、Spd、Spm含量,促进了PAs的进一步积累,且降低了Put/PAs,提高了(Spd+Spm)/Put．可见,外源EBR调节了黄瓜幼苗内源多胺含量及形态的变化,维持了较高的光合性能,促进了叶面积和干物质量的显著增加,缓解了低氧胁迫对黄瓜幼苗的伤害.     

Amelioration of NaCl stress by triadimefon in peanut seedlings

Peanut (Arachis hypogaea L.cv. VRI-2) seeds were imbibed in distilled water(control), 30 mM NaCl (stressed) and 30 mM NaCl + 10 mg L^-1 triadimefon for 12 h and grown in a seed germinator with a day/night temperature of 30/22 °C and a photoperiod of 16 h with a PPFD of 250 µEm^-2 s_-1. Seedlings were irrigated with respective treatment solutions. Fifteen days old seedlings were harvested and used for the study. The NaCl stress decreased seedling growth, dry weight, photosynthetic pigments, protein content and the level of proline oxidase activity and it increased proline, glycine betaine content, protease and ATPase activities. Triadimefon treatment ameliorated the stress caused NaCl by increasing root growth, dry weight, chlorophyll, carotenoid, protein and glycine betaine contents and by decreasing proline accumulation, proline oxidase levels and ATPase. The stress amelioration conferred by triadimefon may be mediated by increased protein synthesis, osmoregulation and reduced energy requirement.     

低氧胁迫下24-表油菜素内酯对黄瓜幼苗根系生长及其无氧呼吸同工酶表达的影响

采用营养液水培,研究了低氧胁迫下24-表油菜素内酯(EBR)对黄瓜幼苗根系生长及其无氧呼吸同工酶表达的影响.结果表明:低氧胁迫增强了黄瓜幼苗根系丙酮酸脱羧酶(PDC)、乙醇脱氢酶(ADH)、乳酸脱氢酶(LDH)同工酶的表达,低氧胁迫下施用外源EBR的第3天PDC、ADH同工酶的表达量分别提高了18.8％、28.8％,而第6、第9天PDC、ADH、LDH同工酶的表达减弱,比单纯低氧处理分别降低19.5％、25.6％、53.4％及26.4％、26.0％、28.4％;低氧胁迫至第9天,黄瓜幼苗根系的生长受到了显著抑制(P＜0.05),而低氧胁迫下施用EBR,黄瓜幼苗根系的生长受抑制程度减轻,其根系总长、干重、根尖数较单纯低氧处理显著增加(P＜0.05),低氧抑制了黄瓜幼苗根系的生长,低氧胁迫下营养液添加EBR可调节黄瓜根系无氧呼吸同工酶的表达,缓解低氧胁迫对黄瓜幼苗根系的伤害.     

油菜素内酯对氯化钠胁迫下黄瓜幼苗的缓解效应

研究了2,4-表油菜素内酯(EBR)对氯化钠胁迫下黄瓜幼苗叶片光合作用及抗氧化系统的影响．结果表明： 与对照相比,氯化钠胁迫导致黄瓜幼苗叶片超氧阴离子产生速率、过氧化氢和丙二醛含量、细胞膜透性显著升高,净光合速率、气孔导度、蒸腾速率、胞间CO₂浓度显著下降,幼苗生长显著受抑．EBR可提高黄瓜幼苗叶片超氧化物歧化酶、过氧化物酶、过氧化氢酶等抗氧化酶活性,降低超氧阴离子产生速率、过氧化氢和丙二醛含量及细胞膜透性,维持良好的光合性能,从而促进幼苗生长,有效缓解氯化钠胁迫造成的伤害.
     

The alternative pathway in cucumber seedlings under low temperature stress was enhanced by salicylic acid

The alternative pathway is a cyanide-resistant and non-phosphorylatory electron transport pathway in mitochondria of higher plants. Alternative oxidase (AOX) is the terminal oxidase of this pathway. Our present study investigated the effect of exogenous salicylic acid (SA) on alternative pathway in cucumber (Cucumis sativus L.) seedlings under low temperature stress. Results showed that during the process of low temperature stress, the alternative pathway capacity was enhanced as AOX expression increased in SA pretreated seedlings. Compared with seedlings without SA pretreatment, slower decrease of relative water content and lower levels of electrolyte leakage, H₂O₂ and malonyldialdehyde content were detected in SA pretreated seedlings. These results indicated that SA could alleviate the injury caused by low temperature on cucumber seedlings. Since the special protective functions of alternative pathway and AOX in plants, we suggested that the alternative pathway was related to SA-mediated plant resistance to environmental stresses such as low temperature.     

Physiological effects and transport of 24-epibrassinolide in heat-stressed barley

This paper presents a study of the metabolic response (dark respiration intensity, photosystem II efficiency, metabolic activity) and the yield of barley treated with 24-epibrassinolide and subjected to high-temperature stress. Transport of exogenously applied 24-epibrassinolide in barley and changes in the profile of brassinosteroids that may occur in tissues after 24-epibrassinolide application were also studied. The water solution of 24-epibrassinolide (0.005 and 0.25 mg dm⁻³) was applied via infiltration of the first and second leaves of 12-day-old seedlings. Control plants were treated with water solution of hormone solvent (ethanol). Fifteen-day-old plants were subjected to high-temperature stress (42°C for 3 h). The influence of hormone treatment and stress conditions was investigated in the first and second leaves based on measurements of PSII efficiency. The aftereffect of plant treatment was investigated in the seventh leaf (measurements of PS II efficiency, dark respiration intensity, metabolic activity). The transport efficiency of 24-epibrassinolide exogenously applied to the first and second leaves, as well as the profile of other brassinosteroids, was also measured on the seventh leaf. Finally, yield formation was estimated. 24-epibrassinolide showed protective action, which manifested itself in the improved functioning of PSII, but this was observed in case of higher hormone concentration and only for the first, older leaf. The PSII efficiency of the seventh leaf was similar in plants treated with brassinosteroid and in the control plants, whereas the respiration intensity and metabolic activity decreased in plants previously treated with higher concentration of 24-epibrassinolide. The use of a higher hormone concentration at the seedling phase ultimately resulted also in lower crop yield. Brassinosteroids—brassinolide and castasterone—were detected in barley leaves. 24-epibrassinolide was found only in trace amounts in control plants. Its exogenous application directly to the apoplast of the first and second leaves resulted in an increase in the 24-epibrassinolide content in the seventh leaf, but did not depend on whether a high or low concentration had been applied to the plants.