Salicylic acid induced physiological and biochemical changes in wheat seedlings under water stress

Salicylic acid (SA) is an important signal molecule modulating plantresponses to stress. It is recently reported to induce multiple stresstolerancein plants including drought. An experiment was, therefore, conducted toascertain the effect of salicylic acid on the growth and metabolic profile ofwheat seedlings under water stress. Irrespective of the SA concentration(1–3 mM) and water stress, SA treated plants showed, ingeneral, a higher moisture content, dry mass, carboxylase activity of Rubisco,superoxide dismutase (SOD) activity and total chlorophyll compared to those ofuntreated seedlings. SA treatment, under water stress, protected nitratereductase (NR) activity and maintained, especially at 3 mM SAconcentration, the protein and nitrogen content of leaves compared to watersufficient seedlings. Results signify the role of SA in regulating the droughtresponse of plants and suggest that SA could be used as a potential growthregulator, for improving plant growth under water stress.     

外源水杨酸对干旱胁迫下小冠花种子萌发及幼芽生理特性的影响

以豆科牧草“绿宝石”小冠花为试材,研究PEG-6000(浓度8%和12%)模拟干旱胁迫下不同浓度外源水杨酸(0、0.5、1.0和2.0 mmol·L^-1)对小冠花种子萌发和幼芽生理特性的影响.结果表明: 0.5～1.0 mmol·L^-1水杨酸显著提高了干旱胁迫下小冠花种子发芽率、发芽势、发芽指数、活力指数和芽长,12%PEG胁迫下1.0 mmol·L^-1水杨酸处理小冠花幼芽干质量显著高于干旱处理.0.5～1.0 mmol·L^-1水杨酸处理显著提高了干旱胁迫下小冠花幼芽脯氨酸、可溶性蛋白含量,显著提高了过氧化氢酶、过氧化物酶、超氧化物歧化酶活性,显著降低了幼芽细胞电解质渗透率、H₂O₂含量、O₂^-·产生速率,其中以1.0 mmol·L^-1水杨酸处理效果最好.水杨酸浓度超过2.0 mmol·L^-1时对干旱胁迫没有缓解效应.表明适宜浓度的水杨酸(0.5～1.0 mmol·L^-1)可以提高小冠花幼芽渗透调节能力和抗氧化能力,促进小冠花生长,缓解干旱胁迫伤害.     

Salicylic acid induces physiological and biochemical changes in three Red bayberry (Myric rubra) genotypes under water stress

Water stress is one of the main environmental stresses that affect plant growth and development. Salicylic acid (SA) induces water stress tolerance in plants. In this study, the effect of exogenous SA on physiological and biochemical process in Red bayberry (Myric rubra) seedlings, of three different genotypes, that were grown under water stress (soil ranging from 20 to 50 % of field capacity) was evaluated. Results showed that water stress severely affected the relative water content (RWC), photosynthesis, stomatal conductance and enzymes activities. Genotypes differed in RWC, Chlorophyll content, gas exchange parameter, antioxidant enzymes activities and proline, and the genotype Biqi had the RWC, photosynthesis, stomatal conductance and enzymes activities greater than the other two genotypes Wangdao and Shenhong. SA treated plants showed, in general, a higher RWC, chlorophyll content, photosynthetic rate, stomatal conductance, superoxide dismutase activity and proline content, and a lower relative electrolyte conductivity, methane dicarboxylic aldehyde content and catalase activity compared to those of untreated seedlings. These results signified the role of SA in diminishing the negative effects of drought on Red bayberry plants and suggest that SA could be used as a potential growth regulator, for improving plant growth under water stress.     

Salicylic acid alleviates adverse effects of heat stress on photosynthesis through changes in proline production and ethylene formation

We investigated the potential of salicylic acid (SA) in alleviating the adverse effects of heat stress on photosynthesis in wheat (Triticum aestivum L.) cv WH 711. Activity of ribulose 1,5-bisphosphate carboxylase (Rubisco), photosynthetic-nitrogen use efficiency (NUE), and net photosynthesis decreased in plants subjected to heat stress (40°C for 6 h), but proline metabolism increased. SA treatment (0.5 mM) alleviated heat stress by increasing proline production through the increase in γ-glutamyl kinase (GK) and decrease in proline oxidase (PROX) activity, resulting in promotion of osmotic potential and water potential necessary for maintaining photosynthetic activity. Together with this, SA treatment restricted the ethylene formation in heat-stressed plants to optimal range by inhibiting activity of 1-aminocyclopropane carboxylic acid (ACC) synthase (ACS). This resulted in improved proline metabolism, N assimilation and photosynthesis. The results suggest that SA interacts with proline metabolism and ethylene formation to alleviate the adverse effects of heat stress on photosynthesis in wheat.     

水杨酸在植物抗环境胁迫中的作用

水杨酸在植物的抗病方面发挥着重要作用。近年来的研究还表明 ,水杨酸在植物的抗冷、热、盐、干旱、臭氧、重金属等环境胁迫方面也有明显的作用。该文介绍近年来有关水杨酸在植物抗环境胁迫方面的研究进展 ,并探讨了其作用机理。     

Salicylic acid induces physiological and biochemical changes in Torreya grandis cv. Merrillii seedlings under drought stress

Key message

SA treatment effectively ameliorated the negative effect of moderate drought stress on T. grandis Seedlings through increasing the water content, Pn, proline content, antioxidant enzymes activity and reducing MDA.

Abstract

Water availability is one of the most critical factors that limits the growth and development of plants. Salicylic acid (SA) is an important signal molecule that modulates plant responses to abiotic stress. To elucidate the regulating mechanism of exogenous SA on Torreya grandis cv. Merrillii under different water stresses, a pot experiment was conducted in a greenhouse. Exposure of T. grandis seedlings to drought conditions resulted in reduced growth rate that was associated with a decline in water content and CO₂ assimilation. Foliar application of SA effectively increased the water content, net CO₂ assimilation rate, proline content and antioxidant enzymes activity in the plants, which helped T. grandis to acclimate to moderate drought stress and increase the shoot dry matter. However, when the plants were under severe drought stress, the relative water content and CO₂ assimilation in the SA-treated plants were significantly lower than those in the control plants. Therefore, our results indicated that SA can effectively ameliorate the negative effect of moderate drought stress on T. grandis seedling growth.     

水杨酸和热锻炼诱导的高羊茅幼苗的耐热性与抗氧化的关系

研究了水杨酸（SA）处理和热锻炼（HH）对高羊茅（Festuca arundinacea Schred.)幼苗耐热性的影响和在耐热性诱导过程中植物体内可溶性蛋白含量与超氧化物歧化酶（SOD）,过氧化的酶（POD）和过氧化氢酶（CAT）等3种抗氧化酶的活性变化。结果表明：0.5mmol/L男SA预处理能显著提高高羊茅幼苗在42℃热胁迫（HS）后转至常温下恢复生长18d时的苗高,绿叶数和绿叶指数;在常温下SA提高高羊茅幼苗的CAT活性,降低POD活性,而对SOD的影响不显著;SA和HH均能降低高羊茅幼苗在HS下细胞外渗液电导率,提高可溶性蛋白的含量和SOD、CAT活性,但不能显著提高POD活性。因此,推测SA与HH提高耐热性上具有相似的机理。     

盐胁迫下水杨酸及其衍生物对小黑麦幼苗生理特性的影响

盐胁迫下,适当浓度的两种酚酸均能降低幼苗叶片电导率和丙二醛(MDA)含量,增加根系活力。在相同处理浓度下．5-磺基水杨酸提高幼苗生理特性的效果比水杨酸好。     

Phospholipid changes in wheat and barley leaves under water stress

Total phospholipid content of leaves of wheat and barley increased and phospholipid components changed under water stress. Notable among these were the absence of phosphatidyl serine in barley varieties, decrease in phosphatidyl glycerol content in a less drought-tolerant variety of wheat (S-308) and barley (BG-25), and appearance of phosphatidic acid in both crops. The phospholipid content and its components did not return to normal upon release of the stress by subsequent irrigations. Such observations are indicative of water stress effected alterations in membranes.     

Leaf morphology and water status changes in Triticum durum under water stress

Water relations, leaf morphology and the chemical composition of cell walls in irrigated and unirrigated plants of three durum wheat eultivars were measured at two growth stages (booting and flowering). Plant response to water stress differed at the two stages: cell wall elasticity increased at booting and osmotic potential values decreased at flowering; this may be due to the changes in stress history, leaf development and plant growth stage between the two harvests. Leaf tissue characteristics were modified by water stress only at flowering: accumulation of fibrous constituents and hemicellulose in the cell walls, reduction of acid detergent fiber (ADF) per unit of leaf area, increase in specific leaf weight (SLW), decrease in turgid weight/dry weight ratio (TW/DW) and alteration in mesophyll cell morphology (cell area / ceil perimeter ratio) were observed.
Generally, cv. Valforte (the less drought-resistant cultivar) had the greatest mesophyll cell area and perimeter and it had greater values of neutral detergent fiber (NDF) at the booting stage than cv. Appulo. Reactivity to water stress differed in the eultivars: Valforte showed the greatest increase in hemicellulose content and decrease in cell dimensions under drought at flowering.
No significant relationships between osmotic potential and mesophyll cell characters were observed; there were no correlations among cell wall elasticity, cell morphology and the chemical components of leaf tissue. The total fiber content and the hemicellulose per unit of leaf area were correlated with the TW/DW ratio at flowering. This parameter decreased more in plants subjected to water stress owing to accumulation of hemicellulose. Correlations between leaf structural constituents and $$ suggest that the absorptive capacity of the cell wall may significally affect the osmotic volume of the cell.     

Morphological and biochemical changes in two parsley varieties upon water stress

The study was carried out to determine the responses of two parsley (Petroselinum crispum L.) hybrids; plain and curly- leafed to water stress. Besides the control, three irrigation treatments (10, 30 and 50 % of control water amount) were applied. Plant yield (leaf area, stem length and diameter, number of leaves) and quality (fresh and dry weights and concentrations of chlorophyll, carotenes, anthocyanins and vitamin C) were measured. The responses of plant yield and quality varied according to the hybrid and water treatment. The high quality was observed in curly- leafed parsley if compared to plain- leafed parsley, which had higher yield (stem length and diameter, leaf area). Moreover, water stress improved quality but decreased yield parameters in both hybrids.     

Salicylic acid and nitric oxide alleviate osmotic stress in wheat (Triticum aestivum L.) seedlings

Salicylic acid (SA) and nitric oxide (NO) are reported to alleviate the damaging effects of stress in plants rather similarly when applied at appropriate low concentrations. An experiment was therefore conducted to study the impact of SA, sodium nitroprusside (SNP; as NO donor), and methylene blue (MB; as a guanylate cyclase inhibitor) on wheat seedling performance under osmotic stress. Osmotic stress significantly reduced shoot fresh weight (SFW), chlorophyll contents (Chla, Chlb, total Chl), and membrane stability index (MSI) and also increased malondialdehyde (MDA) level, lipoxygenase (LOX) activity, and hydrogen peroxide production. Moreover, enzymatic antioxidant activities including superoxide dismutase, guaiacol peroxidase, and glutathione reductase activity were enhanced under osmotic stress. On the contrary, SA or SNP pretreatment reduced the damaging effects of osmotic stress by further enhancing the antioxidant activities that led to increased SFW, Chl, and MSI and reduced MDA level and LOX activity. However, pretreatment of plants with MB reversed or reduced the protective effects of SA and SNP suggesting that the protective effects were likely attributed to NO signaling. Therefore, NO may act as downstream of SA signaling in reduction of induced oxidative damage in wheat seedlings.     

水胁迫下多角度幼龄檀香图像颜色变化分析及含水率反演

干旱与水淹胁迫是植物遭受的主要非生物胁迫,对植物的生理活动造成严重影响.本研究基于单反相机获取幼龄檀香的纵向和冠层叶片图像,使用分割算法提取叶片和颜色特征,然后讨论两种胁迫条件下多角度檀香叶片颜色变化及含水率反演.结果表明:干旱组在胁迫前期(前6d)叶片亮度降低,绿色分量增加,之后叶片亮度增加,绿色分量降低;水淹组叶片在整个胁迫周期亮度持续降低,黄色分量增加;对照组则与干旱组的变化趋势类似,但拐点出现的时间较晚.当叶片含水率在50%~70%时,随着含水率的增加,彩色图像的红(R)、绿(G)、蓝(B)通道值均会减小;但当叶片含水率小于40%时,会出现R通道值大于G通道值的现象.在使用极限学习机反演含水率时,校正后的颜色分量对拟合优度及预测精度均有所提高.纵向图像更适合用来反演叶片的含水量,决定系数和平均绝对百分比误差分别为0.8352和2.3%;而冠层图像对叶片等效水厚度的表达更准确,上述指标分别为0.7924和9.3%.     

水杨酸对枣树组织培养苗几种生理生化指标的影响

研究了不同浓度水杨酸(0mmol／L、1mmol／L、5mmol／L、10mmol／L)对枣树一年生组织培养苗叶片含水量、可溶性糖含量、可溶性蛋白含量及过氧化物酶活性的影响。结果表明,枣树组织培养苗叶面喷洒不同浓度水杨酸可提高其叶片含水量、可溶性糖含量、可溶性蛋白含量和过氧化物酶活性,其中以1mmol／L喷洒效果显著。     

Growth of tomato (Lycopersicon esculentum) in response to salicylic acid under water stress

Abstract

Plants of Lycopersicon esculentum L. cv. K-25 were subjected to water stress by withholding water for 10 days at 20 (WS I) and 30 (WS II) days after sowing (DAS). Seedlings were sprayed with double distilled water (DDW) or 10^?5M salicylic acid (SA) at 45 DAS. The water stress at earlier stage of growth (20 day stage) was more inhibitory as compared to the later stage (30 day stage). The plants exposed to water stress exhibited a significant (p<0.05) decline in photosynthetic parameters, membrane stability index (MSI), leaf water potential, activity of nitrate reductase (NR), carbonic anhydrase (CA), chlorophyll and relative water content (RWC). A follow-up treatment with SA protected against the stress generated by water and significantly improved the above parameters. However, proline content and antioxidant enzymes increased under drought as well as under SA treatments.     

水分胁迫下苹果幼苗超弱发光及一些生理特性的变化

以苹果属八棱海棠和平邑田茶当年实生幼苗为试材,研究了在用15％ PEG 6000溶液模拟干旱处理条件下幼苗的超弱发光(ultraweak luminescence,UWL)及ATP含量、呼吸与活性氧(O2^-)产生速率等一些生理特性的变化。结果表明,随水分胁迫时间的延长,幼苗的UWL、ATP含量、蛋白质含量均呈下降趋势,呼吸速率先升后降,而丙二醛(MDA)含量与O2^-的产生速率呈明显上升趋势。品种间各指标比较表明,八棱海棠比平邑田茶具有较强的抗水分胁迫能力,UWL反映幼苗品种抗旱性结果与用其它生理指标测定的结果一致。分析认为,幼苗UWL强度没有随胁迫下氧自由基的增加而增加,说明活性氧不是导致UWL的唯一原因。苹果幼苗UWL的变化是受环境及体内代谢等多种因素的影响,并且与其自身的生长与代谢活性更密切。     

Phosphatidylethanolamine in wheat and barley leaves under water stress

Phosphatidylethanolamine could not be detected in the leaves of less drought-tolerant varieties of wheat (S-308) and barley (BG-25) when the plants wer     

长药景天的叶龄与CAM活性

用CO_2分析。含酸量和PEP羧化酶活性测定的方法对长药景天(Sedum spectabile)光合型进行研究,其成熟叶浇水时表现为C_3型,干旱条件下转变成CAM型,但极度的干旱又使其CAM活性降低。浇水植株的幼叶PEP羧化酶活性和含酸量低,成熟叶较高。但在干旱过程中,幼叶酶活性和含酸量的增加比成熟叶更为显著,表明幼叶对水分胁迫更敏感。水分胁迫中,叶最大PEP羧化酶活性和最大含酸量在植株由下而上各叶位转移。     

噻二唑苯基脲在平贝母脱分化过程中引起的生理生化变化

平贝母(Fritillaria ussuriensis Maxim)鳞茎切块分别在含噻二唑苯基脲(TDZ)或激动素(Kin)的培养基上脱分化过程中的苯丙氨酸解氨酶、淀粉酶、吲哚乙酸氧化酶和过氧化物酶活性均增强,在外植体脱分化前达到峰值,随后下降。TDZ处理下这些酶的活性均高于Kin处理。可溶性蛋白含量的变化趋势与酶活性变化相同,只是TDZ作用下蛋白含量增加的相对水平较低。说明TDZ具有比Kin更强的细胞分裂素活性。     

NaCl胁迫下星星草幼苗MDA含量与膜透性及叶绿素荧光参数之间的关系

星星草幼苗在不同浓度NaCl胁迫处理7d后,测定了叶绿素荧光参数、MDA含量和叶片电解质外渗率。结果表明,在低浓度NaCl(小于1·2%)胁迫下,星星草幼苗叶绿体MDA含量随胁迫强度的增强而降低,而在高浓度NaCl(1·2%~2·4%)胁迫下则相反。在低浓度NaCl(小于1·2%)胁迫下,Fv/Fm(PSⅡ原初光能转化效率)、Fv/Fo(表PSⅡ潜在活性)、Fv′/Fm′(类囊体能化时PSⅡ固有效率)和qP(荧光光化学淬灭效率)随着胁迫强度的增强而增高,而在高浓度NaCl(1·2%~2·4%)胁迫下则随着胁迫强度的增强而降低;而qNP(荧光非光化学淬灭效率)和HDR(热耗散速率)却随着胁迫强度的增强而增高。ΦPSⅡ(PSⅡ实际光化学效率)在低浓度NaCl(小于0·4%)胁迫下随着胁迫强度增强而升高,在0·4%~1·6%之间迅速下降,大于1·6%时,ΦPSⅡ又迅速升高。Fv/Fm、Fv/Fo、Fv′/Fm′和qP均随着MDA含量的增高而降低,而EL(叶片电解质外渗率)、qNP和HDR在MDA含量较低的范围(0·9753~1·1901μmol·g-1FW)内均减小,在MDA含量较高的范围(1·3080~1·8518μmol·g-1FW)内,均迅速增大。ΦPSⅡ在MDA含量较低范围(0·9753~1·0953μmol·g-1FW)内时上升,但变化不大,随着MDA含量的增高(在1·1172~1·1901μmol·g-1FW)范围内迅速降低,但当MDA含量进一步增高时(在1·3080~1·8518μmol·g-1FW)范围内又迅速升高。这些结果表明,星星草幼苗的荧光参数具体的变化规律与盐胁迫强度和幼苗细胞膜的受损伤程度密切相关,即低浓度NaCl胁迫(小于1·2%)下,星星草幼苗由于活性氧的增加而发生膜脂过氧化可能主要通过体内较高活性的保护酶系统来清除,而高浓度NaCl胁迫(大于1·2%)下,星星草幼苗可能具有与其它植物不同的保护机制,即可能主要通过增加qNP(荧光非光化学淬灭效率)、HDR(热耗散速率)耗散过剩的光能和提高ΦPSⅡ增强假循环式光合磷酸化过程,消耗掉多余的能量,以保护光合器官免受过剩光能的损伤,从而减轻膜脂过氧化作用。