Effect of pre-treatment with ethanolamine on the response of Helianthus annuus L. to salt stress

The accumulation of compatible solutes is one of the strategies that plants have developed to tolerate salt stress. Proline and betaine are the main metabolites that accumulate in various species of higher plants in response to salt stress. In Helianthus annuus L., pre-treatment of seeds with ethanolamine led to enhanced seedling tolerance to conditions of saline stress during germination, as evidenced by the greater growth of pretreated seedlings (EAS group) versus untreated seedlings (S group), evaluated through such parameters as length, water and chlorophyll content. During the germination period, a considerable increase was observed in proline levels (up to 300%) in seedlings subjected to saline stress, whereas in the EAS group, the proline increment was much smaller (20%). Starting from the fourth day of germination, betaine levels in seedlings pretreated with ethanolamine and then with water (EAW group) and in EAS showed a significant increase versus C (control) and S seedlings, possibly because such a precursor promotes betaine biosynthesis. This could be responsible for the enhanced growth observed in EAS versus S seedlings, as well as for preventing the decrease in chlorophyll content in the EAS group. The accumulation of betaine seems to correlate with the greater tolerance of these seedlings against stress induced by sodium chloride.     

海水胁迫对向日葵苗期生长及矿质营养吸收特性的影响

采用砂培法,研究了海水胁迫对向日葵幼苗生长及矿质营养吸收特性的影响。结果表明,海水胁迫下,向日葵幼苗株高、茎粗、干物重明显降低。幼苗根茎叶中Cl-,茎和叶中Mg2 、叶中Na 和Ca2 含量随海水浓度的增加而增加,根茎叶中K 、全氮和全磷含量随海水浓度升高而降低,但在10%和20%海水胁迫下,向日葵体内Na 、Cl-主要集中于根和茎中,叶中较少。海水胁迫下,向日葵幼苗各部位K /Na 始终是叶部最高,根部最低,且根茎叶中SK,Na值均大于1。因此,低浓度海水胁迫下向日葵幼苗对Na 和Cl-的截流作用、海水胁迫下幼苗根部对K 强的选择性吸收以及K 向地上部的选择性运输是向日葵具有一定耐盐性的主要原因。     

Behaviour of antioxidant defense system in the adaptive response to salt stress in Helianthus annuus L. cells

A relationship between the antioxidant defense system and salt tolerance in two types of sunflower calli differing in salt sensitivity was studied. No reduction in growth occurred in the NaCl-salt-adapted cell line (T) when grown on 175 mM NaCl but growth of the salt-stressed cell line (S) was reduced by 83%. Lipid peroxidation and protein oxidation increased during acute stress of salt stressed cells at 14 and 28 d of the experiment, while salt-adapted calli (T) remained similar to non-shocked (C) values. The antioxidant defense system of callus adapted to growth under NaCl responded differently to 175 mM of salt compared with the corresponding controls under shock treatment. Salt-adapted and salt-stressed calli showed a similar pattern in GSH content at day 14 but at day 28 in S calli, GSH content was increased 100% over the non-shocked calli, while T calli returned to the initial values. In the salt-stressed calli, a general decrease in all the antioxidant enzymes studied (except for glutathione reductase and dehydroascorbate reductase activities) was observed at day 28. Except for catalase, the antioxidant enzymes were elevated constitutively in adapted calli as compared to stressed cells, when both were grown in the absence of NaCl (time 0), and remained unaltered until 28 d after the beginning of the experiment. These results suggest the involvement of an enzymatic antioxidant defense system in the adaptive response to salt stress in Helianthus annuus L. cells.     

卫星搭载向日葵种子SP2代花部变异株的研究

利用卫星搭载向日葵种子后获得的花部变异株,SP2正常株与对照株比较,结果表明：突变株筒状花的花瓣变大、增长,花药变小,而子房和花柱的变化不大。在同一个花盘中,外周花的花瓣长大,而中心部花的花瓣短小。变异株的小孢子增大。精核分化早,呈线状,是观察小孢子精核形态的好材料。     

卫星搭载向日葵种子SP_2代花部变异株的研究

利用卫星搭载向日葵种子后获得的花部变异株,SP2正常株与对照株比较,结果表明:突变株筒状花的花瓣变大、增长,花药变小,而子房和花柱的变化不大。在同一个花盘中,外周花的花瓣长大,而中心部花的花瓣短小。变异株的小孢子增大。精核分化早,呈线状,是观察小孢子精核形态的好材料。     

3个向日葵品种生长期内水分、蛋白质和总黄酮含量动态变化

本实验研究了3个向日葵品种在生长周期内茎、叶及茎叶混合样的水分、蛋白质和总黄酮含量的动态变化.结果表明:向日葵不同品种、不同生长期以及同一品种的不同部位的水分、蛋白质、总黄酮含量均存在差异.水分含量整体呈现下降趋势,且茎＞茎叶混合＞叶;蛋白质含量为叶＞茎叶混合样＞茎,其中高秆食用葵叶片中蛋白质含量为8.10g/100g...     

Involvement of an antioxidant defence system in the adaptive response to heavy metal ions in Helianthus annuus L. cells

A relationship between the antioxidant defence system and metal iontolerance in two types of sunflower callus differing in metal ion sensitivitywas studied. The antioxidant defence system of callus subjected to anadaptationtreatment of Cd(II), Al(III) and Cr(III) responded differently to 150M of each metal compared with the corresponding controls undershock treatment. The GSH/GSSG ratio remained similar to control values for thethree metal-acclimated calli and in the chromium shock treatment, decreasingmoderately in the acute treatment with cadmium and aluminum. In contrast, theAs/DAs ratio was decreased in the two different treatments for the three metalsions, but the decrease was greater with acute stress. The antioxidant enzymesresponded differently according to the metal and treatment used. In chromiumadapted callus, all antioxidant enzymes increased except for glutathionereductase. However, in the shock treatment ascorbate peroxidase activity wasdiminished with each metal ion assayed. Guaiacol peroxidase was decreased bycadmium and chromium and remained similar to control values with aluminum.Glutathione reductase was only decreased by cadmium, and superoxide dismutaseand catalase activities were less increased than in tolerant cells. Theseresults suggest the involvement of an antioxidant defence system in theadaptiveresponse to heavy metal ions in Helianthus annuus L.cells.     

Production of asymmetric somatic hybrid plants between Cichorium intybus L. and Helianthus annuus L.

In order to obtain male-sterile asymmetric somatic hybrids between chicory (Cichorium intybus L.) and a sunflower (Helianthus annuus L.) male-sterile cytoplasmic line, mesophyll chicory protoplasts inactivated with iodoacetic acid and hypocotyl sunflower protoplasts irradiated with γ-rays have been fused, using PEG and applying two different procedures. Thirty three plants were regenerated from putative hybrid calli. A cytological analysis of their root-tip cells indicated that most of them had 18 chromosomes, the same number as chicory. Through Southern hybridisation on total DNA using the maize mitochondrial specific gene probes Cox I, Cox II and Cob, three plants were identified as cytoplasmic asymmetric hybrids, as shown by hybridisation bands specific for both chicory and sunflower. One of the regenerated plants produced a novel pattern of hybridisation that was not detected in either parent. When hybridisation of total DNA was carried out with an atpA mitochondrial gene probe the same three cybrids presented both the fertile chicory fragment and the male-sterile sunflower fragment. Finally, Southern hybridisation with an ORF 522 probe, which in sunflower is co-transcribed with the atpA gene, confirmed the hybrid nature of the three plants. The morphology of the cybrids resembled the parental chicory phenotype, and at anthesis their anthers produced fewer pollen grains which could not germinate either ”in vitro” or ”in situ.” Cybrid plants grown in the field produced seeds when free-pollination occurred. Received: 26 April 2000 / Accepted: 28 August 2000     

Investigation of the limitations to photosynthesis induced by leaf water deficit in field-grown sunflower (Helianthus annuus L.)

Abstract. The diurnal cycling of leaf water potential (Ψ_leaf) in field-grown sunflower ( Helianthus annuus ) was used to investigate the cause of water deficitinduced limitation of net photosynthesis. Daily midafternoon decreases in Ψ_leaf of up to 1.5 MPa and in net photosynthesis of up to 50% were typical for irrigated sunflower during seed filling. These midafternoon values were lowered an additional 0.6 to 0.8 MPa by prolonged drought treatment. There was a nearly linear relationship between the decline in net photosynthesis and reductions in leaf conductance over the course of the day. Thus, it was unexpected to find that the low, midafternoon rates of photosynthesis were associated with the highest intercellular CO₂ concentrations. These and other observations suggest that the daily decline in photosynthesis represents a 'down regulation' of the biochemical demand for CO₂ that is coordinated with the diurnally developing need to conserve water, thus establishing a balanced limitation of photosynthesis involving both stomatal and non-stomatal factors. There were no indications that either short term (i.e. diurnal declines in Ψ_leaf) or long term (i.e. drought treatment) water deficits caused any damage or malfunctioning of photosynthesis. Rather, both the daily declines in photosynthesis and the nearly 25% decrease in leaf area induced by prolonged drought appeared to be well-controlled adaptive responses by field-grown sunflower plants to limited water availability.     

Immunofluorescent Localization of a Connexin 26-like Protein at the Surface of Mesophyll Protoplasts from Vicia faba L. and Helianthus annuus L.

Mesophyll protoplasts from three week old leaves of Helianthus annuus L. and from four week old leaves of Vicia faba L. were incubated with polyclonal, monospecific antibodies, raised against either cx 32 or cx 26 mouse liver connexin. Crossreactions were visualized by FITC-labeled anti-rabbit antibodies. Incubations with the cx 26 antibody resulted in fluorescing spots on protoplast surfaces of both plant species, indicating the presence of a polypeptide, immunologically related to the animal cx 26. A plant protein, exhibiting similarities to cx 26, would present a new member of connexin-like plant proteins. Controls, performed with preimmune serum or with the FITC-conjugate alone, were negative. Immunofluorescing spots were not obtained after incubations with the cx 32 antibody. Since the existence of a cx 32-like plant protein, associated with ultrastructures of plasmodesmata and the plasma membrane, is meanwhile established, several explanations for the failed attempt to demonstrate a cx 32 antibody labeling at protoplast surfaces are discussed.     

Modulation of inflammatory responses by diterpene acids from Helianthus annuus L

Fractionation of a petroleum ether extract of Helianthus annuus L. led to the isolation of three diterpene acids: grandiflorolic, kaurenoic and trachylobanoic acids. These compounds were studied for potential anti-inflammatory activity on the generation of inflammatory mediators in lipopolysaccharide (LPS)-activated RAW 264.7 macrophages. At non-toxic concentrations, these compounds reduced, in a concentration-dependent manner nitric oxide (NO), prostaglandin E₂ (PGE₂) and tumor necrosis factor (TNF-α) production, as well as expression of inducible nitric oxide synthase (NOS-2) and cyclooxygenase-2 (COX-2).All diterpenoids displayed significant in vivo anti-inflammatory activity and suppressed the 12-O-tetradecanoylphorbol-13-acetate (TPA)-mouse ear edema. In addition, inhibition of myeloperoxidase (MPO) activity, an index of cellular infiltration, was observed.In summary, our results suggest that the inhibition of the expression of NOS-2, COX-2 and the release of inflammatory cytokines, is responsible for the anti-inflammatory effects of the diterpenoids isolated from H. annuus L. which likely contributes to the pharmacological action of sunflower.     

向日葵(Helianthus annuus L.)对133Cs、88Sr的吸收和分布

通过盆栽试验研究了向日葵(Helianthus annuus L.)对土壤中不同处理浓度¹³³Cs和⁸⁸Sr的吸收,以及¹³³Cs和⁸⁸Sr在向日葵不同部位的分布。结果表明：随着处理浓度的增加,植物中¹³³Cs或⁸⁸Sr的含量增加。同一处理浓度下,⁸⁸Sr含量约比¹³³Cs含量高一个数量级。¹³³Cs和⁸⁸Sr在植物不同部位分布不同。根部中¹³³Cs含量高于植物的其他部位（茎、叶、花）。不同于¹³³Cs在植物中的分布,⁸⁸Sr除在根中的分布外,主要转运到了叶片。¹³³Cs和⁸⁸Sr在向日葵体内的分布与目前对放射性¹³⁷Cs和⁹⁰Sr的研究结果相似,所以¹³³Cs和⁸⁸Sr可分别预测¹³⁷Cs和⁹⁰Sr的运转。向日葵是治理大面积低放核素污染土壤的较佳植物种类。     

向日葵茎芯多糖的提取工艺优化及其体外抗肿瘤活性研究

研究了向日葵茎芯中主要活性物质多糖的提取工艺,并对此工艺进行了优化,选取的提取方法为水提醇沉法,以多糖含量作为指标,采用单因素试验研究了提取次数、原料颗粒的大小（目数）、料液比、提取时间、提取温度对向日葵茎芯多糖含量的影响。用苯酚-硫酸法测定提取液中多糖的含量,得出向日葵茎芯中多糖的最佳提取工艺条件为：提取次数2次,原料颗粒的大小（目数）60~80目,料液比（g·mL^-1）1：50,提取时间3.0 h,提取温度90℃,在最优提取条件下,多糖的提取得率为6.56%,多糖的含量为266.03 mg·g^-1。本文也对多糖的体外抗肿瘤活性进行了研究,结果表明向日葵茎芯多糖的体外抗肿瘤活性较弱。这些条件的确定为向日葵茎芯的深入研究奠定了基础。     

Relationships between root permeability to water,leaf conductance and transpiration rate in sunflower (Helianthus annuus L.) cultivars

Summary The relations between leaf conductance (g_l) transpiration rate and root permeability to water (R_p) of three sunflower (Helianthus annuus L.) cultivars grown in a controlled environment cabinet are described.No differences in transpiration rates were found but it was shown that plants with low values of R_p have active stomatal closure with favourable consequences for water use efficiency under water limiting conditions.R_p was estimated by applying hydrostatic pressure on the root system. Values of R_p per unit root volume ranged from 0.34×10^–5 to 16.75×10^–5 (s MPa^–1). There were significant inter-cultivar differences (P<0.05) in R_p and g_l and an inverse correlation between R_p and the maximum values cf g_l within cultivars.Pressure applied on the root system is proposed as a useful tool for the determination of differences in the root permeability to water amongst sunflower cultivars.     

Leaf expansion of four sunflower (Helianthus annuus L.) cultivars in relation to water deficits. II. Diurnal patterns during stress and recovery

Abstract. Leaf expansion of four sunflower cultivars ( Helianthus annuus L. cvs. Hysun 31, Havasupai, Hopi and Seneca) was monitored continuously in a growth cabinet through the final stages of a drying cycle and then throughout the first 2 days after rewatering in order to study the responses of leaf expansion to water deficits. Comparable plants were also measured throughout a diurnal cycle in a glasshouse.
In the cabinet, leaf extension was faster in the dark than in the light, but an extended dark period suppressed leaf extension. At similar leaf water potentials, the rate of leaf extension was greater in the light than in the dark, but as the osmotic potential was lower in the light than in the dark, the relationship between turgor pressure and leaf extension rate was similar in both environments. Throughout the drying and recovery cycles turgor and leaf extension rate was positively correlated: no significant differences among cultivars were observed.
In the plants grown and measured in the glasshouse, leaf expansion occurred at lower leaf water potentials in stressed than in unstressed plants, but the relationship between leaf expansion and turgor was similar in both stressed and unstressed plants as a result of a lowering of the osmotic potential in the former. Diurnal turgor maintenance resulting from osmotic adjustment was almost half that occurring during a complete drying cycle. During the day, the leaf expansion rate increased linearly with turgor pressure in all cultivars: the expansion rate per unit turgor pressure was greater in the glasshouse than in the growth cabinet. Nocturnal leaf expansion in the stressed and unstressed plants was not, however, correlated with turgor pressure.     

The effects of methyl jasmonate on sunflower (Helianthus annuus L.) seed germination and seedling development

Some effects of methyl jasmonate (Me-Ja) on sunflower (Helianthus annuus L.) seed germination and seedling development are described and compared with those of ABA. Both growth regulators have very similar action. They inhibit germination, but high concentrations of O₂ in the atmosphere suppress this inhibitory action. Depending on the concentration, Me-Ja inhibits root and hypcotyl growth, however the root is more sensitive to Me-Ja than to ABA. Me-Ja also strongly reduces oxygen uptake during germination and inhibits chlorophyll biosynthesis in isolated cotyledons.     

Plant donor tissue and isolation procedure effect on early formation of embryoids from protoplasts of Helianthus annuus L.

The effects of factors influencing sunflower protoplast isolation yield, plating efficiency (PE) and the early differentiation into embryoids (embryogenic capacity, EC) have been studied. Only hypocotyl-derived protoplasts divided. The variations of PE and EC in the various treatments did not seem to be linked to the protoplast yields. From statistical analysis of the data, we concluded that, the sunflower genotype, the age and height of seedlings, the part of hypocotyl used, the incubation time (from 6 to 16 hours) in enzymes of explants or of protoplasts alone, influenced PE but large variations were detected for EC. A comparison of the factors effecting EC suggested an origin, inside the hypocotyl, of cells able to give rise, after induction, to embryogenic protoplasts.     

Leaf responses to soil water deficits: Comparative sensitivity of leaf expansion rate and leaf conductance in field-grown sunflower (Helianthus annuus L.)

The relative importance of changes in leaf expansion rate (LER) and leaf conductance (g₁) in the control of crop transpiration depends primarily on their sensitivity to soil water deficits. The aim of this paper was to quantify the responses of LER and g₁ to soil water deficits in sunflower (Helianthus annuus L.) under conditions of moderate (spring) and high (summer) evaporative demand. Soil water content, g₁, and LER were measured in dryland (DRY) and daily-irrigated (WET) crops established on a deep sandy-loam (Typic Xerofluvent) in a Mediterranean environment. There was no difference between g₁ of DRY and WET plants (p>0.20) in contrast with a highly significant difference in LER (p<0.001). Even under the harsh conditions of the summer experiment, g₁ did not respond to water deficit in a ten-day period in which LER of DRY plants was reduced to approx. 30% of that measured in WET controls. This field study indicates that g₁ plays at most a minor role in the control of sunflower transpiration in the pre-anthesis period and confirms the importance of leaf expansion in the regulation of gas exchange of expanding canopies subjected to soil water deficits.