Plantlet Regeneration from Electrostimulated Protoplasts of Sunflower (Helianthus annuus L.)

Hypocotyl protoplasts from Helianthus annuus L. were electrically stimulated using different parameters and subsequently cultivated in agarose droplets with weekly changes of the liquid media. Macroscopic visible calli (0.1-0.3 mm) were transferred onto solid media supplemented with different concentrations of NAA, BAP, and GA₃. Colonies reaching a size of about 3 mm were isolated and further cultivated under the same conditions. Several calli originating from electrically stimulated protoplasts and especially those cultured on relative high auxin concentrations, generated somatic embryos which were characterized by a green globular shoot tip and a developing root. Later on differentiation of the shoot tip occurred on kinetin-containing MS medium leading to plantlets with stunted shoot axis. No somatic embryos were initiated in control experiments with non-stimulated protoplasts.     

Bacterial antagonists of Sunflower (Helianthus annuus L.) fungal pathogens

Bacteria isolated on nutrient agar and King's medium B from sunflower leaves, crown and roots inhibited in vitro growth of the leaf spot and wilt pathogens Alternaria helianthi, and Sclerotium rolfsii, respectively, and also the root rot pathogensRhizoctonia solani and Macrophomina phaseolina. Antagonistic bacteria from leaves were mainly actinomycetes and pigmented Gram-positive bacteria, while those from roots and crowns were identified asPseudomonas fluorescens-putida, P. maltophilia, P. cepacia, Flavobacterium odoratum andBacillus sp. In soil bioassays, when used as seed inoculum in the presence ofS. rolfsii, P. cepacia strain N24 increased significantly the percentage of seedling emergence. Bacterial strains which exhibited broad spectrum in vitro antagonistic activity were tested for colonisation of sunflower roots, when used as a seed inoculum. Good colonisers (10⁴ to 10⁶ bacteria/g root) were consistent in their ability to reduce disease and fungal wilt. A seedling having a primary root length < 5 cm with fewer lateral roots, necrosed cotyledons or crown and a wilted shoot indicated its diseased status. On an average, only 30% of seedlings were diseased when treated with the antagonistic strains, in the presence of the pathogen, while 60% of the seedlings were diseased in the presence of the pathogen alone. In microplots treated with strain N24, only 1 to 3% of the seedlings were wilted, while 14% of the seedlings were wilted in the presence of the pathogen alone. The results obtained show that bacterial antagonists of sclerotial fungi can be used as seed inocula to improve plant growth through disease suppression     

Distribution of Nitrogen during Growth of Sunflower (Helianthus annuus L.)

The accumulation, distribution and redistribution of dry matterand nitrogen is described for Helianthus annuus L. cv. Hysun21 grown on 6 mM urea in glasshouse culture. Seed dry matterand nitrogen were transferred to seedlings with net efficienciesof 40 and 86 per cent respectively. At flowering, the stem hadmost of the plant's dry matter and the leaves most of its nitrogen.About 35 per cent of the plant's nitrogen accumulated afterthree-row anthesis. The amount of protein in vegetative parts,especially leaves, declined after flowering. Concentrationsof free amino compounds also decreased during growth. Matureseeds had 38 per cent of the total plant dry weight and 68 percent of the total nitrogen. Seeds acquired 33 per cent of theirdry matter and nitrogen from redistribution from above-groundplant parts. The stem was most important for storage of carbohydrate,leaves the most important for nitrogen. Over 50 per cent ofthe nitrogen in the stem and leaves was redistributed. Plantsthat received 6 mM nitrate accumulated more dry matter thanurea-grown plants. Seeds from nitrate-grown plants were heavier(58 mg) than those of urea-grown plants (46 mg), and their percentageoil was greater (50 and 41 respectively). The amount of nitrogenper seed was the same. Little or no urea was detected in xylem sap of plants suppliedwith 5 mM urea, but it was detected in sap of plants which received25 mM. Concentrations of urea and amino compounds in the sapdecreased up the stem. Plants supplied with nitrate had mostof the nitrogen in xylem sap as NO₂^–, suggesting littlenitrate reduction in roots. Plants grown on 6 mM nitrate andchanged to high levels of urea-nitrogen for 14 days still hadhigh levels of nitrate; little nitrate remained in plants receivinglow levels of urea. When urea is applied in irrigation waterto field-grown sunflower, the nitrogen is subsequently takenup as nitrate due to rapid nitrogen transformations in the soil. Helianthus annuus L., sunflower, urea, nitrate, nitrogen transport, xylem sap, nitrogen accumulation nitrogen distribution     

Effect of Mechanical Stress on Sunflower (Helianthus annuus L.) Hypocotyl Growth

Etiolated seedlings of Sunflower (Helianthus annuus L.) weresubjected to mechanical stress by longitudinally compressingthe hypocotyl with approx. 0·05 N force (equivalent to0·025 MPa for a 1·6 mm diameter hypocotyl). Thisrelatively low compressive stress effected an increase in relativegrowth rates (RGR) of the hypocotyl for a period of 1-2 h, followingwhich RGR returned to the pretreatment rate. RGR was also increasedby an equivalent compressive stress treatment (0·025MPa) for 4 h in water or in 10^-10 mol l^-1 IAA. These resultsare discussed in the context of a possible role for mechanicallyinduced stress in the initiation and maintenance of nutationalgrowth movements.Copyright 1994, 1999 Academic Press Helianthus annuus, Sunflower, hypocotyl growth, mechanical stress, seedling growth, nutational growth movements, circumnutation     

油用向日葵主要农艺性状的遗传分析

对10个油用向日葵品种的主要农艺性状进行遗传分析的结果表明,株高、单株粒数、百粒重、盘径和单株粒重等农艺性状具有较大的遗传率,可以在早代单株选择或直接选择;出苗-现蕾、现蕾-开花、开花-成熟、皮壳率等性状的遗传率较低,应根据各性状间相关关系进行间接选择或将选择推迟到晚期世代进行。遗传变异幅度较大的性状有皮壳率、单株粒数、小区产量、单株粒重等。由于性状的遗传改良效果主要由该性状的遗传率和变异幅度及选择强度所决定,因此,在选择率确定为5%情况下,遗传改良效果较好的性状为单株粒数和单株粒重。 Abstract:The genetic analysis of main agronomic characters was conducted with 10 varieties of oil sunflower(Helianthus annuus L.).The results showed that direct selection can be carried out at early generation for characters with higher heritability such as plant height,grain number pere plant,100-grain weight,diameter of disc and grain weight per plant.For maturity and percentage of shell with lower heritability,indirect selection correlated with other characters or late generation selection can be utilized.The characters showing wide genetic variation were those as percentage of shell,grain number per plant,grain yield per plot and grain weight.Since the successful improvement of a character mainly depends on its heritability,variation of heritability and intensity of selection,we suggest that the characters which may give better genetic improvement are grain number and grain weight per plant under condition of 5% selection pressure.     

Membrane-bound Plastid Inclusions and Chloroplast Thylakoid Formation in Sunflower (Helianthus annuus L.)

The ultrastructure, distribution and frequency of membrane-boundplastid inclusions present in the epidermal cells of leavesof intact sunflower plants (Helianthus annuus L.) and in theepidermal and mesophyll cells of sunflower leaf discs culturedin darkness have been studied. These inclusions appear to bedilated thylakoids containing a granular material which, undernormal conditions, is probably involved in chloroplast membraneformation. It is suggested that this material accumulates, andinclusions form, in the chloroplasts of sunflower leaves intwo specific situations. Firstly, in the completely differentiatedcells of the epidermis where the chloroplasts, although at arelatively immature stage, have nevertheless reached a terminalstage of development. Secondly, in the mesophyll cells of youngleaves when chloroplast development has been arrested at animmature stage by a 5-day dark period. In the latter situationthe material can be remobilized if plastid development is restimulated.The plastids of sunflower leaf discs cultured in darkness containboth membrane-bound inclusions and prolamellar bodies, indicatingthat they are separate and distinct structures possibly containingdifferent membrane components. Helianthus annuus L., sunflower, chloroplast, ultrastructure, plastid inclusions, thylakoid formation     

A Quantitative Study of the Resistances to Transpirational Water Movement in Sunflower (Helianthus annuus L.)

Hydroponic sunflower plants were used in a quantitative studyof the relationship between total plant and leaf resistancesto transpirational water movement and transpiration rate. Theresults demonstrate that both resistances are flux-dependentand decline 5–6-fold during a comparable increase in transpiration.The resistance of excised leaves including the petiole was approximatelyhalf the total plant resistance. Subsequent analyses of the water potential gradients and transpirationalfluxes in whole plants permitted calculation of the magnitudeof the partial resistances imposed by roots, stem, petiole,and leaf. The root and leaf resistances were approximately 50%and 30% of the total resistance respectively. Stem and petiolarresistances were relatively small and both influenced watermovement to the upper leaves similarly. The values obtainedare compared with previous published results obtained usingdiverse experimental techniques.     

Effect of Flooding on Starch Accumulation in Chloroplasts of Sunflower (Helianthus annuus L.)

Chloroplasts in leaves of sunflower (Helianthus annuus L. cv hybrid 894) whose roots were flooded for 4 days showed an increase in the level of starch in chloroplasts when examined with the electron microscope. Starch determination showed significantly higher levels in leaves of flooded plants. Chloroplast and mitochondrial structure seemed otherwise normal.     

Water Stress in Sunflower (Helianthus annuus L.): I. Effect on Plant Development

Development of sunflower plants grown in pots under controlledconditions was monitored at frequent intervals. Two separatewater stresses, which reached a minimum of –1.7 MPa, wereimposed at specified developmental stages on two separate batchesof plants. Leaf initiation and leaf unfolding were significantlyreduced by water stress. Inflorescence primordium initiation,involucre bract formation, disc and disc floret developmentwere not affected. The mitotic index was reduced by water stressin unfolding leaves from 5 to 0.5 per cent. In other leaves,the mitotic index was reduced to a lesser extent. This reducedmitotic index helps explain reduction in leaf development. Thetime between seed germination and inflorescence primordium initiationremained relatively constant despite the reduced leaf numberassociated with water stress. The discussion evaluates the complicationsthat this may cause in the comparison of leaves in the upperhalf of the leaf profile. Helianthus annuus L., sunflower, water stress, mitotic index, leaf development     

Combined linkage and association mapping of flowering time in Sunflower (Helianthus annuus L.)

Association mapping and linkage mapping were used to identify quantitative trait loci (QTL) and/or causative mutations involved in the control of flowering time in cultivated sunflower Helianthus annuus. A panel of 384 inbred lines was phenotyped through testcrosses with two tester inbred lines across 15 location × year combinations. A recombinant inbred line (RIL) population comprising 273 lines was phenotyped both per se and through testcrosses with one or two testers in 16 location × year combinations. In the association mapping approach, kinship estimation using 5,923 single nucleotide polymorphisms was found to be the best covariate to correct for effects of panel structure. Linkage disequilibrium decay ranged from 0.08 to 0.26 cM for a threshold of 0.20, after correcting for structure effects, depending on the linkage group (LG) and the ancestry of inbred lines. A possible hitchhiking effect is hypothesized for LG10 and LG08. A total of 11 regions across 10 LGs were found to be associated with flowering time, and QTLs were mapped on 11 LGs in the RIL population. Whereas eight regions were demonstrated to be common between the two approaches, the linkage disequilibrium approach did not detect a documented QTL that was confirmed using the linkage mapping approach.     

Water Stress in Sunflower (Helianthus annuus L.) 3. Responses of Cypsela Size

Six water stress treatments were applied before, during andafter anthesis of the sunflower inflorescence. The effects ofthese stresses on leaf and inflorescence size, cypsela number,pericarp and embryo weight were examined. Water stress accelerated leaf senescence and reduced leaf number.Leaf area and inflorescence diameter were reduced in some treatments.Total cypsela weight may be related to leaf area. All stresstreatments reduced pericarp weight at all positions. Embryoweight at central positions was similarly affected. Post-anthesisstress did not affect embryo weight at peripheral positions.The effects of water stress on embryo weight may involve a criticalstage in development but this differs from that envisaged forleaves. Helianthus annuus L., sunflower, water stress, cypsela, inflorescence, embryo, pericarp     

A regeneration protocol for sunflower (Helianthus annuus L.) protoplasts

Summary Hypocotyl protoplasts of four different Helianthus annuus genotypes were cultivated for 22–28 days in agarose droplets covered with liquid medium. In the first week, supplementation of the medium with plant growth regulators was at a 0.8/1 ratio of cytokinin and auxin followed by a high auxin concentration in the second week and a cytokinin to auxin ratio of 8/1 in the third and fourth week. Following transfer onto solid medium containing cytokinin and auxin in a proportion of 40/1 morphogenic callus started to form globular structures that developed into leaf primordia. Subsequent shoot elongation and rooting were obtained on hormone free medium after dipping the cut shoots into high auxin solution. Thirteen weeks after protoplast isolation, plantlets could be transferred to the greenhouse. Shoot regeneration was obtained for all four cultivars (Florom-328, Cerflor, Euroflor, Frankasol) at different rates reflecting their regenerative potential.Abbreviations BAP 6-benzylaminopurine - 2,4-D 2,4-dichlorophenoxyacetic acid - FeNaEDTA ethylenediamine tetraacetic acid ferric sodium salt - IAA indole acetic acid - MES morpholinoethane sulfonic acid - NAA 1-naphtalene acetic acid     

Unsaturated Fatty Acid Synthesis During the Development of Isolated Sunflower (Helianthus annuus L.) Seeds

The effect of temperature on unsaturated fatty acid synthesisin developing sunflower seed embryos (Helianthus annuus L.)has been studied using isolated seeds grown in culture. Variabilitybetween individual embryos in the response to temperature wasalso investigated. Oil and dry matter accumulation in cultured embryos were similarto those of embryos allowed to develop in intact plants, andthe effect of increasing temperature in lowering the amountof linoleic acid in seed oil was reproduced in cultured embryos.The isolated seed culture system, therefore, constitutes a suitablemodel system for studies of oil synthesis in developing sunflowerembryos. The decrease in linoleic acid synthesis in response to highertemperature was detectable after only 18 day-degrees incubation,and the incorporation of labelled substrates suggests that alterationsin the fatty acid composition of seed oil in response to temperatureare produced by an effect on the desaturation of newly synthesizedoleate rather than through turnover of existing lipid. Variation in fatty acid composition between individual embryosgrown at constant temperature was considerable. The detectionof embryos with high linoleic acid levels following growth athigh temperature indicates that potential may exist for theselection of cultivars for temperature-stable fatty acid compositionin sunflower oil. Key words: Fatty acid synthesis, Helianthus annuus, Sunflower seeds     

Somatic Hybrids of Sunflower (Helianthus annuus L.) Identified at the Callus Stage by Isoenzyme Analysis

Dark grown hypocotyl protoplasts from Helianthus annuus L. cvs. Cerflor and Euroflor were electrically fused to produce somatic hybrids. Following fusion, the protoplasts were cultivated in agarose droplets for four weeks. Macroscopic visible calli (0.1-0.3 mm) were transferred onto solid medium and calli reaching a size of 3 mm were collected. Their isoenzyme patterns were analysed based on two different isoenzymes that allow discrimination between the two cultivars used for fusion. From the examined calli, about 26 % showed an isoenzyme pattern of putative binary heterokaryocytes. The isoenzyme pattern of the non-fused control revealed less than 5% of possibly chimeric colonies.     

向日葵ACC氧化酶基因(HaACO1)的克隆及表达分析

目的:克隆向日葵中的ACC氧化酶基因(HaACO1),并对其进行生物信息学分析及盐胁迫表达分析,为理解向日葵ACC氧化酶生理功能并加强对ACO基因的利用奠定基础。方法:以前期从盐胁迫的内葵杂4号根中获得的ACC氧化酶基因片段4-4-7TDF(KM823963)为基础,通过RT-PCR和5'/3'RACE技术克隆ACO基因的全长cDNA序列,利用生物信息学软件对获得的cDNA序列及编码的蛋白质序列进行分析。同时采用PCR方法克隆基因组DNA(genemic DNA,gDNA)序列,并对其进行结构分析。利用实时荧光定量PCR分析Na Cl胁迫下向日葵根、下胚轴、叶中HaACO1的表达量和不同NaCl浓度及不同胁迫时间下根中Ha ACO1的表达量。结果:Ha ACO1的cDNA序列全长为1 135bp,其开放阅读框为942bp,编码313个氨基酸。预测其分子质量和等电点分别为35.84k Da和5.13,基因登录号为KP966508。HaACO1与已报道的多种植物的ACO基因核苷酸序列及其推导的氨基酸序列有较高的相似性,分别为76%~83%和77%~88%。gDNA起始密码子至终止密码子序列长1 018bp,包含2个外显子和1个内含子,基因登录号为KP988289。实时荧光定量PCR分析表明向日葵HaACO1在不同器官及不同NaCl浓度、不同时间诱导下存在特异性表达差异。结论:获得的向日葵HaACO1是植物ACO家族成员之一,该基因应答盐胁迫具有独特的表达模式。     

A species-selective allelopathic substance from germinating sunflower (Helianthus annuus L.) seeds

From the exudate of germinating sunflower (Helianthus annuus L.) seeds was isolated a stereoisomer of diversifolide, 4, 15-dinor-3-hydroxy-1(5)-xanthene-12,8-olide (designated sundiversifolide) as determined by analysis of its IR, APCI-, ESI- and HR-MS and 13C and 1H NMR spectra. This substance inhibited shoot and root growth of cat's-eyes by about 50% at a concentration of 30 ppm. It also showed species-selective activity on the shoot and root growth of tested plants. When cat's-eyes seeds were incubated together with sunflower seeds, the cat's-eyes growth was inhibited. Furthermore, it was detected from an extract of river sand when sunflower seeds were incubated on the sand. These results indicate that sundiversifolide has an allelopathic function in sunflower plants.     

Prolyl iminopeptidase from seeds of sunflower (Helianthus annuus L.)

Prolyl iminopeptidase from sunflower seed (Helianthus annuus L.) was purified to molecular homogeneity. It is a 105-kDa heterodimer consisting of two subunits: 53 and 55 kDa. It has pI of 6.2 and optimal activity at pH 8.0–8.5 and 45–50°C. The inhibitory analysis was inconclusive about its catalytic machinery, as a significant degree of modification was not observed with any of the used diagnostic inhibitors. Its specificity is restricted to removal of N-terminal prolyl residues.     

Effects of Mineral Nutrition on Endogenous Cytokinins in Plants of Sunflower (Helianthus annuus L.)

The effects of inorganic nutrients on the levels of endogenouscytokinins in plants of sunflower (Helianthus annuusL.) grownin sand culture were studied. Low levels of nitrogen resultedin rapid decreases in the levels of cytokinins extracted fromleaves, buds, roots, and root exudates. Similar effects wereobserved with phosphorus deficiency, but the effects of potassiumdeficiency on the cytokinin content of leaves was less marked.The cytokinin content was higher in plants supplied with nitrogenas nitrate than in those supplied with ammonium sulphate orammonium nitrate. The decline in cytokinin levels in derooted shoots and detachedleaves could be reversed by supplying them with nutrient solution.Although leaves on intact plants may normally be dependent uponthe supply of cytokinins from the roots, isolated leaves havethe capacity for cytokinin production when supplied with inorganicnutrients.