Amplified fragment length polymorphism (AFLP) markers for fingerprinting of Argyranthemum frutescens cultivars

Argyranthemum frutescens is a commercially important ornamental species with extensive breeding programmes in several countries. Since it is vegetatively propagated there is a great need for tools for identification of cultivars. Vegetatively propagated species require clean-up from diseases, often performed through meristem-tip cultures. Forty-three cultivars of A. frutescens propagated by meristem-tip culture and traditional cuttings were analyzed for genetic relatedness and possible somaclonal variation using AFLP. Five primer combinations resulted in a relatively high degree of polymorphism. Ten molecular markers generated by one primer combination could distinguish between all 43 cultivars. Differences in fingerprints between meristem-tip culture and cuttings from the same cultivars were found, but the proportion of fragments being specific for either tissue culture or cuttings was relatively low. Some cultivars that did not display somaclonal variation as judged by the AFLP-fingerprints may still be genetically unstable since some morphological variation was observed in the true to type test.     

‘改良蒜’抗紫斑病变异株系的离体筛选

以‘改良蒜’品种带蒜瓣基部的茎盘为外植体,在含有不同浓度大蒜紫斑病菌粗毒素的MS培养基上采取分步筛选法筛选大蒜抗病变异系,并诱导形成小鳞茎;对小鳞茎繁殖的幼苗叶面喷施病菌粗毒素进行抗病性鉴定。结果表明,大蒜紫斑病菌粗毒素对‘改良蒜’愈伤组织的诱导有显著抑制作用,粗毒素浓度越高,抑制作用越强,抗病愈伤组织诱导的适宜病菌粗毒素浓度为30%;在粗毒素浓度10%、20%和30%的培养基上依次分步培养筛选获得了抗紫斑病变异系。粗毒素接种抗性鉴定表明,抗性系幼苗的抗病性比对照增强。     

体细胞无性系变异在枣育种中的应用展望

在枣组织与细胞培养过程中,体细胞无性系变异广泛存在,这为枣的品种改良和新品种选育提供了一个新的途径。各种人工诱导体细胞无性系变异方法的成功运用,使得枣育种的效率更高、可控性更强。现对体细胞无性系变异在枣育种方面的应用研究进展进行了综述,并通过对有关文献的分析,提出一些极具研究可行性的新方向;最后讨论了体细胞无性系变异在枣育种中存在的问题。     

树状月季培育技术及园林应用

树状月季作为一个园艺栽培类型,具有其他类型不具备的优点和特色,从培育、修剪、病虫害防治等方面总结树状月季的培养技术,以期为树状月季在园林绿化中的应用提供参考。     

大岩桐组织培养研究进展

从大岩桐的再生途径、再生过程、培养基配方以及再生过程中出现的褐变、休眠、体细胞突变等对大岩桐组织培养的研究现状进行了回顾,并探讨了存在的主要问题及发展趋势,以期为今后的深入研究提供参考.     

An empirical model to simulate sodium absorption in roses growing in a hydroponic system

Modelling nutrient absorption can contribute to the management of hi-tech cultivation systems in greenhouse horticultural production. Nevertheless, previous studies to understand the kinetics of nutrient absorption, rarely take into consideration the accumulation of salt ions in the nutrient solution. In this project we develop and validate an empirical model for sodium uptake concentration in hydroponic rose (Rosa spp. cv. Kardinal) production. Model development and validation was conducted using a series of experiments in both greenhouse and growth chamber conditions. The model framework takes into account plant developmental stage and external sodium concentration. While model calibration data were collected at levels of sodium up to 40 mol m³ NaCl as root environment salt concentration, model validation was carried out at lower ranges.The proposed model not only shows a high predictive capability, but also provides useful output parameters such as electrical conductivity, which is the main parameter currently monitored for managing nutrient solution in greenhouse cultivation. Incorporated as part of a larger DSS, our model can be used to improve nutrient solution management in production regions that do not have economically valid alternatives other than the use of poor quality (saline) irrigation water.     

Effect of carbohydrates on in vitro low-temperature storage of shoot cultures of apricot

Procedures for cold storage of in vitro cultures can delay subculturing, reducing production costs and risks of contamination and somaclonal variation. The present work investigates the effects of media with sorbitol (116.8 mM, medium SO) or sucrose (58.4 mM) alone (medium SU), or the latter in combination with mannitol (58.4 mM, medium M) on 7-month storage at 5 °C of apricot shoots, cv San Castrese and Boreale. Shoots in SO survived in lower percentages and grew less than in the other treatments during storage, and died in large numbers after transfer to standard culture conditions. In comparison to other treatments, survival was 100% in the presence of M and both shoot weight and number of surviving proliferated axillary shoots was increased. Moreover, M improved regrowth compared to SU under standard culture conditions. The SOD and CAT activity confirmed the higher stress of shoots stored in SO than controls, and in contrast, the low stress of shoots in M.     

Detection of somaclonal variation in micro-propagated Echinacea purpurea using AFLP marker

This study used amplified fragment length polymorphism (AFLP) analysis to assess genetic fidelity between primary regenerants of Echinacea purpurea derived from leaf organogenesis and their donor plants. A total of 40 regenerants and 5 donors (T6-28-0, T3-23-0, T5-9-0, T2-15-0 and D7-4-0) were subjected to AFLP analysis using eight primer pairs. The results indicated that a total of 3805 scorable fragments were observed, of which 301 (9.40%) were polymorphic among the tested regenerants and donors probed with eight primer pairs. The percentage of polymorphic fragments within five donor groups averaged from 1.6% to 20.6%. Jaccard's similarity coefficients among regenerants and donors averaged from 0.9508 to 0.9935. However, only two regenerants (T2-15-2 and T2-15-3) had Jaccard's similarity coefficient value of 1 as comparing to their donor, thus they were true-to-type to their donor T2-15-0. It appears that AFLP is a sensitive and reliable molecular marker to detect possible somaclonal variation in micro-propagation system of E. purpurea. In vitro culture-induced somaclonal variation occurs in primary regenerants of E. purpurea derived from leaf organogenesis, though some of regenerants have genetic similarity greater than 0.99 in comparison with their donors.     

Genetic analysis of Tunisian fig (Ficus carica L.) cultivars using amplified fragment length polymorphism (AFLP) markers

Genetic diversity of forty fig cultivars collected from five regions in Tunisia was investigated using amplified fragment length polymorphism (AFLP). A total of 342 reproducible bands amplified with six AFLP primer combinations were obtained. The high percentage of polymorphic bands (%PB) of 97.5 and the resolving power (Rp) collective rate value of 143 were scored. In addition, the polymorphism information content (PIC) values varied from 0.61 to 0.87 with an average of 0.77. Although cluster (UPGMA) and principal components analyses indicate that the cultivars’ clustering made independently both from the geographical origin, horticultural classifications and/or from the sex of trees. In addition, the observed variation suggests considerable differentiation among fig cultivars. The present data supports the common origin of the fig cultivars. Analysis of molecular variance (AMOVA) revealed that average Φ_ST value overall loci was 0.026, and the overall distribution pattern of molecular variation indicated that about 97.43% of the total variance was accounted by the within-region variance component. The remaining 2.5% (P < 0.001) of the variation was founded among cultivars of the prospected regions. Our results proved that AFLP markers are useful for germplasm discrimination as well as for investigation of fig patterns variation. The information may be useful to define conservation management program.     

Micropropagation of orchids: A review on the potential of different explants

Orchids are among the most diverse of the flowering plant families, with over 800 described genera and 25,000 species. Orchids are prized for their beautiful long lasting flowers exhibiting an incredible range of diversity in size, shape and colour. Today growing orchids is more than just a hobby, it is an international business covering around 8% of the world floriculture trade and has the potential to alter the economic landscape of a country. Large-scale multiplication of exquisite and rare hybrids using tissue culture techniques has helped orchids occupy a position as one of the top ten cut flowers. As orchids are outbreeders, their propagation using seeds leads to the production of heterozygous plants. Hence, protocols providing regeneration from various vegetative parts of the plants are needed. Though orchid micropropagation has shown spectacular development in the recent years, the wide spread use of micropropagation is believed to be still limited due to problems like exudation of phenolics from explants, transplantation to field, somaclonal variation etc. We endeavour to include the major investigations on explant-based orchid tissue culture starting from the pioneering works of Rotor [Rotor, G., 1949. A method of vegetative propagation of Phalaenopsis species and hybrids. Am. Orchid Soc. Bull. 18, 738–739] followed by Morel [Morel, G., 1960. Producing virus-free cymbidiums. Am. Orchid Soc. Bull. 29, 495–497] and Wimber [Wimber, D.E., 1963. Clonal multiplication of cymbidiums through tissue culture of the shoot meristem. Am. Orchid Soc. Bull. 32, 105–107] to date.     

Molecular characterization and analysis of somaclonal variation in chrysanthemum cultivars using RAPD markers

Molecular characterization using RAPD analysis was carried out in eight cut flowers and two pot plant cultivars of chrysanthemum. Three of them (‘Refocus’, ‘Red Reagan’, and ‘Sheena Select’) were established in vitro and the occurrence of somaclonal variation was studied using the same molecular technique. Two induction media (MS + 0.1 mg l⁻¹ NAA + 0.1 mg l⁻¹ BA, and MS + 2.0 mg l⁻¹ IAA + 0.5 mg l⁻¹ Kinetin), and two proliferation media (MS + 0.1 mg l⁻¹ NAA + 0.2 mg l⁻¹ BA, and MS + 4.0 mg l⁻¹ IAA + 2.0 mg l⁻¹ Kinetin) were employed in order to evaluate the effect of the medium composition in the shoots’ stability. Likewise, the effect of the culture age was considered in assessing genetic stability. Monthly subcultures were carried out, identifying the origin and history of the shoots, throughout a nine-month proliferation period followed by acclimatization. Molecular markers were obtained in every subculture cycle and from the acclimatized plants. Only one shoot from the 7th subculture of the cultivar ‘Refocus’ showed a different band pattern. The use of RAPD for chrysanthemum cultivar characterization and somaclonal variation detection is discussed.     

Response of young hydroponically grown tomato plants to phenolic acids

Phenolic acids—excreted both as root exudates and by microorganisms—are of interest in cultivation systems of different horticultural crops since they have been claimed to accumulate in closed hydroponic growing systems. The aim of the present investigation was to assess the phytotoxic effects when hydroponically grown tomato plants are exposed to phenolic acids in the root environment. The tomato plants were grown in static aerated culture and exposed to benzoic, caffeic, chlorogenic, ferulic, p-hydroxybenzoic, salicylic and vanillic acid at concentrations of 50, 100, 150, 200 and 400 μM in the fresh nutrient solution. The highest concentration of all tested compounds significantly reduced fresh and dry weights. Salicylic and ferulic acid affected plants already at 150 and 200 μM while effects were less pronounced for p-hydroxybenzoic and chlorogenic acid. Chlorophyll fluorescence analysis did not result in any significant difference between any of the tested acids or concentrations. No clear dose-related pattern was obtained with respect to number of leaves and plant length. Visual assessment showed that the most deleterious effects appeared on the roots, which were discoloured and/or had slimy coatings when exposed to the phenolic acids. The uptake of several mineral nutrients was influenced at the highest concentration of all studied compounds. Significantly more bacteria were enumerated in the nutrient solution treated with phenolic acids compared to the controls. Most of the phenolic acids were degraded after 2 days during the start of the trial and within 1 day at the end of the trial. Concentrations phytotoxic to small tomato plants were 1000-fold higher than the natural concentrations measured before. Instead of potentially harmful, the relevance of certain phenolic acids as antimicrobial substances should be considered.     

荸荠新品种桂蹄2号的选育

桂蹄2号是以广州番禺地方荸荠品种为材料,通过组织培养产生体细胞无性系变异,在变异群体中筛选优良变异单株,采用组培技术培育而成的荸荠新品种。以组培苗作为生产种苗,4月中下旬～5月初育苗,育苗期25～30 d（天）,大田繁苗期约50 d（天）,繁殖系数可达20倍|大田生育期约140 d（天）,株高95～105 cm,球茎扁圆形,脐微凹,横径3.5～5.5 cm,纵径2.5～3.0 cm,平均单球茎质量26 g,最大可达50 g,芽粗,皮稍厚,深红色,较耐贮运,每667 m2球茎产量2 500～3 500 kg,适宜在广西地区种植。     

甜叶菊组织培养研究进展

从无菌繁殖体系、培养基和培养条件的选择、愈伤组织的诱导与分化、芽分化和继代增殖培养、生根培养及组培苗的移栽等方面综述了甜叶菊组织培养方面的研究。并提出了甜叶菊组织培养的研究方向。     

Isolation of arbuscular mycorrhizal fungi and Azotobacter chroococcum from local litchi orchards and evaluation of their activity in the air-layers system

Soil samples were collected from rhizosphere of litchi-growing areas of North-Western Himalayan Region (NWHR) of India, for finding qualitative and quantitative differences in arbuscular mycorrhizal (AM) fungi and Azotobacter chroococcum. These samples were taken from plants being grown in different cultivation types namely, weed control with weedicides or tillage; orchard floor either clear or with cover crops; intercropping with cereals and legumes. Qualitative and quantitative differences were noticed with different cultivation types and a marked reduction in the AM fungi was observed in orchards where chemicals were used for weed control and intensive farming system was used on the orchard floor. AM fungi were generally abundant in the soils with range pH 5.5–6.6. Among different AM fungi retrieved from the soils, Glomus spp. was most dominant. Fifteen AM fungal species were isolated, identified and characterized and along with their ability to colonize the roots. In the soil samples, a marked variation in viable bacterial count of A. chroococcum was also noticed due to varied physico-chemical characteristics of the orchard soils. The changes in AM fungal species composition can be attributed to changes in soil chemical properties resulting from cultural practices such as ploughing, application of chemical fertilizers and weedicides. An experiment was also conducted to study the comparative efficacy of four dominant and frequently occurring indigenous AM species namely, Glomus fasciculatum (Thaxter sensu Gerdemann), G. magnicaulis (Hall), G. mosseae (Nicol. & Gerd.), Gigaspora heterogamma (Nicol. & Gerd.) and two A. chroococcum strains viz., AZ₁ and AZ₂ singly and in dual combination to evaluate their effect in air-layers system. Dual inoculation of G. fasciculatum and AZ₁ increased total root length of air-layered shoots by 81.39% over uninoculated control. These studies indicated that indigenously isolated AM fungal species and A. chroococcum strains can be used for air-layering for better adaptation under specific agro-climatic and ecological zone conditions.     

Characterization for yield, fruit quality, and molecular profiles of lemon genotypes tolerant to ‘mal secco’ disease

‘Mal secco’ is a serious disease of lemon and other citrus species, reduces lemon production, and limits the use of susceptible cultivars especially in the Mediterranean countries, against which there is no effective management system to control the disease. The objective of this study was to determine yield efficiency, tree and fruit characters, and molecular profiles of the selected promising genotypes in lemon breeding program to develop ‘mal secco’ tolerant lemon cultivars. After 4 years of evaluation, ‘Tuzcu 894’, a progeny of ‘Finike Yerli Yuvarlak’ and ‘Kutdiken’, was designated as promising genotype with high yield, fruit weight, juice content and low seed number contrary to ‘Kutdiken’ as control. ‘Tuzcu 8911’ was suitable for dense planting having the highest yield in CV. In addition, these two promising genotypes survived after many years being subjected to artificial and natural P. tracheiphila infections and harsh winter temperatures, which were attractive to the citrus industry. Molecular analysis, as assessed with 11 inter-simple sequence repeats (ISSR) primers, indicated that ‘Tuzcu 09 Aklimon’ and its selections, ‘Tuzcu 896’, ‘Tuzcu 897’ and ‘Tuzcu 898’, were distinct from the other genotypes with similarity value of 0.82. Genetic variation among the other lemon genotypes was low and some of the genotypes were identical. It was concluded that variations in the agronomical characters are mainly due to mutations.     

Biofertilizers improve plant growth,fruit yield,nutrition, metabolism and rhizosphere enzyme activities of Pomegranate (Punica granatum L.) in Indian Thar Desert

Production of horticultural crops has undergone enormous change in recent years due to development of innovative technologies including integrated nutrient management practices using biofertilizers. The present study represents the positive response of biofertilizers in nursery seedlings followed by their transplantation in harsh field conditions of Indian Thar Desert. Nursery and field experiments were carried out to assess the effectiveness of selected N₂-fixing bacteria and AM fungi alone or in combination, on the growth and biomass production of Punica granatum. In both experiments, the combined treatment of Azotobacter chroococcum and Glomus mosseae was found to be the most effective. Besides enhancing the rhizosphere microbial activity and concentration of various metabolites and nutrients, these bioinoculants helped in better establishment of pomegranate plants under field conditions. A significant improvement in the plant height, plant canopy, pruned material and fruit yield was evident in 5-year-old pomegranate plants in field conditions. In view of the above results, use of biofertilizer technology may be adopted for the establishment and development of other horticultural plant species in arid regions.     

Morphological development in Brassica oleracea is modulated by in vivo treatment with 5-azacytidine

Summary

Treatment with the demethylating agent 5-azacytidine induced a range of developmental changes at high frequency in Brassica oleracea vars. botrytis, italic and alboglabra. The spectrum of morphological variation was similar to that previously observed in Brassica, either as somaclonal variation as a result of tissue culture, or as a result of mutation with nitroso-N-methylurea. Where floral development permitted, inheritance of developmental variants was demonstrated to the M₂ generation. The role of methylation in determining the development and apparent genetic diversity within Brassica oleracea is discussed.     

Integration of invasion ecology theories into the analysis of designed plant communities: a case study in Southern Germany

Theories regarding the establishment and persistence of self-naturalising alien species can help in interpreting these processes in designed plant communities with their combination of exotic species and native plant communities. Thus, they may provide a theoretical basis for this kind of landscape design. A case study investigated the influence of plant community conditions (invasibility), species-specific traits (invasiveness), and gap diameter size on the establishment of selected North American prairie forbs in Central European horticultural meadows. Experimental sites were located in Freising, Bavaria. Introduced forbs included Aster laevis, Aster novae-angliae, Aster x salignus, and Aster x versicolor. Establishment success was measured as survival rate and total aboveground dry biomass. Invasibility of the investigated horticultural meadows was strongly related to resource availability, as most influences of plant community traits could ultimately be attributed to this factor. Leaf area and specific leaf area above canopy height of the resident meadow species appear to be the traits that best explained differences in establishment success of the Asters. Gap size influenced species performance mainly on the less productive site, again due to higher availability of resources in the larger gaps. These results are consistent with findings of studies on self-naturalising alien species. By applying this interdisciplinary approach, valuable insights in the functioning of designed plant communities could be gained. Horticultural meadows can be one important tool in designing the highly dynamic urban landscape. In choosing suitable sites, resource availability should be strongly considered.     

Improving the micropropagation efficiency of hybrid Dendrobium orchids with chitosan

The appropriate chitosan types and concentrations for enhancing the in vitro micropropagation of Dendrobium ‘Eiskul’ were studied using 70, 80 and 90% N-deacetylated polymeric (P-70, P-80 and P-90) and oligomeric (O-70, O-80 and O-90) forms of crab (Portunus pelagicus) chitosan. For the initial protocorm-like body (PLB) multiplication, the application of 10 mg/L of P-70 or 20 mg/L of P-90 was optimal, although 10 mg/L of P-80 and O-70 were also effective, and attained maximal PLB replication rates without increasing the detectable levels of somaclonal variation. However, during PLB-shoot induction, 10 or 20 mg/L of O-80 was the most appropriate chitosan and also induced further PLB formation. For plantlet regeneration, the addition of 10 mg/L of O-80 or P-80 gave the best quantity and quality, respectively, of plantlets. Finally, 20 mg/L of P-70 chitosan as a supplement during exflasking enhanced both the survival rate and the growth of the plantlets at one month after exflasking. Together, these data reveal a potentially beneficial and applicable protocol for commercial orchid micropropagation.