29个香蕉基因型遗传多样性的SRAP分析

采用SRAP分子标记技术对29个香蕉品种(系)的多样性进行研究,结果显示,64对SRAP引物中筛选出25个多态性较高的引物组合,共扩增出324条条带;UPGAM聚类图显示所有供试的29个香蕉品种(系)可分为2个类群且与基因型相一致;实验结果与形态、农艺性状标记分类基本一致。研究表明,SRAP技术可有效运用于香蕉基因型的遗传和育种研究。     

Improved Technique for Rapid and Non-Destructive In Vitro Differentiation between Resistant and Susceptible Banana Clones of Fusarium Oxysporum f. sp. Cubense

Culture filtrates of Fusarium oxysporum f. sp. cubense were applied to field-grown banana leaves of susceptible and resistant clones. The difference in leaf lesions, measured after 48 h, varied from 13 to 51 mm2 depending on the composition of the growth medium.     

Influence of Liquid Pulse Treatment with Growth Regulators on in vitro Propagation of Banana (Musa spp. AAA)

The effect of liquid pulse treatment of growth regulators on in vitro propagation of banana (Musa spp. AAA) was studied. Optimal shoot proliferation rates were achieved due to the pulse treatment of 6-benzylaminopurine (BA) and kinetin combination (1:1) at the concentration of 50 mg l^–1 for 60 min. Similarly high frequency of root induction was obtained due to pulse treatment with a NAA and IBA combination (1:1) at the concentration of 100 mg l^–1 for 60 min.     

香蕉叶片发育过程中不同甲酯化程度果胶的变化

采用免疫荧光标记技术,利用5种识别不同甲酯化程度聚半乳糖醛酸(HGs)果胶及香蕉果胶甲酯酶(PME)的单克隆抗体,对不同株龄香蕉叶片中PME及不同甲酯化程度的HGs定位、相对含量以及PME活性的变化进行分析,为探讨HGs和PME在香蕉生长发育及抵抗逆境过程中的功能和生理机制奠定基础。结果显示:(1)PME主要在组培苗的叶肉和保卫细胞中表达,其表达量及其酶的活性均随着香蕉株龄的增长而呈现下降趋势。(2)叶肉细胞也是各类不同甲酯化程度HGs的主要分布区域,其含量随着香蕉株龄的增长有不同程度的下降,但不同HGs在叶肉细胞中的含量以及在表皮、保卫细胞及叶脉中的分布模式不尽相同,保卫细胞中HGs的甲酯化程度较高。研究表明,香蕉的叶肉细胞是PME及这5种不同甲酯化程度HGs的主要分布场所,且这些HGs在香蕉发育过程中的含量变化趋势与PME相似。     

Field evaluation of micropropagated bananas derived from plants containing Banana Bunchy-Top Virus

Micropropagated bananas derived from Banana Bunchy-Top Virus (BBTV) infected plants, but displaying no symptoms of the disease, were established in the field. They were grown for three years and produced a plant crop and ratoon crops. No disease symptoms were observed. There was uncertainty as to whether

Protoplast Fusion in Banana (<Emphasis Type="Italic">Musa</Emphasis> spp.): Comparison of Chemical (PEG: Polyethylene Glycol) and Electrical Procedure

Optimization of protoplast fusion parameters is a prerequisite for the establishment of somatic fusion technology for banana breeding. In the present investigations, we compared the most frequently used fusion methods: the electrofusion technique and chemical procedure (polyethylene glycol). With regard to frequency of binary fusion, protoplast fusion with the fusogen polyethylene glycol was best. Conversely, electric fusion was found to be better with respect to mitotic activities, somatic embryogenesis and plantlet regeneration rate.     

Genetic stability of three economically important micropropagated banana (Musa spp.) cultivars of lower Indo-Gangetic plains, as assessed by RAPD and ISSR markers

An efficient micropropagation protocol produced large number of plants of the three elite banana (Musa spp.) cultivars Robusta (AAA), Giant Governor (AAA) and Martaman (AAB) from shoot tip meristem. The genetic relationships and fidelity among the cultivars and micropropagated plants as assessed by random amplified polymorphic DNA (RAPD) and inter-simple sequence repeat (ISSR) markers, revealed three somaclonal variants from Robusta and three from Giant Governor. A total of 5330 RAPD and 2741 ISSR fragments were generated with 21 RAPD and 12 ISSR primers in micropropagated plants. The percentage of polymorphic loci by RAPD and ISSR were found to be 1.75, 5.08 in Robusta and 0.83, 5.0 in Giant Governor respectively. Among the two marker systems used, ISSR fingerprinting detected more polymorphism than RAPD in Robusta and Giant Governor with most of the primers showing similar fingerprinting profile, whereas Martaman revealed complete genetic stability.     

Restart of Lignification in Micropropagated Walnut Shoots Coincides with Rooting Induction

The lignin content of walnut shoots did not change during in vitro shoot multiplication. Lignin content started to increase as soon as shoots were passed to a rooting medium with auxin. Exogenous auxin (applied for rooting) caused a transient elevation of the endogenous free indoleacetic acid (IAA) content with a simultaneous decrease of peroxidase activity. These events typically marked the completion of the rooting inductive phase (before any visible histological event, that is before the cell divisions beginning the rooting initiation phase). This meant that either the given exogenous auxin or the endogenous IAA has served as signal for the stimulation of lignification. Continued increase of lignification in the shoots required completion of root formation; this increase indeed was slown down when root emergence did not occur. It was further shown that lignification varied conversely to the content of the soluble phenol content, itself apparently being related to the activity of phenylalanine ammonia-lyase activity. This revised version was published online in July 2006 with corrections to the Cover Date.     

Esterase electrophoretic analysis to distinguish isolates between Bipolaris spp. and Drechslera tritici-repentis from wheat

Diseases caused in wheat by Bipolaris sorokiniana and Drechslera tritici-repentis have led to considerable yield and production losses. In wheat seeds another isolate has recently been identified, resembling Bipolaris bicolor. The objective of the present trial was to differentiate and identify isolates of these fungi based on electrophoretic analyses and morphology. Esterase electrophoresis enabled the differentiation between Drechslera sp. and Bipolaris sp. isolates. In relation to morphology, conidia from D. tritici-repentis isolates were significantly longer than the isolates of B. sorokiniana. Bipolaris bicolor isolates, on the other hand, presented wider conidia than those of D. tritici-repentis and B. sorokiniana.     

An Assessment of Genetic Integrity of Micropropagated Plants of Plumbago Zeylanica by RAPD Markers

Clones of Plumbago zeylanica were micropropagated using nodal culture. The application of random amplified polymorphic DNA (RAPD) in assessing the genetic integrity of the micropropagated plants was evaluated by polymerase chain reaction. Twenty arbitrary decamers were used to amplify genomic DNA from in vitro and in vivo plant material to assess the genetic fidelity. All RAPD profiles from micro-propagated plants were monomorphic and similar to those of field grown mother plants. No polymorphism was detected within the micropropagated plants.     

Xenopus Embryos as a Model to Study the Genetic Mechanisms of Brain Development

The review considers the advantages of Xenopus embryos as an experimental model to study the molecular-genetic mechanisms of embryo development. The results are described that were obtained with this model in studies on the early brain development within the framework of the Russian program Human Genome.     

Noctiluca scintillans may act as a vector of toxigenic microalgae

Noctiluca scintillans food vacuoles containing toxigenic microalgae of the genera Dinophysis and Pseudo-nitzschia are reported in samples from the Galician Rías Baixas (NW Spain). N. scintillans may play an important role in the population dynamics of toxigenic microalgae blooms, and may act as a vector of phycotoxins to higher trophic levels. The harmful effects of Noctiluca in natural shellfish beds and/or aquaculture sites may be magnified if cells are loaded with toxigenic microalgal prey.     

Silicon Isotopic Fractionation by Banana (Musa spp.) Grown in a Continuous Nutrient Flow Device

The determination of the plant-induced Si-isotopic fractionation is a promising tool to better quantify their role in the continental Si cycle. Si-isotopic signatures of the different banana plant parts and Si source were measured, providing the isotopic fractionation factor between plant and source. Banana plantlets (Musa acuminata Colla, cv Grande Naine) were grown in hydroponics at variable Si supplies (0.08, 0.42, 0.83 and 1.66 mM Si). Si-isotopic compositions were determined on a multicollector plasma source mass spectrometer (MC-ICP-MS) operating in dry plasma mode. Results are expressed as δ²⁹Si relative to the NBS28 standard, with an average precision of ± 0.08‰ (±2σ_D). The fractionation factor ²⁹ε between bulk banana plantlets and source solution is −0.40 ± 0.11‰. This confirms that plants fractionate Si isotopes by depleting the source solution in ²⁸Si. The intra-plant fractionation Δ²⁹Si between roots and shoots amounts to −0.21 ± 0.08‰. Si-isotopic compositions of the various plant parts indicate that heavy isotopes discrimination occurs at three levels in the plant (at the root epidermis, for xylem loading and for xylem unloading). At each step, preferential crossing of light isotopes leaves a heavier solution, and produces a lighter solution. Si-isotopic fractionation processes are further discussed in relation with Si uptake and transport in plants. These findings have important implications on the study of continental Si cycle.     

Number and Accuracy of T-DNA Insertions in Transgenic Banana (Musa spp.) Plants Characterized by an Improved Anchored PCR Technique

Nineteen transgenic banana plants, produced via Agrobacterium-mediated transformation, were analyzed for the integration of T-DNA border regions using an improved anchored PCR technique. The method described is a relatively fast, three-step procedure (restriction digestion of genomic DNA, ligation of ‘vectorette’-type adaptors, and a single round of suppression PCR) for the amplification of specific T-DNA border-containing genomic fragments. Most transgenic plants carried a low number of inserts and the method was suitable for a detailed characterization of the integration events, including T-DNA border integrity as well as the insertion of non-T-DNA vector sequences, which occurred in 26% of the plants. Furthermore, the particular band pattern generated by four enzyme/primer combinations for each individual plant served as a fingerprint, allowing the identification of plants representing identical transformation events. Genomic Southern hybridization and nucleotide sequence analysis of amplification products confirmed the data obtained by anchored PCR. Sequencing of seven right or left border junction regions revealed different T-DNA processing events for each plant, indicating a relatively low frequency of precisely nicked T-DNA integration among the plants studied.     

Analysis of aMusa spp. somaclonal variant resistant to yellow Sigatoka

Somaclonal variant CIEN BTA-03 resistant to yellow Sigatoka was obtained from a susceptible banana clone (Williams clone), by increasing the production of adventitious buds using 6-Belcilaminopurine at high concentrations. This somaclone has exhibited yellow Sigatoka resistance in the field for five consecutive years of asexual reproduction. We used RAPD markers to generate characteristic “fingerprints” for each probe, concluding that they are reliable tools for evaluating the genetic variability ofMusa regenerants obtained byin vitro culture.     

Adventitious shoot formation is not inherent to micropropagation of banana as it is in maize

Despite their similar morphology, banana and maize shoot tips responded strikingly different with respect to the in vitro formation of homogeneous multiple shoot clusters. While up to 50 small shoots per maize explant could be induced within 1 month, zero to one additional shoot formed starting from a banana shoot tip. Subsequently, banana shoot tips were subjected to different combinations of five cytokinins (0–100 μM) and five auxins (0–5 μM). The cytokinins thidiazuron and benzylaminopurine stimulated multiplication to a higher extent compared to zeatin, kinetin and isopentenyl adenine. The addition of indoleacetic acid, naphthalene acetic acid or indolebutyric acid to cytokinin containing medium did not affect the in vitro response. In contrast, 2,4-dichlorophenoxyacetic acid (1 and 5 μM) and a higher concentration of picloram (5 μM) had a detrimental effect on shoot formation and resulted in explant death and globule development. When small (0.1 cm) shoot tips were grown on cytokinin medium without an auxin source, the average number of shoots was generally two to three times lower compared to bigger (0.5 cm) shoot tips. Based on our experience in maize and this large-scale study with banana shoot tips, we conclude that banana is extremely recalcitrant towards adventitious shoot formation. This recalcitrance could not be overcome by any of the 173 different plant growth regulator combinations tested. In vitro multiplication of banana thus appears solely restricted to axillary shoot formation.     

The Effect of Pseudomonas fluorescens and Fusarium oxysporum f.sp. cubense on Induction of Defense Enzymes and Phenolics in Banana

The effect of Pseudomonas fluorescens treatment and Fusarium oxysporum f. sp. cubense inoculation on induction of phenylalanine ammonia-lyase (PAL), peroxidase (POX), chitinase, -1,3-glucanase and accumulation of phenolics in banana (Musa sp.) was studied. When banana roots were treated with P. fluorescens strain Pf10, a two-fold increase in phenolic content in leaf tissues was recorded 3 – 6 d after treatment. Challenge inoculation with F. oxysporum, the wilt pathogen, steeply increased the phenolic content in P. fluorescens-treated banana plants. Significant increase in POX activity was detected 6 – 9 d after P. fluorescens treatment. PAL, chitinase and -1,3-glucanase activities increased significantly from 3 d after P. fluorescens treatment and reached the maximum 6 d after treatment. Challenge inoculation with F. oxysporum further increased the enzyme activities. These results suggest that the enhanced activities of defense enzymes and elevated content of phenolics may contribute to bioprotection of banana plants against F. oxysporum.     

Aggressiveness and Damage Potential of Central American and Caribbean Populations of Radopholus spp. in Banana

Monoxenic cultures of burrowing nematode populations extracted from banana roots from Belize, Guatemala, Honduras, and Costa Rica were established on carrot discs. Cultures of Radopholus spp. were also obtained from Florida, Puerto Rico, Dominican Republic, and Ivory Coast. The aggressiveness (defined as reproductive fitness and root necrosis) of these populations was evaluated by inoculating banana plants (Musa AAA, cv. Grande Naine) with 200 nematodes/plant. Banana plants produced by tissue culture were grown in 0.4-liter styrofoam cups, containing a 1:1 mix of a coarse and a fine sand, at ca. 27 °C and 80% RH. Banana plants were acclimated and allowed to grow for 4 weeks prior to inoculation. Plant height, fresh shoot and root weights, root necrosis, and nematode population densities were determined 8 weeks after inoculation. Burrowing-nematode populations varied in aggressiveness, and their reproductive fitness was generally related to damage reported in the field. Plant height and fresh shoot and root weight did not reflect damage caused by nematodes under our experimental conditions. Necrosis of primary roots was closely related to the reproductive fitness of the nematode populations. Variation in aggressiveness among nematode populations followed a similar trend in the two susceptible hosts tested, Grande Naine and Pisang mas. All nematode populations had a low reproductive factor (Rf ≤2.5) in the resistant host except for the Ivory Coast population which had a moderate reproductive factor (Rf ≤ 5) on Pisang Jari Buaya. This is the first report of a burrowing nematode population parasitizing this important source of resistance to R. similis.     

Plant regeneration from cultured protoplasts of the cooking banana cv. Bluggoe (Musa spp., ABB group)

Summary Suspensions of embryogenic cells of a triploid banana (Musa spp., cv. Bluggoe) were initiated from the uppermost part of meristematic buds, and used as protoplast source. After 20 weeks in culture, the suspension contained a mixture of globular structures or globules and embryogenic cell clusters, as well as single cells. Two types of protoplasts were obtained from embryogenic suspension culture: small (20–30 m) and larger (30–50 m) protoplasts with a dense cytoplasm and large starch grains respectively. The small protoplasts probably originated from embryogenic cell clusters, and also from pseudocambial cells of globules, while larger protoplasts were probably released from oval starchy cells and those of the globule peripheral area. In co-culture with a suitable feeder, consisting of suspensions of diploid banana cells, the protoplasts of triploid banana reformed the cell wall within 24 h and underwent sustained divisions leading to the formation of small clusters of 2–3 cells within 7 days. The latter developed directly into embryos without passing through an apparent callus phase. 10% of such embryos gave rise to plantlets when subcultured in 2.2 M 6-benzylaminopurine and 2 M 4 amino-3,5,6-trichloropicolinic acid for 1 week, before transfer to MS medium containing 10 M 6-benzylaminopurine. The rest of the embryos underwent intensive direct secondary embryogenesis which could lead to the formation of plantlets with a frequency of up to 50% upon further transfer to hormone-free medium.Abbreviations BAP 6-benzylaminopurine - MS Murashige and Skoog (1962) medium - 2,4-D dichlorophenoxyacetic acid - UV ultraviolet light - FDA fluorescein diacetate - MES 2-(N-morpholino)ethanesulfonic acid - Picloram 4 amino-3,5,6-trichloropicolinic acid