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PubMed2004

Gene content and density in banana ( Musa acuminata) as revealed by genomic sequencing of BAC clones.

The complete sequence of Musa acuminata bacterial artificial chromosome (BAC) clones is presented and, consequently, the first analysis of the banana genome organization. One clone (MuH9) is 82,723 bp long with an overall G+C content of 38.2%. Twelve putative protein-coding sequences were identified, representing a gene density of one per 6.9 kb, which is slightly less than that previously reported for Arabidopsis but similar to rice. One coding sequence was identified as a partial M. acuminata malate synthase, while the remaining sequences showed a similarity to predicted or hypothetical proteins identified in genome sequence data. A second BAC clone (MuG9) is 73,268 bp long with an overall G+C content of 38.5%. Only seven putative coding regions were discovered, representing a gene density of only one gene per 10.5 kb, which is strikingly lower than that of the first BAC. One coding sequence showed significant homology to the soybean ribonucleotide reductase (large subunit). A transition point between coding regions and repeated sequences was found at approximately 45 kb, separating the coding upstream BAC end from its downstream end that mainly contained transposon-like sequences and regions similar to known repetitive sequences of M. acuminata. This gene organization resembles Gramineae genome sequences, where genes are clustered in gene-rich regions separated by gene-poor DNA containing abundant transposons.

Base Composition↗
PubMed2005

Construction and characterization of a plant transformation-competent BIBAC library of the black Sigatoka-resistant banana Musa acuminata cv. Tuu Gia (AA).

A plant transformation-competent binary bacterial artificial chromosome (BIBAC) library was constructed from Musa acuminata cv. Tuu Gia (AA), a black Sigatoka-resistant diploid banana. After digestion of high-molecular-weight banana DNA by HindIII, several methods of DNA size selection were tested, followed by ligation, using a vector/insert molar ratio of 4:1. The library consists of 30,700 clones stored in 80 384-well microtiter plates. The mean insert size was estimated to be 100 kb, and the frequency of inserts with internal NotI sites was 61%. The majority of insert sizes fell into the range of 100+/-20 kb, making them suitable for Agrobacterium-mediated transformation. Only 1% and 0.9% of the clones contain chloroplast and mitochondrial DNA, respectively. This is the first BIBAC library for banana, estimated to represent five times its haploid genome (600 Mbp). It was demonstrated by hybridization that the library contains typical members of resistance gene and defense gene families that can be used for transformation of disease susceptible banana cultivars for banana genetic improvement.

Chromosomes, Artificial, Bacterial↗
PubMed2005

SuperSAGE combined with PCR walking allows global gene expression profiling of banana (Musa acuminata), a non-model organism.

Super-serial analysis of gene expression (SuperSAGE) was used to characterize, for the first time, the global gene expression pattern in banana (Musa acuminata). A total of 10,196 tags were generated from leaf tissue, representing 5,292 expressed genes. Forty-nine tags of the top 100 most abundantly expressed transcripts were annotated by homology to cDNA or EST sequences. Typically for leaf tissue, analysis of the transcript profiles showed that the majority of the abundant transcripts are involved in energy production, mainly photosynthesis. However, the most abundant tag was derived from a type 3 metallothionein transcript, which accounted for nearly 3% of total transcripts analysed. Furthermore, the 26-bp long SuperSAGE tags were applied in 3'-rapid amplification of cDNA ends (3'RACE) for the identification of unknown tags. In combination with thermal asymmetric interlaced PCR (TAIL-PCR), this allowed the recovery of a full gene sequence of a novel NADPH:protochlorophyllide oxidoreductase, the key enzyme in chlorophyll biosynthesis. SuperSAGE in conjunction with 3'RACE and TAIL-PCR will be a powerful tool for transcriptomics of non-model, but otherwise important organisms.

Base Sequence↗
PubMed2002

Ultrastructural changes associated with cryopreservation of banana ( Musa spp.) highly proliferating meristems.

Cryopreservation has been shown to improve the frequency of virus elimination - specifically cucumber mosaic virus and banana streak virus - from banana ( Musa spp.) plants. To understand the mode of action of cryopreservation for the eradication of viral particles, we examined the ultrastructure of meristem tips at each step of the cryopreservation process. Excised meristematic clumps produced from infected banana plants belonging to cv. Williams (AAA, Cavendish subgroup) were cryopreserved through vitrification using the PVS-2 solution. We demonstrated that the cryopreservation method used only allowed survival of small areas of cells in the meristematic dome and at the base of the primordia. Cellular and subcellular changes occurring during the cryopreservation process are discussed.

Cryopreservation↗
PubMed2002

Production of haploids from anther culture of banana [Musa balbisiana (BB)].

We report here, for the first time, the production of haploid plants of banana Musa balbisiana (BB). Callus was induced from anthers in which the majority of the microspores were at the uninucleate stage. The frequency of callus induction was 77%. Callus proliferation usually preceded embryo formation. About 8% of the anthers developed androgenic embryos. Of the 147 plantlets obtained, 41 were haploids (n=x=11). The frequency of haploid production depended on genotypes used: 18 haploid plants were produced from genotype Pisang klutuk, 12 from Pisang batu, seven from Pisang klutuk wulung and four from Tani. The frequency of regeneration was 1.1%, which was based on the total number of anthers cultured. Diploid plants (2n=2x=22) were also observed in the regenerated plants. The haploid banana plants that were developed will be important material for the improvement of banana through breeding programmes.

Culture Techniques↗
PubMed2005

Characterisation of Banana streak Mysore virus and evidence that its DNA is integrated in the B genome of cultivated Musa.

We have sequenced the complete genome of an isolate of Banana streak virus from banana cv. 'Mysore' and show that it is sufficiently different from a previously characterised isolate from cv. 'Obino l'Ewai' to warrant recognition as a distinct species, for which the name Banana streak Mysore virus (BSMysV) is proposed. The structure of the BSMysV genome was typical of badnaviruses in general, although ORF I had a non-conventional start codon. Evidence that at least part of the BSMysV genome is integrated in the B genome of cultivated Musa is presented and transmissibility by the mealybug Planococcus citri also demonstrated.

Badnavirus↗
PubMed2001

Evidence that the proliferation stage of micropropagation procedure is determinant in the expression of banana streak virus integrated into the genome of the FHIA 21 hybrid (Musa AAAB).

Banana streak virus (BSV) is causing increasing concern in almost every producing area of banana and plantain (Musa spp.) worldwide. This situation appeared partially linked to some breeding lines and micropropagated hybrids. A complete BSV sequence integrated into the genome of a triploid plantain has been recently characterised and it has been hypothesised that it could give rise to infectious virus via recombination. In this study, we evaluated the effect of a routine micropropagation procedure on the expression of BSV in the FHIA 21 tetraploid hybrid. The widespread presence of integrated sequences and the absence of episomal BSV in thirty FHIA 21 "mother plants" selected for micropropagation were first confirmed by specific PCR and IC-PCR tests. The proliferation stage of the procedure, characterised by an intensive production of neoformed buds, appeared determinant in BSV expression whereas the rooting and acclimatisation stages had little or no effect. The duration in culture and the way of subdividing the clumps of proliferation influenced greatly the percentage of episomal BSV infections, reaching 58% of infected micropropagated lines after six in vitro subcultures. These data suggest that the expression of episomal BSV observed during the in vitro procedure is correlated with the presence of an integrated form.

Badnavirus↗
PubMed2005

Microbiological and physicochemical factors affecting Aspergillus section Flavi incidence in Cavendish banana (Musa cavendishii) chips production in Southern Philippines.

Microbiological and physicochemical factors affecting the incidence of Aspergillus section Flavi in dried Cavendish banana (Musa cavendishii) chips production in Southern Philippines were examined. The average counts of Aspergillus section Flavi (AFC) in fresh and dried Cavendish bananas from 10 production batches of the Philippine Agro-Industrial Development Cooperative in Davao del Norte, Southern Philippines were 1.2 x 10(2) and 1.6 x 10(2) cfu/g, respectively. Isolates from both samples were identified to be Aspergillus flavus based on spore type and conidial structure of isolates. An increasing trend in the AFC of Cavendish bananas was observed during dried banana chips processing. Variability in the AFC between production batches was attributed to differences in aerobic and fungal populations and physicochemical characteristics of the fruits, peel damage of the raw materials, concentration of AFC in the air and food-contact surfaces of the production area, and temperature and relative humidity (RH) conditions of the environment during production and storage. Physicochemical characteristics of Cavendish bananas from the receipt of raw materials up to the first day of drying were within the reported range of values allowing growth and toxin production by aflatoxigenic fungi. Air-borne AFC varied depending on the section of the production area examined. The close proximity of the waste disposal area from the production operation to the preparation, drying and storage areas suggests that cross-contamination, probably air-borne or insect-borne was a likely occurrence. The hands of workers were also identified as AFC sources. Results of this study highlight the need for the development of strategies to control aflatoxigenic fungi and aflatoxin contamination in Philippine dried Cavendish bananas.

Air Microbiology↗
PubMed2004

Effect of phytohormones on pectate lyase activity in ripening Musa acuminata.

A differential activity peak of pectate lyase (PEL) was observed during ripening of banana fruits (Musa acuminata Harichhal) receiving different hormone treatments. Exposure of fruits to 25 ppm ethylene for 24 h, as well as dipping of M. acuminata fruits in 1 mM 2,4-dichlorophenoxy acetic acid (2,4-D) for 4 h, hastened fruit ripening. Both PEL activity peak and climacteric peak were observed on the 4th and 10th days of treatment with ethylene and 2,4-D, respectively, compared to the 16th day in control fruits. Gibberellic acid (GA) treatment retarded fruit ripening and both PEL activity and climacteric peaks were observed on the 19th day. Treatment of fruits with ethylene or 2,4-D also advanced the appearance of a polygalacturonase (PG) peak and GA delayed its appearance, but the activity peaks always appeared in post-climacteric fruits, in contrast to PEL activity peaks coinciding with the respiratory peaks.

2,4-Dichlorophenoxyacetic Acid↗
PubMed2006

Extraction and partial characterization of polyphenol oxidase from banana (Musa acuminata Grande naine) roots.

Polyphenol oxidase activity (PPO, EC 1.14.18.1, monophenol monooxygenase, and EC 1.10.3.2, o-diphenoloxidase) has been extensively studied in banana fruit for its role in enzymatic browning. Rapid discolouration of leaf, stem and root tissue after injury and strong pigmentation of tissue extracts indicate that PPO and phenolic compounds are ubiquitous in vegetative tissue of banana as well. They hamper biochemical and molecular studies in banana, as cumbersome adaptations of extraction protocols are required. On the other hand, PPO and phenolic compounds could be an important part of the plant's defence system against pests and diseases, including root parasitic nematodes. To facilitate future studies in this area, extraction and assay conditions for PPO from roots of banana (Musa acuminata AAA, Grande naine) were optimized. Highest enzyme activities were obtained in a 0.2 M phosphate buffer at pH 7.0 with 5% insoluble polyvinylpyrrolidone and 0.25% Triton X-100. The lowest K(m) values were obtained for dopamine and D-catechin. Monophenolase activity was shown with p-cresol. Banana root PPO was strongly inhibited by dithiothreitol and sodium metabisulfite. In root sections, oxidation of dopamine strongly co-localized with aerenchyma in the cortex. The experiments revealed indications for the involvement of root PPO and dopamine in resistance of banana against the parasitic nematode Radopholus similis.

Catechin↗
PubMed2003

Soluble and wall-bound phenolics and phenolic polymers in Musa acuminata roots exposed to elicitors from Fusarium oxysporum f.sp. cubense.

The accumulation of soluble and wall-bound phenolics and phenolic polymers in Musa acuminata roots exposed to cell wall-derived elicitor from the pathogen, Fusarium oxysporum, f.sp. cubense, race four, was investigated. The root tissue from the banana cultivar "Goldfinger" was found to respond strongly and rapidly towards the elicitor through the increased synthesis of phenolic compounds. Following elicitation, the conjugated and non-conjugated phenolic metabolites in the induced root tissue were extracted and quantified. Induced phenolic synthesis was rapid and reached near maximum values after 16 h. High-performance liquid chromatography revealed both compositional and quantitative differences between induced phenolics (p-coumaric, ferulic, and sinapic acids) and those constitutively present (p-coumaric- and ferulic acid). In addition, vanillic acid was found in the ester-bound fraction and protocatechuic acid in the cell-wall bound fraction of elicited tissue. The deposition and accumulation kinetics of polymerized phenolic monomers as lignin and lignin-like polymers was quantified over a time period of 0-36 h and found to reach maximum values after 24 h. Ionization difference UV spectra of lignin indicated compositional differences in the newly synthesized lignin fraction and correlated with increased concentrations of ferulic acid and sinapic acids esters. The results show that the increased flux through the phenylpropanoid pathway resulted in the synthesis of cinnamic acid and benzoic acid derivatives that were esterified and incorporated into the cell wall fraction as part of the anti-microbial defenses activated in the root tissue.

Biopolymers↗
PubMed2002

Characterization of resistant starch type III from banana (Musa acuminata).

Banana starch (Musa acuminata var. Nandigobe) was evaluated for its use in generating resistant starch (RS) type III. Structural, physicochemical, and biological properties of these products were analyzed. The investigated process includes debranching of the native starch and retrogradation under different storage temperatures and starch concentrations. After enzymatic debranching, a high amount of low-molecular-weight polymers with a degree of polymerization between 10 and 35 glucose units beside a higher molecular weight fraction were found. The resulting products comprised RS contents of about 50%. After heat-moisture treatment, the RS yield increased up to 84%. Peak temperatures of about 145 degrees C found in DSC measurements pointed to a high thermal stability of the RS products. In vitro fermentations of the RS products, carried out with intestinal microflora of healthy humans, resulted in a molar ratio of acetate:propionate:butyrate of about 49:17:34. The established method allowed the production of a high-quality RS with prebiotic properties for health preventing applications.

Amylose↗
PubMed2002

Constituents of Musa x paradisiaca cultivar with the potential to induce the phase II enzyme, quinone reductase.

A new bicyclic diarylheptanoid, rel-(3S,4aR,10bR)-8-hydroxy-3-(4-hydroxyphenyl)-9-methoxy-4a,5,6,10b-tetrahydro-3H-naphtho[2,1-b]pyran (1), as well as four known compounds, 1,2-dihydro-1,2,3-trihydroxy-9-(4-methoxyphenyl)phenalene (2), hydroxyanigorufone (3), 2-(4-hydroxyphenyl)naphthalic anhydride (4), and 1,7-bis(4-hydroxyphenyl)hepta-4(E),6(E)-dien-3-one (5), were isolated from an ethyl acetate-soluble fraction of the methanol extract of the fruits of Musa x paradisiaca cultivar, using a bioassay based on the induction of quinone reductase (QR) in cultured Hepa1c1c7 mouse hepatoma cells to monitor chromatographic fractionation. The structure and relative stereochemistry of compound 1 were elucidated unambiguously by one- and two-dimensional NMR experiments ((1)H NMR, (13)C NMR, DEPT, COSY, HMQC, HMBC, and NOESY) and single-crystal X-ray diffraction analysis. Isolates 1-5 were evaluated for their potential cancer chemopreventive properties utilizing an in vitro assay to determine quinone reductase induction and a mouse mammary organ culture assay.

Animals↗
PubMed2006

Chemical composition of abaca (Musa textilis) leaf fibers used for manufacturing of high quality paper pulps.

The chemical composition of leaf fibers of abaca (Musa textilis), which are commonly used for high-quality paper pulp production, was thoroughly studied. The results revealed that the lignin content was 13.2% of the total fiber. The analysis of abaca fibers by pyrolysis coupled to gas chromatography-mass spectrometry (Py-GC/MS) released predominantly compounds arising from lignin and p-hydroxycinnamic acids, with high amounts of 4-vinylphenol. The latter compound was demonstrated to arise from p-coumaric acid by pyrolysis of abaca fibers in the presence of tetramethylammonium hydroxide, which released high amounts of p-coumaric acid (as the methyl derivative). Products from p-hydroxyphenyl (H), guaiacyl (G), and syringyl (S) propanoid units, with a predominance of the latter (H:G:S molar ratio of 1.5:1:4.9), were also released after Py-GC/MS of abaca fibers. Sinapyl and coniferyl acetates, which are thought to be lignin monomer precursors, were also found in abaca. The extractives content of the abaca fiber (0.4%) was low, and the most predominant compounds were free sterols (24% of total extract) and fatty acids (24% of total extract). Additionally, significant amounts of steroid ketones (10%), triglycerides (6%), omega-hydroxyfatty acids (6%), monoglycerides (4%), fatty alcohols (4%), and a series of p-hydroxycinnamyl (p-coumaric and ferulic acids) esterified with long chain alcohols and omega-hydroxyfatty acids were also found, together with minor amounts of steroid hydrocarbons, diglycerides, alpha-hydroxyfatty acids, sterol esters, and sterol glycosides.

Gas Chromatography-Mass Spectrometry↗
PubMed2006

Phenylphenalenone type compounds from the leaf fibers of abaca (Musa textilis).

A series of phenylphenalenone type compounds, known to play a role as phytoalexins in plants of the Musaceae family, have been identified for the first time in the leaf fibers of abaca (Musa textilis). Among the phenylphenalenone type compounds identified, the structure of a novel compound, (1R)-2,3-dihydro-4,9-dihydroxy-8-methoxy-1-phenylphenalene, has also been described in abaca fibers. Its structure was elucidated by analysis of one- and two-dimensional NMR (correlation spectroscopy, heteronuclear single quantum correlation, and heteronuclear multiple bond correlation) spectroscopic data.

Gas Chromatography-Mass Spectrometry↗
PubMed2002

The cloning of Ty1-copia-like retrotransposons from 10 varieties of banana (Musa Sp.).

Ty1-copia-like retrotransposons have been identified and investigated in several plant species. Here, the internal region of the reverse transcriptase (RT) gene of Ty1-copia-like retrotransposons was amplified by PCR from total genomic DNA of 10 varieties of banana. Two to four clones from each variety were sequenced. Extreme heterogeneity in the sequences of Ty1-copia-like retrotransposons from all the varieties was revealed following sequence analysis of the reverse transcriptase (RT) fragments. The size of the individual RT gene fragments varied between 213 and 309 bp. Southern blots of genomic DNA digested from Musa acuminata and other banana varieties probed with W8 clone from M. acuminata and A4 clone from Pisang Abu Nipah showed similar strong, multiple restriction fragments together with other faint hybridization band patterns with variable intensities indicating the presence of many copies of the Ty1-copia-like retrotransposons in the genomes. There was no correlation between retroelement sequence and the banana species (with A or B genomes) from which it arose, suggesting that the probes are not useful for tracking genomes through breeding populations.

Base Sequence↗
PubMed2005

Unusual sugar specificity of banana lectin from Musa paradisiaca and its probable evolutionary origin. Crystallographic and modelling studies.

The crystal structure of a complex of methyl-alpha-D-mannoside with banana lectin from Musa paradisiaca reveals two primary binding sites in the lectin, unlike in other lectins with beta-prism I fold which essentially consists of three Greek key motifs. It has been suggested that the fold evolved through successive gene duplication and fusion of an ancestral Greek key motif. In other lectins, all from dicots, the primary binding site exists on one of the three motifs in the three-fold symmetric molecule. Banana is a monocot, and the three motifs have not diverged enough to obliterate sequence similarity among them. Two Greek key motifs in it carry one primary binding site each. A common secondary binding site exists on the third Greek key. Modelling shows that both the primary sites can support 1-2, 1-3, and 1-6 linked mannosides with the second residue interacting in each case primarily with the secondary binding site. Modelling also readily leads to a bound branched mannopentose with the nonreducing ends of the two branches anchored at the two primary binding sites, providing a structural explanation for the lectin's specificity for branched alpha-mannans. A comparison of the dimeric banana lectin with other beta-prism I fold lectins, provides interesting insights into the variability in their quaternary structure.

Amino Acid Motifs↗