Molecular phylogeny of banana cultivars from Thailand based on HAT-RAPD markers

Musa acuminata Colla (AA genomes) and Musa balbisiana Colla (BB genomes) are the wild progenitors of the cultivated banana, they are highly variable in Thailand. The genetic system is relatively unknown and complicated due to interspecific hybridization, heterozygosity and polyploidy, which are common in most clones. These factors make identification of closely related banana cultivars difficult, especially when sterile. The high annealing temperature-random amplified polymorphic DNA (RAPD) technique was used to estimate the genetic relationship between 22 selected banana cultivars, utilizing 14 random primers. Phylogenetic relationship was determined by unweighted pair group method with arithmetical averages cluster analysis. The dendrogram constructed from the similarity data showed that all the 22 cultivars analysed were closely related with a narrow genetic base. There were sufficient RAPD polymorphisms that were collectively useful in distinguishing the cultivars. The dendrogram grouped all the AA, BB, AAA, AAB and ABB genomes into a major cluster. Several subgroups are recognized within the major clade. As expected, Ensete glauca Roxb. (Musaceae) and Strelitzia reginae Banks (Strelitziaceae) were clearly differentiated from the analysed edible bananas. Our study showed that RAPD markers are sufficiently abundant to classify and readily dissect genetic differences between the closely related Musa germplasm and provide a basis for the selection of parents for improvement of this germplasm.     

Sampling strategies and variability in fruit pulp micronutrient contents of west and central african bananas and plantains (Musa species)

The variability in fruit micronutrient contents in a selection of Central and West African Musa varieties cultivated under standardized field conditions was studied. Analysis of the within-fruit, within-hand, and within-plant as well as the between-plant variations demonstrated that both provitamin A carotenoids (pVACs) and mineral micronutrient (Fe, Zn) contents vary significantly across all sample groups. The variations in pVACs contents appear to be at least partly related to differences in the developmental status of the fruit, but the observed trends were genotype-specific. The mean pVACs concentrations per genotype indicated that there is substantial genetic variation in the fruit pVACs contents between Musa cultivars, with orange-fleshed plantain varieties (AAB) having generally higher fruit pVACs contents than dessert bananas (AAA). It was not possible to identify consistent trends between the sampling position and fruit Fe/Zn contents. Once the within-bunch micronutrient variability has been accounted for, the mean variations in fruit micronutrient contents between individual plants of a variety generally fell to within acceptable limits. Results are discussed within the framework of standardizing sampling and developing strategies to screen for the nutritional values of new and existing Musa varieties.     

Effect of banana crop mixtures on the plant-feeding nematode community

Varietal mixture is a cultural technique in which the genetic and functional diversities of varieties are used to manage pests and diseases. This strategy is commonly used on grass crops such as rice, barley, maize, and wheat to mitigate some windborne and soilborne pathogens. The effects of varietal mixtures on the number and community structure of pests, including plant-feeding nematodes (PFNs), however, have rarely been studied. In experiments conducted in Martinique, we evaluated the effect of varietal mixtures of bananas on PFN communities. A growth chamber experiment was used to measure the susceptibility of three banana cultivars dessert banana cv. 902 (Musa AAA, Cavendish subgroup); a new synthetic hybrid cv. FB924 (Musa AAA); and a plantain cv. Creole blanche (Musa AAB, French Horn) to the two major PFNs. The multiplication rates of Radopholus similis and Pratylenchus coffeae were substantially different on the three varieties; for example, the multiplication rate was up to 10 times greater on plantain cv. Creole blanche than on hybrid cv. FB924. In a field experiment, we planted the three varieties in pairs that included all six possible combinations. Banana varietal mixtures significantly affected both PFN densities and community composition. Differences in community composition among the pairs involved a shifting equilibrium among nematode species and an interspecific competition for food resources. The relative abundance of the spiral nematode Helicotylenchus multicinctus increased while that of the burrowing nematode R. similis, which is the most damaging species on bananas, decreased. The use of a varietal mixture in which one variety supports a low PFN multiplication rate appears to have practical relevance, especially in systems based on very susceptible cultivars such as plantains. The use of varietal mixtures should not create management problems, especially for plantations that produce bananas for local markets.     

Ecology and morphological traits of an ancient <Emphasis Type="Italic">Musa acuminata</Emphasis> cultivar from a mountain oasis of Oman

Recent reports have shown a surprising diversity of agricultural crops in Omani oases which was attributed to the country’s traditional role at the crossroads of cultures and trade between the Middle East and Asia. Recent surveys have indicated a relatively small diversity of banana (Musa spp.) germplasm which was thought to reflect the prevailing hyperarid conditions of Oman where this drought-sensitive species can only be cultivated in well-watered oases in the North or in Dhofar, the monsoon-dominated south eastern tip of the Sultanate. Surveys near Umq Bi’r, a half-abandoned oasis in the hardly accessible spring area of Wadi Tiwi, famous with Arabic sailors for its abundant fresh water resources, led to the discovery of a so far undescribed triploid Musa acuminata cultivar surviving in a limestone rock niche. Its morphological traits are different from any of the currently grown banana cultivars. Since acuminata bananas are quite sensitive to drought spells, characteristic for the Arabian Peninsula, the occurrence of this specimen provides further evidence for Oman’s role as a refuge of relict crops imported from a more humid region such as coastal East Africa and nearby islands, or Indonesia.     

Descriptive and multivariate analyses of morphotaxonomic and yield-related traits in inflorescence dichotomous cultivars of Musa species (AAB genome)

Genetic Resources and Crop Evolution - Genetic diversity in Musa species (AAB genome) has been collected and conserved in several germplasm banks in different parts of the world. However, not many...     

Plantain and banana starches: granule structural characteristics explain the differences in their starch degradation patterns

Different banana cultivars were used to investigate the influences of starch granule structure and hydrolases on degradation. The highest degrees of starch degradation were observed in dessert bananas during ripening. Scanning electron microscopy images revealed smooth granule surface in the green stage in all cultivars, except for Mysore. The small and round granules were preferentially degraded in all of the cultivars. Terra demonstrated a higher degree of crystallinity and a short amylopectin chain length distribution, resulting in high starch content in the ripe stage. Amylose content and the crystallinity index were more strongly correlated than the distribution of amylopectin branch chain lengths in banana starches. α- and β-amylase activities were found in both forms, soluble in the pulp and associated with the starch granule. Starch-phosphorylase was not found in Mysore. On the basis of the profile of α-amylase in vitro digestion and the structural characteristics, it could be concluded that the starch of plantains has an arrangement of granules more resistant to enzymes than the starch of dessert bananas.     

Genetic diversity of Musa diploid and triploid accessions from the Brazilian banana breeding program estimated by microsatellite markers

Banana (Musa spp.) is one of the most consumed fruits worldwide. Production is based mainly on triploid cultivars, and most genetic improvement programs aim to generate tetraploid hybrids obtained from the crossing of established triploid cultivars with a diploid parent genotype, improved or wild, exhibiting the trait of interest, normally resistance to biotic factors. Microsatellites were used to investigate the genetic variability and relationships between 58 Musa genotypes, including 49 diploids and nine triploid cultivars maintained at the Musa germplasm collection of the Brazilian dessert banana breeding program. Thirty-three primer pairs developed for banana were tested, and nine amplified reproducible and discrete fragments, producing a total of 115 alleles. The average number of alleles amplified per primer was 12.8, ranging from 10 to 15. The diploid genotypes presented the largest genetic variability, demonstrated by the large number of alleles detected, and the low similarity between the clones. The phenetic analysis clustered the triploid cultivars in a separated group, with the exception of the Nanica and Gros Michel cultivars, which showed high similarity with the diploid cultivar Mambee Thu. It was not possible to separate the wild diploid genotypes from the cultivated ones, indicating a common origin of these genotypes. A high proportion of duplicated alleles and/or loci was observed for diploid and triploid genotypes. The information gathered about the similarity between diploid and triploid accessions will help to define potential crosses to maximize the recovery of the typical fruit qualities required in Brazil (AAB, Pome and Silk dessert banana).     

Random amplified polymorphic DNA and genetic diversity in IndianMusa germplasm

Summary Fifty-seven accessions ofMusa including cultivated clones of 6 genomic groups (AA, AB, AAA, AAB, ABB, ABBB),M. balbisiana Colla (BB),M. acuminata Colla ssp.banksii F. Muell. (AA),M. acuminata Colla ssp.malaccensis Ridl. (AA) andM. velutina Wendl. & Drude were examined for random amplified polymorphic DNA (RAPD) genetic markers using PCR with sixty 10-mer random primers. Forty-nine of 60 tested primers gave reproducible DNA amplification patterns. The number of bands resolved per amplification was primer dependent and varied from 1 to a maximum of 24. The size range of the amplification products also differed with the selected primer sequence/genotype and ranged from 0.29 to 3.0 kb. RAPD data were used to generate Jaccard's similarity coefficients which were analyzed phenetically. Phenetic analysis separated clones into distinct groupings that were in agreement with clusterings revealed when data were subsequently analyzed by principal coordinate analysis (PCO). In both the phenetic and the PCO analyses, previously unclassified cultivars grouped with cultivars previously classified for their genomic group based on morphological keys. The implications of RAPD analysis forMusa germplasm classification, clonal identification, and management are discussed.     

Genetic diversity of wild banana (<Emphasis Type="Italic">Musa balbisiana</Emphasis> Colla) in China as revealed by AFLP markers

Wild banana Musa balbisiana Colla is one of the progenitors of cultivated bananas and plantains. It is native to Southeast Asia and the western Pacific. South China represents the northern limit of its distribution range. The genetic diversity of Musa balbisiana was assessed by the amplified fragment length polymorphism (AFLP) fingerprinting in 15 populations of China. Four primer pairs produced 199 discernible loci. High levels of genetic diversity were detected, with P = 78.5%, H _E = 0.241, and H _pop = 0.3684 at population level, and P = 100%, H _T = 0.3362 and H _sp = 0.5048 at species level. Significant genetic differentiation among populations was detected based on Hickory’s analysis (27.6%), Shannon’s diversity index (27.0%) and AMOVA (27.1%). The AFLP results are discussed and compared with data obtained by microsatellites method. The estimates of genetic diversity and differentiation between each pair of populations computed with microsatellites and AFLP markers were not significantly correlated. Conservation strategies for Musa balbisiana in China are proposed.     

Anthocyanin composition of wild bananas in Thailand

Anthocyanins were isolated from male bracts of 10 wild species of bananas (Musa spp. and Ensete spp.) distributed in Thailand. Six major anthocyanin pigments were identified by high performance liquid chromatography (HPLC), mass spectrometry (MS), and tandem mass spectrometry (MS/MS). They are delphinidin-3-rutinoside (m/z 611.2), cyanidin-3-rutinoside (m/z 595.8), petunidin-3-rutinoside (m/z 624.9), pelargonidin-3-rutinoside (m/z 579.4), peonidin-3-rutinoside (m/z 608.7), and malvidin-3-rutinoside (m/z 638.8). On the basis of the types of pigment present, the wild bananas can be divided into 5 groups. The first group comprises M. itinerans, Musa sp. one, Musa sp. two, and M. acuminata accessions, which contain almost or all anthocyanin pigments except for pelargonidin-3-rutinoside, including both nonmethylated and methylated anthocyanins. The second group, M. acuminata subsp. truncata, contains only malvidin-3-rutinoside while the third group, M. coccinea, contains cyanidin-3-rutinoside and pelargonidin-3-rutinoside. The forth group, M. acuminata yellow bract and E. glaucum do not appear to contain any anthocyanin pigment. The fifth group consists of M. balbisiana, M. velutina, M. laterita, and E. superbum which contain only nonmethylated anthocyanin, delphinidin-3-rutinoside, and cyanidin-3-rutinoside. Total anthocyanin content in the analyzed bracts ranged from 0-119.70 mg/100 g bract fresh weight. The differences in the type of anthocyanin and variation in the amounts present indicate that wild bananas show biochemical diversity, which may be useful for identifying specific groups of bananas or for clarifying the evolution of flavonoid metabolism in each banana group.     

Ploidy distinction in male and female plants of betelvine (<Emphasis Type="Italic">Piper betle</Emphasis> L.): a study by flow cytometry

Piper betle L. (betelvine) is a dioecious species which is a native of Central and South East Asia and it is cultivated in an area of about 50,000 ha in India. The basic chromosome number of this species is x?=?13. Only fragmented work has so far been reported on chromosome numbers and ploidy status. The extremely small size and high number of chromosomes, interclonal variability and very dense cytoplasmic contents make critical analysis difficult. In India, a large number of germplasm has been collected and assembled in All India Co-ordinated Research Project on Betelvine centers by sustained efforts of betelvine workers over a period of two and half decades. Hybridization work was also initiated and a few hybrids have been developed in India. But hybrid depression was noticed in most of the hybrids. Hence a study was undertaken to determine compatible ploidy level of available male and female germplasm using flow cytometry. Cytological studies conducted in a selected male cultivar revealed 2n?=?3x?=?39 and female cultivar it was 2n?=?4x?=?52 chromosomes and these cultivars were used as control samples in the flow cytometry analysis. Flow cytometric study showed that all male accessions were grouped within the same ploidy level (triploid) while all females were grouped in another ploidy group (tetraploid). The present study also gave explanation for the observed hybrid depression due to the possibility of aneuploid hybrid formation by the fusion of unbalanced gametes developed from the triploid male parents. Flow cytometry could thus be utilized for the rapid screening and earlier detection of the aneuploids in hybrid seedlings in the species. Separation of sexes by ploidy difference is also a new report in P. betle.     

Potential of landrace germplasm for genetic enhancement of white lupin in Egypt

Landraces of white lupin (Lupinus albus L.) collected in Egypt were evaluated along with locally developed cultivars and selected foreign germplasm for yield and major morphological characteristics in five different locations. These locations represent different soil types and climatic conditions in Egypt. The results showed an outstanding performance of the local cultivar checks across traditional locations for lupin cultivation, which supports the utilization of local germplasm for further improvement of locally adapted lupins in Egypt. The results further suggest that local landrace germplasm may be an important source of alleles for shortening the vegetative period, reducing plant height and stem length, as well as for improving some yield components as number of pods and seeds per plant. The genotype-by-location interaction was significant for all characteristics. Mass selection in the Egyptian germplasm collection of white lupin has the potential for enhancing yield, especially in germplasm adapted to newly reclaimed desert locations.     

Utility of Metabolomics toward Assessing the Metabolic Basis of Quality Traits in Apple Fruit with an Emphasis on Antioxidants

A gas chromatography-mass spectrometry approach was employed to evaluate the use of metabolite patterns to differentiate fruit from six commercially grown apple cultivars harvested in 2008. Principal component analysis (PCA) of apple fruit peel and flesh data indicated that individual cultivar replicates clustered together and were separated from all other cultivar samples. An independent metabolomics investigation with fruit harvested in 2003 confirmed the separate clustering of fruit from different cultivars. Further evidence for cultivar separation was obtained using a hierarchical clustering analysis. An evaluation of PCA component loadings revealed specific metabolite classes that contributed the most to each principal component, whereas a correlation analysis demonstrated that specific metabolites correlate directly with quality traits such as antioxidant activity, total phenolics, and total anthocyanins, which are important parameters in the selection of breeding germplasm. These data sets lay the foundation for elucidating the metabolic basis of commercially important fruit quality traits.     

Characterization of core collection of lentil germplasm for phenology, morphology, seed and straw yields

Increasing and maintaining crop residues in predominantly cereal-based rotations of the US Pacific Northwest is critical to controlling soil erosion. The core collection of lentil (Lens culinaris Medik.) germplasm comprising 287 accessions was evaluated for variation in phenological, morphological and growth parameters including seed yields and residue amounts over a two-year period under conventional tillage and no-till conditions. The objectives of this study were (i) assess lentil genetic variation in germplasm for variation in biomass production and seed yield, (ii) assess the relationship of phenological and morphological traits with biomass and seed yield and (iii) identify high biomass producing germplasm for use as parents in the breeding program. Days to flowering and days to maturity ranged from 31 to 78 and from 71 to 106 days, respectively. Time to flowering in terms of cumulative heat units was a more efficient measurement than days to flowering. Plant height and plant canopy width had a significant association with total biomass, seed yield and residue amounts. Total biomass ranged from 788–6389 kg ha^–1 under conventional tillage, while the range under no-till conditions was 1045–6195 kg ha^–1. Most of the lines with higher biomass also produced the highest seed yields and residue amounts. Overall, only one accession produced more residue than `Laird'. In the more favorable environment of 1997, six accessions exceeded the control cultivars, `Laird' and `Indianhead', for residue amounts, and seven and twenty-four accessions exceeded control cultivars, `Pardina' and `Brewer', for seed yield. Results indicated that plant height, canopy width at maturity and seed yield explained most of the variation in biomass and residue production. Large seeded germplasm consistently had a longer reproductive growth period than small seeded accessions and had 17%, 7% and 21% more biomass, seed yield and residue, respectively. Our data indicated significant variation in lentil germplasm for biomass, seed yield and residue amounts to warrant their use in the breeding program.     

Organelle DNA sequence data provide new insights into the maternal and paternal lineages of Musa species germplasms

Genetic Resources and Crop Evolution - Single-copy organelle DNA loci are widely used to infer plants’ phylogenetic relationships. In bananas (Musa spp.), the maternal transmission of...