Banana Clones Research Articles

Variability in storage potential of banana shoot cultures under medium term storage conditions

Shoot cultures of 401 banana clones were conserved under slow growth conditions (16±1°C, 25μmol m−2 s−1). Storage duration-defined as 60% survival time of 20 shoot cultures of a clone-averaged 334 days. However, large differences occurred among the different genomic (sub)groups and even within the same (sub)group. East-African highland bananas and non-plantain AAB bananas can be stored for significantly longer periods. Shoot tip cultures of another 41 banana clones conserved at higher ambient temperature (22±3°C) needed to be subcultured sooner (every 220 days on average).

Selection parameters for resistance to Fusarium oxysporum f. sp. cubense race 1 and race 4 on diploid banana (Musa acuminata Colla)

Shoot tip cultures from banana clones susceptible and resistant to Fusarium oxysporum f. sp. cubense (FOC) race 1 and race 4 were grown in vitro in the presence of different concentrations of fusaric acid and fungal crude filtrates or inoculated with a conidial suspension of FOC to assess correlation between in vivo and in vitro behaviour. Explants were susceptible to both filtrate and fusaric acid irrespective to their known field resistance/susceptibility response. No clear linkage between in vivo and in vitro behaviour was observed and our results suggest that the use of crude filtrate or non-host specific toxin (fusaric acid) in a screening programme for selecting a novel resistant genotype of Musa to FOC is not feasible. When peroxidase activity was used as a parameter to discriminate between sesceptibility and tolerance, results were in good agreement with field response of host plant to pathogens. Early enzymatic activity increased in the incompatible host-pathogen interaction but not in the compatible interaction.

RANDOM AMPLIFIED POLYMORPHIC DNA (RAPDs) DETECTS PATTERNS OF GENETIC DIVERSITY IN DIPLOID MUSA ACUMINATA COLLA

Patterns of diversity among thirty diploid clones of banana (Musa acuminata Colla.), collected in Papua New Guinea and the surrounding islands between 1987 and 1989, were examined genetically using the polymerase chain reaction (PCR) and random primers, to detect random amplified polymorphic DNA (RAPDs). PCR products were visualized on ethidium bromide stained agarose gels. Twenty of 60 random primers examined detected RAPDS in CTAB-extracted genomic DNA. Banding patterns ranged from very simple (1 or 2 bands/gel) to very complex (more than 20 bands/gel). All 30 Musa clones were distinguishable from each other based on their unique RAPD banding pattern. Principal component analysis (PCA) revealed several clusters of closely related clones within the materials examined. However, these clusterings were not correlated with either the geographic origin or the morphological characteristics of the clones. A role of the use of RAPDs in germplasm characterization is discussed.

Variation of ribosomal gene spacer length among wild and cultivated banana.

The diversity of rDNA spacer length (IGS) of 107 wild and cultivated clones of banana belonging to different genetic groups, was studied using a sulphonated wheat rDNA probe. The length of the rDNA unit was between 10 and 12.6 kb and was highly variable. Fifteen different types of IGS could be observed. IGS diversity within the acuminata complex was greater among the diploid cultivars than among the triploid cultivars. Variation was also found among BB genotypes and confirms the diversity of this species. As opposed to previous studies, based on enzymatic or poly-phenolic markers, there was no obvious relation between the rDNA structure and the classification into genetic groups. More particularly, the IGS variations did not differentiate between the A and B genomes. This analysis, however, indicates a relationship between the geographical origin and the IGS structure of Thai and Indonesian clones.

In vitro action of ethylmethanesulphonate on banana shoot tips

Shoot tips excised from two banana ( Musa acuminata) clones (SH-3362, a diploid AA, and cultivar ‘Grand Nain’ mutant (GN-60Gy/A), a triploid AAA) were treated with various concentrations of the mutagen ethylmethanesulphonate (EMS). The number of newly initiated adventitious buds decreased with increased concentrations of EMS. Presence of dimethylsulphoxide (DMSO) in combination with EMS affected the growth and development of the shoot tips. Uptake of the labelled mutagen ( 14C EMS) was greatly influenced by time of incubation and presence of DMSO as a carrier agent. Microautoradiography of histological sections of shoot tips confirmed the accumulation of the labelled mutagen in the shoot apical meristem, leaf primordia and more extensively in the corm, from which new adventitious buds are initiated.

Adventitious shoot production from calloid cultures of banana

Isolated tips (approx. 2 mm long) from aseptic, multiplying shoot cultures of the triploid dessert banana clone 'Highgate' were tested for their morphogenetic responsiveness to hormone treatments on semisolid media. Medium containing Murashige and Skoog (1962) salts, p-chlorophenoxyacetic acid, and kinetin produced a compact calloid mass. Protuberances disclosed by SEM as rounded, button-shaped, and pointed outgrowths resembling fasciated shoots were formed in profusion. Sections showed many meristematic regions, some associated with distinct leaf primordia. Formation and growth of successive leaves yielded small, elongated, adventitious shoots with constricted bases. Transferral to a basal MS medium with 1 mg/l 1-naphthaleneacetic acid (NAA) led to the formation of rooted plantlets.

Isozymes as genetic markers in bananas and plantains

Twenty-four clones of banana and plantain representing various levels of ploidy and diploid M. balbisiana, were analysed for enzyme variants of malate dehydrogenase, phosphoglucomutase, glutamate oxaloacetate transaminase, shikimate dehydrogenase and peroxidase. Polymorphism was detected in all 5 enzyme systems. In addition, the four principal Cavendish clones, Robusta, Giant Cavendish, Dwarf Cavendish and Pisang masak hijau were found to be monomorphic for isozymes of 10 additional enzymes. Isozymes of glutamate oxaloacetate transminase were the most useful for discriminating among clones of a particular genomic group.

Organ Formation in Musa Tissue Cultures

Summary Spherical callus masses which resembled globular embryos developed on the surface of and within leaf base explants of various cultivated banana clones when they were cultured without illumination for 30 to 60 days on a basal medium containing Murashige and Skoog (MS) salts, i- inositol (100 mg·1- 1 ), thiamine·HCl (0.4 mg·1- 1 ), sucrose (30 g·1- 1 ), supplemented with 0.1% (w/v) activated charcoal, various concentrations of dicamba and solidified with 0.3% (w/ v) agar. Inclusion of kinetin or BA in addition to dicamba during culture initiation suppressed the formation of these callus masses. Transfer of leaf base explants to hormone-free basal medium or to MS with a lower concentration of dicamba resulted in rapid enlargement and elongation of the globular masses. Although root elongation occurred, shoot formation from these elongated structures was never observed.

Rapid Multiplication of Bananas and Plantains by In Vitro Shoot Tip Culture

Abstract Rapidly multiplying cultures of dessert banana clones (‘Philippine Lacatan’ and ‘Grande Naine’) and plantain clones (‘Saba’ and ‘Pelipita’) were established from isolated shoot tips on a modified Murashige and Skoog medium supplemented with 5.0 mg/liter 6-benzylamino purine (BA). The growth rates of these cultures, expressed as increase in fresh weight over a 4-week period, were assessed. Rooted plantlets were produced using the auxins naphthaleneacetic acid (NAA), indole-3-butyric acid (IBA), or indole-3-acetic acid (IAA) at 1 mg/liter with low levels of activated charcoal (0.025% w/v).

Multiplication of Musa from Excised Stem Tips

Rapidly multiplying cultures were established from excised shoot tips of two dessert banana clones ('Philippine Lacatan' and 'Grande Naine') and two plantain clones ('Pelipita' and 'Saba'). Apices cultured on semi-solid media produced single shoots while apices placed in liquid media produced shoot clusters. Individual shoots were induced to form multiple shoot clusters by longitudinally splitting the shoot through the apex. Shoot multiplication was stimulated maximally by 5 mg l-1 benzylaminopurine. Rooted plants were produced by treating shoots with auxins. Growth rates based on increase in f. wt of the four clones were compared. During a 4-week culture period 'Pelipita' showed a fivefold increase in f. wt while 'Grande Naine', 'Philippine Lacatan' and 'Saba' showed increases exceeding tenfold.

Possible sources of resistance to black sigatoka in the Papua New Guinea biological foundation banana collection

Abstract Two hundred and sixtyfour banana clones, all but fourteen indigenous to Papua New Guinea, were assessed for their susceptibility to black Sigatoka (Mycosphaerella fijiensis Morelet var. difformis Mulder & Stover). Assessments were made during both wet and dry seasons. Thirtyfive clones were identified as having low levels of susceptibility to black Sigatoka. Fifteen of these are AA genome and are potentially useful in a breeding programme.

Post‐harvest physiology of tetraploid banana fruit: response to storage and ripening

SUMMARYAspects of the post‐harvest physiology relating to storage and ripening of the fruit of tetraploid banana clones resistant to Sigatoka disease, have been compared with fruit of Valery, an important commercial triploid cultivar. Significant differences in susceptibility to low temperature injury, duration of the preclimacteric period, the texture of pulp and peel and ethylene evolution have been found between tetraploid and Valery fruit and also between tetraploid fruit of different clones.Fruit of Valery and one tetraploid clone developed serious chilling injury during storage at 12 °C whereas that of five other tetraploid clones showed only slight damage. The preclimacteric period for fruit of two tetraploid clones was 30–45% less than for Valery fruit at an equivalent stage of physical development. Pulp firmness of preclimacteric tetraploid fruit was 20–30% less than that of Valery fruit and the differences persisted through ripening. The softening response to applied ethylene was up to 15 h earlier in fruit of tetraploid clones than of Valery but respiratory patterns, colour development and starch‐to‐sugar conversion were similar. Unlike Valery fruit, ripe tetraploid fruit did not develop senescent spotting, and shelf life was terminated by rapid deterioration of peel strength to a state of severe finger drop. Temporal and quantitative differences occurred between fruit of tetraploid clones and Valery in production of ethylene and these may relate to the observed differences in control of softening in both pulp and peel.

Freckle disease of banana in Hawaii caused by Phyllostictina musarum (Cke.) Petr

SUMMARY‘Freckle’ (‘black‐spot’ disease) of bananas is common on leaves and fruit of Dwarf Cavendish and other varieties in Hawaii, especially after rainy periods. On fruit, symptoms may appear 2–4 weeks after the bunch has opened, and become more severe as maturity is approached. The disease is usually confined to older leaves on affected plants. Freckled tissue contains numerous pycnidia of Phyllostictina musarum and disease was experimentally induced by inoculating leaves and fruit with conidia of this fungus. This appears to be the first record of successful inoculation with P. musarum.Conidia of P. musarum germinate after 3–6 h in a film of water on banana peel, appressoria being formed after 18–30 h. Penetration of the epidermis occurs 24–96 h after inoculation, and is brought about by an infection hypha which grows from the appressorium. The progressive increase in severity of freckle as fruit matures is due to repeated infection by further conidia of P. musarum, rather than to enlargement of original infections. Some banana clones, including Gros Michel, appear to be resistant to the fungusDispersal of P. musarum conidia immediately after discharge from the pycnidium is chiefly by rainwater and dew. Secondary infections contribute greatly to the total number of infections. Conidium dispersal by water often results in the development of characteristic patterns of spotting, chiefly in the form of streaks or circular areas, coinciding with the directions of movement of rainwater and dew. Large numbers of conidia of P. musarum are washed on to fruit in rainwater and dew running from diseased, overhead leaves.

Megasporogenesis and female fertility in three edible triploid bananas

The female cytology of three edible triploid banana clones (‘Mysore’, ‘Pisang awak’, ‘Bluggoe’) is described. Irregularities of meiosis and embryo-sac formation are numerous and development is often delayed in respect to ovary development or altogether arrested. Mature embryo-sacs are therefore rare. Comparison of seed fertilities of the three clones with their cytology suggests that embryo-sac formation is limiting to fertility in at least two of them. In ‘Gros Michel’, by contrast, embryo sac frequency far exceeds fertility, thus giving some encouragement to the banana breeder’s hope of manipulating the seed yield of this clone. The observations, for technical and statistical reasons, give little information about the origin of polyploid progeny; indirect inference suggests that both “Rosenberg” and “Musa-type” restitutions are concerned.