Musa AAA Research Articles

Efecto de la inmersión en agua caliente sobre la secreción de látex por la corona de gajos recién conformados de frutos de banano

Con el objetivo de evaluar el efecto de la temperatura del agua y el tiempo de inmersión sobre la secreción de látex por la corona de gajos recién conformados de frutos de banano, se realizaron 2 experimentos con racimos de 12 semanas de edad (floración-cosecha) del cv. Valery (Musa AAA, subgrupo Cavendish). En el experimento 1 se evaluaron 4 temperaturas del agua: 25, 35, 45 y 55°C y, 4 tiempos de inmersión: 5, 10, 15 y 20 min en conjunto con un tratamiento testigo comercial. En el experimento 2 se evaluó unicamente la temperatura del agua a 45°C y 2 tiempos de inmersión: 10 y 20 min. En este experimento se incluyó un tratamiento testigo comercial (frutos tomados de la línea de empaque de la finca) y otro tratamiento testigo conformado por frutos cuyos gajos fueron empacados inmediatamente después de la separación del racimo (testigo absoluto). En ambos experimentos la inmersión de los frutos en agua caliente se realizó inmediatamente después que las manos fueron seccionadas del racimo y conformadas en gajos. En ambos experimentos no hubo maduración prematura durante el periodo de simulación de transporte que fue de 15 días. En el experimento 1 los tratamientos expuestos a 55°C, presentaron daño severo de quemadura en la cáscara. En el experimento 2 no se afectó la firmeza (p > 0,2685), aunque hubo diferencias estadísticas en el color de la cáscara (p < 0,0145) y en los sólidos solubles (p > 0,0001). El tratamiento de inmersión de 45°C por 10 min demostró que puede ser tan efectivo en la remoción del látex de la corona de gajos recién conformados de frutos de banano como el tratamiento comercial, basado en la inmersión sucesiva de los frutos en depósitos de agua circulante y la posterior aplicación de fungicidas y cicatrizantes.

Effect of leaf pruning at flower emergence of banana plants (Musa AAA) on fruit yield and black Sigatoka (Mycosphaerella fijiensis) disease

Two experiments were conducted to evaluate the effect of banana (Musa AAA) leaf pruning intensities at flower emergence on fruit yield and black Sigatoka leaf infection. In both experiments a decreasing linear effect of leaf pruning intensities was observed on the number of functional and total leaves of the parental plant at harvest. Leaf pruning intensities did not affect bunch weight and fruit length in any experiment. As leaf pruning intensity increased there was a significant rectilinear increase in the flowering index in the first, second and third flowering ratoon crops. In the plant crop experiment black Sigatoka variables were not affected by leaf pruning. However, in the ratoon crops experiment, as leaf removal increased, black Sigatoka severity decreased at 4 and 8 weeks, and was similar at 11 weeks after flower emergence. The results support leaf pruning at flower emergence as a tool for inclusion in the integrated management of black Sigatoka severity, because there was either no reduction in bunch weight or any change in ratooning times.

Study of banana (Musa aaa Cavendish cv Nanica) trigger ripening for small scale process

The present work focuse on the impact of O2, CO2 and ethylene concentrations on ripening rate control of bananas as a contribution for the development of domestic equipments that could allow the user to drive the fruit shelf live. It represented the adjustment of metabolic activity rates in order to manage the maturity process. Ripening variables such as ethylene and CO2 concentrations and temperature were adjusted to accelerate or slow down the process, while the maturity degree was monitored through the physical and chemical parameters and sensorial analysis. Therefore, the objective of this work was to evaluate the influence of these parameters to manage the banana ripening. The optimum temperature was at 25 ºC of storage. The presence of oxygen, CO2 withdraws and ethylene injection were relevant for the ripening process. The "ready-to-eat" quality was achieved in 6 days in confined system. The use of ethylene as trigger was adequate to accelerate the ripening process with advantages in fruit color.

Nematode resistance in bananas: screening results on some new Mycosphaerella resistant banana hybrids

Banana hybrids with resistance to Yellow Sigatoka and Black Leaf Streak disease were evaluated for resistance to the burrowing nematode Radopholus similis and to the lesion nematode Pratylenchus coffeae in a growth chamber at 24–28°. Plants produced by tissue culture were acclimatised for 6 weeks prior to inoculation. Forty-five days after inoculation with nematodes, the root systems were processed and nematode numbers assessed. Two cultivars of Grande Naine (Musa AAA, Cavendish subgroup, ITC1256 and cv902) and one cultivar of Yangambi Km5 (Musa AAA, Ibota subgroup, ITC1123) were used respectively as susceptible and resistant controls. Results based on multiplication rates and root infestations showed that three of these hybrids (FB918, FB919 and FB924) were not significantly different from the resistant control Yangambi Km5 with a lower multiplication of R. similis. Similarly four of these hybrids (FB918, FB919, FB920, FB924) showed a lower multiplication of P. coffeae, not significantly different from the same resistant control. This is the first study that shows a partial resistance to both nematode species, R. similis and P. coffeae within synthetic hybrids of M. acuminata, adding an important extra value to these dessert banana hybrids formerly bred to resist to Mycosphaerella leaf spot diseases.

Altered Response to Biotic and Abiotic Stress in Tissue Culture-Induced Off-Type Plants of East African Highland Banana (Musa AAA East Africa)

Altered Response to Biotic and Abiotic Stress in Tissue Culture-Induced Off-Type Plants of East African Highland Banana (Musa AAA East Africa)

Susceptibility of banana intercrops for rhizobacteria, arbuscular mycorrhizal fungi and the burrowing nematode Radopholus similis

The susceptibility of 7 non-leguminous and 7 leguminous banana intercrops (and rotation crops) for rhizobacteria, mycorrhizal fungi and the burrowing nematode Radopholus similis was investigated and compared with the host response of banana cv. Grande Naine ( Musa AAA group). In 50% of the tested combinations, the bacteria elicited nodules but these nodules were effective in fixing nitrogen only in about 11% of the tested combinations. Of the non-leguminous intercrops tested, wormseed, sweet potato cv. Tapato and cotton showed a poor mycorrhizal compatibility, based on the frequency ( F%) and intensity ( I%) of mycorrhizal colonisation. Of the leguminous intercrops tested, soybean, Grant's rattlebox, common bean, pigeon pea and sunn hemp showed a moderate mycorrhizal compatibility. Overall, F% and I% were higher in the leguminous intercrops compared with the non-leguminous intercrops. The susceptibility for R. similis differed among the intercrops tested. In the non-leguminous intercrops, marigold, sweet potato cv. Tapato, cotton and sesame were non-hosts, sweet potato cv. Inzovu, sorghum were intermediate hosts and sorgho-sudangrass was a good host. In the leguminous intercrops, hairy indigo was a non-host, Grant's rattlebox, soybean and sunn hemp were poor hosts and cowpea, common bean and pigeon pea were intermediate hosts.

Karyotypic and 2C Nuclear DNA Size Instability in vitro Induced Off-Types of East African Highland Banana (Musa AAA East Africa)

Karyotypic and 2C Nuclear DNA Size Instability in vitro Induced Off-Types of East African Highland Banana (Musa AAA East Africa)

The effect of meta-topolins on micropropagation of ‘Williams’ banana (Musa AAA sub group Cavendish)

The effect of meta-topolins on micropropagation of ‘Williams’ banana (Musa AAA sub group Cavendish)

Inflorescence proliferation for somatic embryogenesis induction and suspension-derived plant regeneration from banana (Musa AAA, cv. ‘Dwarf Cavendish’) male flowers

Availability of explants with adequate embryogenic competence is one of the most important limitations for the development of regenerable cell suspensions in banana. To increase the number and ease of accessibility to potentially embryogenic explants, a novel methodology is described by which young male flower clusters isolated from adult plants are induced to form new flower buds and proliferate in vitro. Different concentrations of the plant growth regulator thidiazuron (TDZ) induced inflorescence proliferation, which could be maintained over time as a continuous source of young flower buds. Intensity of proliferation was evaluated during successive subcultures. At the third cycle of proliferation, the highest multiplication rate (2.89) was obtained on the medium containing 5 microM TDZ. Newly generated floral tissues were assessed for embryogenic competence, resulting in an average embryogenic frequency of 12.5%. The observed embryogenic capacity, together with the recurrent availability of immature flowers, allowed for the direct initiation of cell suspensions from bulked explant cultures. Regular observation and regeneration tests during the development of suspended cell cultures confirmed their embryogenic condition. Produced embryos successfully matured and germinated to regenerate hundreds of somatic in vitro plants.

Characterisation of pectins extracted from banana peels (Musa AAA) under different conditions using an experimental design

An experimental design was used to study the influence of pH (1.5 and 2.0), temperature (80 and 90°C) and time (1 and 4h) on extraction of pectin from banana peels (Musa AAA). Yield of extracted pectins, their composition (neutral sugars, galacturonic acid, and degree of esterification) and some macromolecular characteristics (average molecular weight, intrinsic viscosity) were determined. It was found that extraction pH was the most important parameter influencing yield and pectin chemical composition. Lower pH values negatively affected the galacturonic acid content of pectin, but increased the pectin yield. The values of degree of methylation decreased significantly with increasing temperature and time of extraction. The average molecular weight ranged widely from 87 to 248kDa and was mainly influenced by pH and extraction time.

Dietary fibre components and pectin chemical features of peels during ripening in banana and plantain varieties

The effects of the ripeness stage of banana ( Musa AAA) and plantain ( Musa AAB) peels on neutral detergent fibre, acid detergent fibre, cellulose, hemicelluloses, lignin, pectin contents, and pectin chemical features were studied. Plantain peels contained a higher amount of lignin but had a lower hemicellulose content than banana peels. A sequential extraction of pectins showed that acid extraction was the most efficient to isolate banana peel pectins, whereas an ammonium oxalate extraction was more appropriate for plantain peels. In all the stages of maturation, the pectin content in banana peels was higher compared to plantain peels. Moreover, the galacturonic acid and methoxy group contents in banana peels were higher than in plantain peels. The average molecular weights of the extracted pectins were in the range of 132.6–573.8 kDa and were not dependant on peel variety, while the stage of maturation did not affect the dietary fibre yields and the composition in pectic polysaccharides in a consistent manner. This study has showed that banana peels are a potential source of dietary fibres and pectins.

Banana streak virus Identified for the First Time in Peru in Cavendish Banana (Musa AAA).

In October of 2005, a field survey was done in the province of Piura in northern Peru to determine the cause of a disease known locally as "mosaico" that was affecting organic Cavendish banana (Musa AAA) grown for the export market. Disease symptoms consisted of pronounced chlorotic and necrotic lesions on leaves of affected plants. Twenty-four farms were visited, and at each location, 10 randomly selected plants at flowering stage were evaluated for disease incidence and severity. Plants showing virus-like symptoms were observed in 18 of the 24 locations (75%). Fifty-two banana leaf samples, 27 from plants showing virus-like symptoms and 25 from asymptomatic plants, were tested for the presence of Banana streak virus (BSV), Cucumber mosaic virus (CMV), and Banana mild mosaic virus (BanMMV) by immunosorbent electron microscopy (ISEM) using partially purified leaf tissue extracts (2).The same extracts were also tested by immunocapture PCR (IC-PCR) for presence of BSV and specific BSV isolates (BSV-OL, BSV-GF, BSV-IM, and BSV-CAV) using badnavirus-specific degenerate primers and BSV isolate-specific primers, respectively (1). Seventeen of 27 leaf samples showing virus-like symptoms (63%) tested positive for BSV by ISEM and IC-PCR using badnavirus, but not isolate-specific, primers. The symptoms on the 10 samples that tested negative were not typical of BSV infection. One asymptomatic leaf sample (4%) also tested positive for BSV. To validate the PCR results, the nucleotide sequence of the amplicon from a plant showing the most prevalent foliar symptom type was determined. This sequence (GenBank Accession No. DQ674317) had ≤86% homology to the corresponding ORF III polyprotein region of BSV and other badnaviruses. Neither CMV nor BanMMV was detected in any of the 52 samples tested. From these results, it was concluded that "mosaico" disease of organic Cavendish bananas in northern Peru is associated frequently with BSV infection and that there is a high incidence of BSV infection in this area. To our knowledge, this is the first report of BSV occurrence in Peru. It was both surprising and interesting that neither BSV-OL nor BSV-GF, the two BSV isolates found most commonly in banana (Musa AAA) and plantain (Musa AAB) in South and Central America (B. E. L. Lockhart, unpublished), was detected in Cavendish banana in northern Peru. Failure to detect BSV-OL and BSV-GF suggests that field infection may be due to vertical transmission by clonal propagation rather than to horizontal transmission from local plantain and that control of "mosaico" disease could therefore be achieved by use of virus-free planting material.

Effects of cinnamon extract, chitosan coating, hot water treatment and their combinations on crown rot disease and quality of banana fruit

The antifungal activities of cinnamon extract (CE), piper extract (PE) and garlic extract (GE) were evaluated on banana crown rot fungi ( Colletotrichum musae, Fusarium spp. and Lasiodiplodia theobromae) in vitro. The assay was conducted with extracts of CE, PE and GE with concentrations of 0, 0.1, 0.5, 1.0, 5.0, 10.0 and 0.75 g L −1 of carbendazim (CBZ) on potato dextrose agar at room temperature. CE completely inhibited conidial germination and mycelial growth of all fungi at 5.0 g L −1. PE totally suppressed mycelial growth of all fungi at 5.0 g L −1 and conidial germination at 10.0 g L −1 except for Fusarium spp. GE had no significant effects but low concentrations (0.1 and 0.5 g L −1) enhanced germ tube elongation of the three fungi. The ED 50 values were higher for mycelial growth than for conidia except for Fusarium spp. Combined treatments were investigated on crown rot development in banana fruit ( Musa AAA group ‘Kluai Hom thong’). Treatments included 5.0 g L −1 CE, 1% (w/v) chitosan solution, hot water treatment (HWT, 45 °C for 20 min), CE plus chitosan, CE plus HWT and 0.75 g L −1 of CBZ, applied before and after inoculation of the fruit. Crown rot development was assessed during storage at 13 °C for 7 weeks. Disease development was least (25%) on CE treated fruit after inoculation compared to CBZ but was higher when CE was applied before inoculation. Chitosan significantly delayed ripening as in terms of peel color, firmness, soluble solids and disease severity. CE showed no negative effects on quality of fruit. CE plus HWT caused unacceptable peel browning.

First report of plantain zonate leaf spot caused byPestalotiopsis menezesianain China

Plantain zonate leaf spot, caused by Pestalotiopsis menezesiana, was found for the first time in China on a plantation at Jinling town of Nanning city, Guangxi province in 2005. The fungus was isolated and pathogenicity confirmed. The fungus was sensitive to prochloraz, iprodione, thiabendazole and triazole fungicides in vitro. Pathogenicity tests showed that the pathogen could infect banana cultivars (Musa AAA) as well as plantain (Musa AAB) under artificial inoculation conditions. However, the disease could only be found on the leaves of plantain in the fields. This is the first record of Pestalotiopsis menezesiana on plantain in China.

Triploid banana cell growth phases and the correlation of medium pH changes with somatic embryogenesis in embryogenic cell suspension culture

Embryogenic cell suspensions of Musa AAA and AAB genomic groups were cultured in a maintenance culture medium for 17 generations (lasting for 238 days). The cell growth phases and medium pH changes were also observed correspondingly. Three major growth phases of AAA genomic group have been focused, namely cell releasing, proliferation and globularization phases. During almost all the subculture generations the cell stocks of AAB ‘Raja’ were continuously characterized by proliferating cell aggregates while the globularization phase occurred only for short duration. The medium acidity levels of the cell stocks of AAA ‘Pei-Chiao’ and ‘Robusta’ were commonly scattered in a wider range of pH 3.3–5.3, while the AAB ‘Raja’ were deviated in a narrow range of pH 4.0–4.6. After subculture, culture medium showed biphasic pH changes, which were drastic pH falls followed by an auto-regulated steady-state level. The steady-state pH values in each of the three growth phases (i.e. cell releasing, proliferation and globularization phases) were of 3.3–4.0, 4.0–4.8 and 4.8–5.3 respectively. Morphological bipolarity and the efficiency in the formation of somatic embryos have been thoroughly discussed. Reported research indicates that the condition of pH below 4.6 may prevent the development of embryogenic cells towards polar growth.

Effects of the stage of maturation and varieties on the chemical composition of banana and plantain peels

A study of the chemical composition of six varieties of fruit peels of the banana and plantain: dessert banana ( Musa AAA), plantain ( Musa AAB) cooking banana ( Musa ABB) and hybrid ( Musa AAAB) at three stages of ripeness, was carried out in order to explore their potential applications. The varieties did not affect chemical constituents in a consistent manner. Peel of the six varieties was rich in total dietary fibre (TDF) (40–50%). The protein content in peel of the banana and plantain was 8–11%. Leucine, valine, phenylalanine and threonine were essential amino acids in significant quantities. Lysine was the limiting amino acid. The content of lipid varied from 2.2% to 10.9% and was rich in polyunsaturated fatty acids, particularly linoleic acid and α-linolenic acid. Potassium was the most significant mineral element. Peel of plantain was richer in starch than were the banana peels. Maturation of fruits involved increase in soluble sugar content and, at the same time, decrease in starch. The degradation of the starch under the action of the endogenous enzymes, may explain the increase in the soluble sugar content. Further investigations on the composition and the physiological functions (using animal-feeding experiments) of these dietary fibres must be considered.

Field Performance of Micropropagated East African Banana (Musa AAA East Africa) in the Eastern Zone of Tanzania

This study was conducted to evaluate yield performance of micro-propagated (MPd) East African cooking banana (Musa AAA East Africa) cv. 'Uganda' and cv. 'Bukoba' in the Eastern zone of Tanzania. Plant size of MPd cv. 'Bukoba' was significantly bigger (p0.05) with pseudostem height, girth and height to girth ratio of 425.4, 67.0 cm and 6.4 compared to 370.6, 59.5 cm and 6.1 of the conventionally propagated (CPd) banana, respectively. Moreover, plant crops of MPd cv. 'Uganda' and 'Bukoba' were harvested 29 and 27 days earlier compared to the plant crops of CPd banana, respectively. On the other hand, plant crop of MPd cv. 'Bukoba' produced smaller (p0.05) bunches and fruits weighing 14.4 kg and 138.5 g compared to 23.9 kg and 146.2 g of the plant crop of CPd banana, respectively. Similarly, ratoon crops of MPd cv. 'Bukoba' produced lower bunch and fruit weight than those of CPd banana. The low bunch yield of the MPd cv. 'Bukoba' could be due to reduction in fruit weight. Plant crop of MPd cv. 'Uganda' produced more uniform fruits in terms of weight, length and girth whereas that of MPd cv. 'Bukoba' produced more uniform fruits in terms of weight and girth. Fruit size uniformity was insignificantly different in subsequent ratoon crops of both cultivars. Further studies are required to determine causes and bases of lower yield in MPd cv. 'Bukoba'. (Author's abstract).

Effects of the Physiological Age of Bananas on Their Susceptibility to Wound Anthracnose Due to Colletotrichum musae.

Wound anthracnose, caused by Colletotrichum musae, and early ripening are the main problems affecting the quality of export bananas (Musa AAA Cavendish) from the Caribbean. These problems generally concern bananas grown in lowland plantations during the rainy season. Three experiments were carried out to study the influence of the physiological age of bananas, calculated on the basis of mean daily temperature sums, on their susceptibility to anthracnose. Stressful growing conditions, especially soil flooding, slowed fruit growth but had no direct effect on fruit susceptibility to C. musae or on the green life. However, fruit that had accumulated lower temperature sums were less susceptible to wound anthracnose. By varying the source-sink ratio, we show that bananas of the same grade but different physiological ages had markedly different susceptibility to C. musae. Bananas with the same temperature sum accumulation but grown in different soil-climate conditions had different levels of susceptibility. Fruit grown in cooler, highland areas were less susceptible to C. musae than fruit of the same physiological age from lowland plantations. Our results suggest that temperature sum accumulation rate is a critical factor affecting the susceptibility of bananas to the pathogen.

The effect of plant growth regulators on somaclonal variation in Cavendish banana ( Musa AAA cv. ‘Z elig’)

The effect of the type and concentration of plant growth regulators and sub-culturing on somaclonal variation were studied in Cavendish banana cv. ‘ Zelig’ obtained from African Biotechnologies Ltd., South Africa. In vitro grown plants at the fourth multiplication cycle were used for the investigation. Auxins (IAA, IBA and NAA) and cytokinins (BA and TDZ) were used to multiply shoots for 10 generations. Bands generated through RAPD-PCR were scored according to whether they were present (1) or absent (0) to determine the extent of somaclonal variation. Results were then analyzed using cluster analysis. The relationship between multiplication rate and somaclonal variation was assessed using correlation analysis. Results indicated that treatments with higher multiplication rates produced more variants; sometimes as high as 72%. Dwarf off-types accounted for 88% of the variation. A dwarf-specific band, about 1500 kb in size, was amplified by the primer OPC-15. The band appeared consistently in normal plants but was absent in all dwarf plants.

Frequency of occurrence and abundance of root nematodes on banana (Musa AAA) in Belize

An analysis of plant-parasitic nematodes occurring in all the 21 commercial banana (Musa AAA) plantations in Belize from 1999 to 2004 was undertaken. Nematode extraction was done using 25 g of fresh roots macerated in a kitchen blender, followed by recovering the nematodes with a 0.038-mm sieve. Frequency was calculated as a percentage (number of samples containing a species/number of samples collected × 100). Two plant-parasitic nematode species were detected, and based on their frequencies and population densities their relative importance was established as: Radopholus similis > Helicotylenchus multicinctus. Radopholus similis was the most abundant species, accounting for 56 – 84% of the overall root nematode population throughout each study year. From a total of 1508 root samples, 1401 (93%) contained R. similis and 1324 (88%) H. multicinctus, and when the nematodes present in the samples were pooled (total nematodes) only 39 (3%) of the samples were free of nematodes. High populations of R. similis were found in all years and months of the survey.