Exogenous progesterone treatment alleviates chilling injury in postharvest banana fruit associated with induction of alternative oxidase and antioxidant defense.

The effects of exogenous progesterone (PROG) on chilling injury (CI) in postharvest banana fruit were investigated. Concentration screening tests showed that 10-5 mol/l PROG was most effective in reducing CI in banana fruit stored for 25 d at 5 ±â€¯1 °C, but did not markly increase PROG content of pulps. This PROG treatment significantly reduced the electrolyte leakage, levels of malondialdehyde, O2- production rate and H2O2 contents in banana compared with control fruit. The PROG treatment caused an early induction of alternative oxidase (AOX) at the transcript and protein level to reduce the generation of O2- and H2O2. PROG treatment also enhanced the transcript levels and activities of antioxidant enzymes and maintained higher levels of reduced glutathione and ascorbic acid than the control fruit. These results suggested that PROG attenuating CI in banana fruit may be attributed to the induction of AOX and the improvement of enzyme and non-enzymatic antioxidant defenses.

Microencapsulação de frutos de Musa cv. Vitória / Frutas microencapsulación de Musa cv. Vitória / Microencapsulation of fruits of Musa cv. Vitória

Introdução: Musa sp., Musaceae, conhecida como bananeira, abundante no Brasil sendo utilizada para fins alimentares. Objetivos: microencapsular extratos de frutos de Musa sp. visando o desenvolvimento de material-prima enriquecida de polifenóis para formulação de alimentos funcionais. Métodos: os frutos de Musa cv. Vitória foram fornecidos pelo Incaper (Instituto Capixaba de Pesquisa, Assistência Técnica e Extensão Rural). Empregou-se extrato hidroalcóolico acidificado de frutos de banana. Determinações de polifenóis totais, taninos e flavonoides foram realizadas por método colorimétrico de Folin-Ciocalteau e complexação com cloreto de alumínio. A avaliação do potencial antioxidante foi realizada por ensaio de redução do radical 2,2-diphenyl-1-picrylhydrazyl. Microencapsulação realizada com dois biopolímeros. Fez-se uma análise de conservação de fenólicos com os microencapsulados. Os resultados foram submetidos à análise de variância e as médias comparadas pelo teste de Tukey (p < 0,05) e pelo teste de Mann-Whitney (p < 0,05). Resultados: a quantificação de fenólicos totais foi de 251,98 ± 0,1 mg/g de amostra e de taninos foi de 179,89 ± 0,01 mg/g de amostra. O teor de flavonoides totais foi abaixo do limite de quantificação. A atividade antioxidante por redução do radical 2,2-diphenyl-1-picrylhydrazyl teve CI50 > 5 mg/mL. A quantificação inicial nas microcápsulas em goma arábica de polifenóis totais e apresentou-se maior quando comparada à maltodextrina. Após o armazenamento do material, 12 dias, a -5 ºC, a goma arábica preservou os polifenóis e taninos em comparação à maltodextrina. Conclusões: pode-se empregar o extrato Musa cv. para matéria-prima como fonte de fenólicos totais e taninos. Em comparação dos biopolímeros utilizados, demonstrou-se que a maltodextrina tem menor capacidade de conservação de fenólicos totais e taninos(AU)

Introducción: Musa sp., Musaceae, conocido como plátano, abundante en Brasil se utiliza para fines alimenticios. Objetivos: microencapsular extractos de frutas microencapsulado de Musa sp. para el desarrollo de la materia prima enriquecida con polifenoles para la formulación de los alimentos funcionales. Métodos: los frutos de Musa cv. Vitória fueron proporcionados por Incaper (Capixaba Instituto de Investigación, Asistencia Técnica y Extensión Rural), Espírito Santo, Brasil. Preparación del extracto hidroalcohólico acidificado de frutos de plátano verde. Determinación de polifenoles totales, taninos y flavonoides fueron realizadas por colorimétria de Folin-Ciocalteu y complejación con cloruro de aluminio. Se realizó la evaluación del potencial antioxidante mediante el ensayo de reducción radical 2,2-difenil-1-picrilhidracilo. La microencapsulación se realiza con dos biopolímeros. Hubo un análisis de la conservación fenólico con microencapsulado. Los resultados fueron sometidos a análisis de varianza y las medias se compararon mediante la prueba de Tukey (p <0,05) y pela prueba de Mann-Whitney (p <0,05). Resultados: la cuantificación de fenoles totales fue 251,98 ± 0,1 mg/g de muestra y taninos fue 179,89 ± 0,01 mg/g de muestra. El contenido total de flavonoides estaba por debajo del límite de cuantificación. La actividad antioxidante por reducción radical 2,2-difenil-1-picrilhidracilo tenía IC50> 5 mg/mL. La cuantificación de los polifenoles totales y taninos que comienzan con el material microencapsulado acacia presentado sea mayor que con maltodextrina. Después del almacenamiento del material a -5 °C se cuantificó fenoles totales y taninos. La cuantificación de la maltodextrina ha demostrado una mayor pérdida de metabolitos. Conclusiones: se puede emplear el extracto de Musa cv. para materia-prima como fuente de fenoles totales y taninos. En biopolímeros de comparación utilizado, se demostró que la maltodextrina tiene una menor capacidad para preservar fenoles totales y taninos(AU)

Introduction: Musa sp., Musaceae, known as banana, abundant in Brazil being used for food purposes. Objectives: To microencapsulate fruit extracts of Musa cv. Vitória, for the development of raw material enriched with polyphenols for formulation of functional foods. Methods: The fruits of Musa cv. Vitória were provided by Incaper (Capixaba Institute of Research, Technical Assistance and Rural Extension). We applied acidified hydroalcoholic extract of banana fruit. Determinations of total polyphenols, tannins and flavonoids were performed by colorimetric method of Folin-Ciocalteu method and, complexation with aluminum chloride. Evaluation of antioxidant activity assay was performed by reduction of the radical 2.2-diphenyl-1-picrylhydrazyl. Microencapsulation performed with two biopolymers. There was a phenolic analysis with conservation microencapsulated. Data were analyzed by analysis of variance and means compared by Tukey test and by Mann-Whitney test (p < 0.05). Results: The quantification of total phenolics and tannins was 251.98 ± 0.1 mg / g sample and 179.89 ± 0.01 mg / g sample, respectively. The total flavonoid content was below the limit of quantification. The antioxidant activity by DPPH had IC50 > 5 mg / mL. The initial quantification in microcapsules in gum arabic total polyphenols and was higher compared to maltodextrin. After storage of the material 12 days, -5 °C, gum arabic preserved polyphenols and tannins compared to maltodextrin. Conclusion: Can use the Musa cv. extract for raw materials as a source of total phenolics and tannins. In comparison of biopolymers used, it was demonstrated that the maltodextrin has a lower retention capacity for total phenolics and tannins(AU)

Thermotherapy, chemotherapy, and meristem culture in banana.

Bananas that provide a staple food to the millions of people are adversely affected by several viruses such as Banana bunchy Top Virus (BBTV), Banana Streak Virus (BSV), and Cucumber Mosaic Virus (CMV). These viruses are known to have a devastating effect on crop production and constraint to the international exchange and conservation of banana germplasm-a cornerstone for breeding new cultivars. The viruses are particularly problematic in vegetative propagated crops, like bananas, because of their transmission in the planting material. Different virus eradication techniques have been developed, such as thermotherapy, chemotherapy, and meristem culture for providing virus-free planting material. Meristem culture proved to be the most effective procedure to eradicate phloem-associated viruses. This method requires isolation of meristematic dome of plant under the aseptic conditions and culture in an appropriate nutrient medium to develop new virus-free plants. Thermotherapy is another widely used virus eradication technique, which is initially carried out on in vivo or in vitro plants and eventually combined with meristem culture technique. The plantlets are initially grown at 28°C day temperature and increase it by 2°C per day until reaches 40°C and the night temperature at 28°C; maintain plants at 40°C for 4 weeks; excise meristem and culture onto the regeneration medium. In chemotherapy technique, antiviral chemical compound Virazole(®) is applied on meristem culture. Combination of these techniques is also applied to improve the eradication rate.

The role of meta-topolins on the photosynthetic pigment profiles and foliar structures of micropropagated 'Williams' bananas.

The effect of five topolins (meta-Topolin=mT; meta-Topolin riboside=mTR; meta-Methoxy topolin=MemT; meta-Methoxy topolin riboside=MemTR and 6-(meta-methoxy)-9-(tetrahydropyran-2-yl)-topolin=MemTTHP) on the photosynthetic pigments and leaf structures of micropropagated 'Williams' bananas was compared with the commonly used benzyladenine (BA). Surface-decontaminated explants were cultured for 70 d on modified Murashige and Skoog (MS) basal medium and supplemented with 10, 20 or 30µM cytokinins (CKs). At 10 d intervals, the photosynthetic pigments were quantified via spectrophotometric methods for 7 cycles. Generally, the maximum pigment content was attained between 40 and 50 d. The control plantlets had the highest pigment content (1150µg/g FW). Among the CKs, 10µM MemTTHP generally had the best pigment stimulatory effect at the same period. After 40 d, scanning electron microscopy (SEM) of the foliar surface showed that the stomata density was highest in 10µM MemTTHP-treated and lowest in 10µM MemTR-treated plantlets. The stomatal structure and pore area also varied with the type and concentration of CK added. Generally, prolonging culture duration as well as increasing CK concentrations reduced the pigment content. However, the drastic breakdown in chlorophyll pigments beyond 50 d was slightly inhibited by the presence of mT, mTR, MemTTHP and BA compared to the control. The CK-treated plantlets at equimolar concentration had comparable chlorophyll a/b and total chlorophyll/carotenoid ratios after 10 d; probably as an adaptive measure. At the end of the current study, 10µM mT and mTR plantlets remained green as reflected by the higher total chlorophyll/carotenoid ratio as well as by the visual observations. A well-developed photosynthetic apparatus enhances the survival of in vitro plantlets during the acclimatization stage. Current findings provide some insight into the role of meta-topolins on photosynthetic parameters in vitro, which inevitably partly contributed to the better acclimatization capability of meta-topolin-regenerants.

Physiological responses and endogenous cytokinin profiles of tissue-cultured 'Williams' bananas in relation to roscovitine and an inhibitor of cytokinin oxidase/dehydrogenase (INCYDE) treatments.

The effect of supplementing either meta-topolin (mT) or N(6)-benzyladenine (BA) requiring cultures with roscovitine (6-benzylamino-2-[1(R)-(hydroxymethyl)propyl]amino-9-isopropylpurine), a cyclin-dependent kinase (CDK) and N-glucosylation inhibitor, and INCYDE (2-chloro-6-(3-methoxyphenyl)aminopurine), an inhibitor of cytokinin (CK) degradation, on the endogenous CK profiles and physiology of banana in vitro was investigated. Growth parameters including multiplication rate and biomass were recorded after 42 days. Endogenous CK levels were quantified using UPLC-MS/MS while the photosynthetic pigment and phenolic contents were evaluated spectrophotometrically. The highest regeneration rate (93 %) was observed in BA + roscovitine while mT + INCYDE plantlets produced most shoots. Treatment with BA + roscovitine had the highest shoot length and biomass. Although not significant, there was a higher proanthocyanidin level in BA + roscovitine treatments compared to the control (BA). The levels of total phenolics and flavonoids were significantly higher in mT + roscovitine treatment than in the mT-treated regenerants. The presence of roscovitine and/or INCYDE had no significant effect on the photosynthetic pigments of the banana plantlets. Forty-seven aromatic and isoprenoid CKs categorized into nine CK-types were detected at varying concentrations. The presence of mT + roscovitine and/or INCYDE increased the levels of O-glucosides while 9-glucosides were higher in the presence of BA. Generally, the underground parts had higher CK levels than the aerial parts; however, the presence of INCYDE increased the level of CK quantified in the aerial parts. From a practical perspective, the use of roscovitine and INCYDE in micropropagation could be crucial in the alleviation of commonly observed in vitro-induced physiological abnormalities.

Spermine-induced morphogenesis and effect of partial immersion system on the shoot cultures of banana.

Contribution of exogenous polyamines (PAs) and polyamine-inhibitors on plantlet regeneration patterns of banana (cv. Nanjanagudu Rasabale-AAB) was studied and the performance of regenerated shoots in temporary immersion system was evaluated. The rhizome explants (without shoot bud) of in vitro shoots produced a mixture of embryogenic and nonembryogenic calli on modified MS medium. The analyses of endogenous pools of polyamines showed higher levels of PAs in embryogenic than in nonembryogenic calli. Supplementation of various levels of (10-50 microM) spermine (Spm), spermidine (Spd), and putrescine (Put) to cultures with secondary embryogenesis showed that about 50% of embryogenic calli rapidly produced secondary embryos only in the presence 40 microM Spm but not in other treatments. The crucial role of Spm was further confirmed by the use of 0.1 mM each of alpha-DL-Difluromethylornithine and alpha-DL-Difluromethylarginine along with Spm where the presence of inhibitors concomitantly inhibited the secondary embryogenesis. The shoots obtained from the embryogenic cultures were checked for their performance on solid medium (SM) and partial immersion system (PIS). The rate of shoot multiplication was higher in PIS than in SM throughout 6 weeks culture period. Uniformity in elongation of all the shoot buds was observed in PIS but not in SM. Evaluation for the acclimatization, survival under greenhouse conditions revealed the better performance of PIS-derived plants than those from SM.

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.

[Establishment of embryogenic cell suspension culture and plant regeneration of edible banana Musa acuminata cv. Mas (AA)].

Conventional breeding for dual resistance of disease and pest of Musa cultivars remains a difficult endeavor, as the plant is polyploidic and high in sterility. Biotechnological techniques, eg., genetic engineering, in vitro mutation breeding, or protoplast fusion, may overcome the difficulties and improve the germplasm. Establishment of a stable embryogenic cell suspension (ECS) is a prerequisite for any of the biotechnological breeding methods. In this study an embryogenic cell suspension was established from immature male flower of Musa acuminata cv. Mas (AA), a popular commercial variety of banana in the South-East Asian region. After culture for 5-6 months on callus induction media, which consisted of MS salts, different concentrations of 2,4-dichlorophenoxyacetic acid (2,4-D), 4.1 micromol/L biotin, 5.7 micromol/L indoleacetic acid (IAA), 5.4 micromol/L naphthaleneacetic acid (NAA), other vitamins, 87 mmol/L sucrose, and solidified with 7 g/L agarose, meristematic globules and yellow, friable embryogenic cultures were induced from the explants of 1-15th row young floral hands of immature male flowers. Of the four treatments of 2,4-D, 9 micromol/L was the most effective on the callus induction, it transformed 40.96% and 7.45% of the cultivated male floral hands into callus and embryogenic callus respectively. The explants to produce highest frequency of the embryogenic calli were floral hands of 6 to 12th rows, which generated 5.79% of the embryogenic calli. Suspension cultures were initiated from these embryogenic calli in liquid medium supplemented with 4.5 micromol/L 2, 4-D. After sieving selection of the cultures using a stainless steel metallic strainer with pore sizes of 154 microm at 15 day intervals for 3 months, homogeneous and yellow embryogenic cell suspensions, composed of single cells and small cell aggregates, were established. Based upon the growth quantity and growth rate of ECS, it was determined that the appropriate inoculum was 2.0 mL PCV ECS/30 mL medium in 100 mL flask, and the appropriate subculture cycle was 15 days. Planting of 6 months old ECS on semi-solid medium of somatic embryo induction and development (MSD) resulted in approximately 280 x 10(3) somatic embryos/mL PCV ECS. MSD contained SH macronutrients, micro-nutrients, Fe-EDTA and MS vitamins supplemented with 4.5 micromol/L biotin, 680 micromol/L glutamine, 2 mmol/L proline, 100 mg/L malt extract, 1.1 micromol/L NAA, 0.2 micromol/L zeatin, 0.5 micromol/L kinetin, 0.7 micromol/L N6-(2-isopentenyl) adenine, 29 mmol/L lactose, 130 mmol/L sucrose and solidified with 2g/L gelrite. After 3 months of maturity on MSD, 17.28% of the somatic embryos were germinated on germination media (MG), consisted of MS salt, Morel and Wetmore vitamins, 0.2 micromol/L 6-BA, 1.1 micromol/L IAA, 87 micromol/L sucrose and solidified with 2 g/L gelrite; and 14.16% of the somatic embryos could develop into normal plantlets on rooting media contained the same composition as that of MG but without auxin and cytokinin.

Effect of menadione sodium bisulfite, an inducer of plant defenses, on the dynamic of banana phytoalexin accumulation during pathogenesis.

Using an authentic sample of 2-hydroxy-9-(p-hydroxyphenyl)-phenalen-1-one, a banana phenalenone-type phytoalexin, we studied its dynamic of accumulation during pathogenesis of banana plants (Musa acuminata (AAA), Grand Nain) inoculated with Fusarium oxysporum f.sp. cubense (FOC), Race 4, the causal agent of Panama disease. The results obtained demonstrate that banana plants treated prior inoculation with menadione sodium bisulfite (MSB), an inducer of plant defenses, are capable of changing the dynamic of accumulation (higher amount and speed of biosynthesis) of this banana phytoalexin, biosynthesized by the banana plant during pathogenesis.

Ecdysteroids of Vitex scabra stem bark.

Two new ecdysteroids, 24-epi-pinnatasterone (1) and scabrasterone (2), together with 11 known ecdysteroids, calonysterone, pterosterone, 24-epi-makisterone A, 20-hydroxyecdysone (3), polypodine B, ajugasterone C, pinnatasterone (4), 11alpha-hydroxyecdysone, 24-epi-abutasterone, 20,26-dihydroxyecdysone, and turkesterone (5), were isolated from the stem bark of Vitex scabra. This plant species contained a very high concentration (1.8%) of 3 and thus provided a good source of this parent ecdysteroid and related rare ecdysteroids. Compounds 1 and 2 exhibited very low moulting activity in the Musca bioassay. The low biological activity of these two ecdysteroids was in agreement with those of other 22-deoxyecdysteroids.