Investigating aluminum toxicity effects on callose deposition, oxidative stress, and nutrient homeostasis in banana genotypes.

Aluminum (Al) toxicity poses a significant challenge to agricultural productivity, particularly in acidic soils. The banana crop, predominantly cultivated in tropical and subtropical climates, often grapples with low pH and Al toxicity. This study seeks to explore the differential responses of two banana genotypes with varying Al tolerance (Baodao and Baxi) to Al exposure (100 and 500 µM) for 24 h. Microscopic analysis uncovered distinctive structural modifications in root cells, with Baodao displaying more severe alterations in response to Al stress. There was higher superoxide (O2-.) and hydrogen peroxide (H2O2) production and lipid peroxidation in Baodao indicating enhanced oxidative stress and membrane damage. Al accumulation in root tips was higher in Baxi than Baodao, while the roots of Baodao had a higher accumulation of callose. Nutrient content analysis revealed alterations in ion levels, highlighting the impact of Al exposure on nutrient uptake and homeostasis. In summary, Al differentially affects callose deposition, which, in turn, leads to Al uptake and nutrient homeostasis alteration in two contrasting banana genotypes. This intricate interplay is a key factor in understanding plant responses to aluminum toxicity and can inform strategies for crop improvement and soil management in aluminum-stressed environments.

Total phenolics, flavonoids and antioxidant activity following simulated gastro-intestinal digestion and dialysis of banana (Musa acuminata, AAB) as affected by induced ripening agents.

The present study was conducted to evaluate effect of ethephon and acetylene treatments on phenolics, flavonoids and antioxidant activity of banana flesh and their bioaccessibility. Total phenolics, flavonoids and antioxidant activity (DPPH, ABTS, FRAP) were measured at different phases of simulated gastrointestinal digestion of banana treated with 1000 ppm ethephon and 1000 ppm acetylene against natural ripening. The results revealed that inducing ripening lowers the content of phenolics, flavonoids and antioxidant activity considerably in the fresh fruit. Bioavailability of phenolics, flavonoids and FRAP activity were increased significantly (p < 0.05) after gastric digestion regardless of the treatment. The release of polyphenols and flavonoids during gastric digestion in treated banana was more significant than in naturally ripened banana. Recovery of polyphenols after dialysis was significantly high in naturally ripened banana. Dialyzable flavonoids, DPPH and ABTS activities of dialyzed fractions were not significantly affected by ethephon or acetylene treatments.

What are the Main Sensor Methods for Quantifying Pesticides in Agricultural Activities? A Review.

In recent years, there has been an increase in pesticide use to improve crop production due to the growth of agricultural activities. Consequently, various pesticides have been present in the environment for an extended period of time. This review presents a general description of recent advances in the development of methods for the quantification of pesticides used in agricultural activities. Current advances focus on improving sensitivity and selectivity through the use of nanomaterials in both sensor assemblies and new biosensors. In this study, we summarize the electrochemical, optical, nano-colorimetric, piezoelectric, chemo-luminescent and fluorescent techniques related to the determination of agricultural pesticides. A brief description of each method and its applications, detection limit, purpose-which is to efficiently determine pesticides-cost and precision are considered. The main crops that are assessed in this study are bananas, although other fruits and vegetables contaminated with pesticides are also mentioned. While many studies have assessed biosensors for the determination of pesticides, the research in this area needs to be expanded to allow for a balance between agricultural activities and environmental protection.

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.

Identification of Ethylene Responsive miRNAs and Their Targets from Newly Harvested Banana Fruits Using High-Throughput Sequencing.

The roles of microRNAs (miRNAs) related to ethylene response in banana fruits remain unknown because many miRNAs are differentially expressed as the fruit ripens, making the identification of ethylene-responsive miRNAs difficult. Using newly harvested banana fruits (within 5 h after harvest) as material, we found that these fruit did not ripen when treated with 5 µL/L of ethylene for 12 h at 22 °C. Two miRNA libraries were generated from newly harvested banana fruits with and without ethylene treatment and sequenced. In total, 128 known miRNAs belonging to 42 miRNA families were obtained, and 12 novel miRNAs were identified. Among them, 22 were differentially expressed in response to ethylene treatment, among which 6 known miRNAs and their putative targets were validated using qRT-PCR. These putative targets encoded proteins including GATA, ARF, DLC, and AGO, etc. KEGG and GO analyses showed that miRNAs differentially expressed in response to ethylene mainly function in the molecular and biological processes.

Cryopreservation of banana's cv Grand Naine in vitro rhizomes

ABSTRACT The preservation of banana genetic material is usually performed through seedlings. However, most banana cultivars do not produce seed and are propagated vegetatively. Therefore, cryopreservation is a feasible technique that allows the preservation of banana genotypes indefinitely. For the success of cryopreservation protocols, the selection of cryoprotectants and pre-freezing techniques are important factor. Therefore, the objective of this study was to verify the effects of different cryoprotectants with and without 1% phloroglucinol and pre-cooling periods on the development of a protocol for cryopreservation of in vitro rhizomes ofMusa accuminata(AAA) cv Grand Naine banana. The addition of 1% phloroglucinol to the cryoprotective solutions, such as PVS2 enhanced recovery of cryopreserved banana rhizomes. In addition, pre-cooling of explants in ice for 3 hours in PVS2 + 1% of phloroglucinol allowed efficient cryopreservation of banana rhizomes, followed by successful recovery and regeneration of in vitro shoots of banana cv Grand Naine.

Thap Maeo bananas: Fast ripening and full ethylene perception at low doses.

Brazil is a major producer and consumer of various banana types. Thap Maeo is a promising cultivar for the market due to its resistance to Black and Yellow Sigatoka disease. However, a lack of information and postharvest technologies concerning Thap Maeo physiology seems to be a significant problem limiting its expansion in the market. Thus, this study aims to establish Thap Maeo fruit's physical, biochemical, and physiological aspects, defining the best ethylene dosage for treatment considering fruit ripening parameters. Bananas were harvested and monitored during both natural and ethylene-induced ripening processes. Assessments of pulp firmness, peel color and endogenous ethylene production showed different profiles between ethylene-treated and non-treated fruits, whereas the ethylene responses concerning the carbohydrates and hormones profiles, as well as the ethylene receptors expression, were observed in all ethylene-treated fruits, even applying low concentrations of the hormone. It thus indicated the high ethylene-sensitivity of Thap Maeo cultivar. Such postharvest behaviors reverberate in lower ethylene requirements for treatment, which was established at 10µLL-1. Ethylene-inducible changes in fruit volatile compounds throughout ripening are also discussed.

Suitability of combination of calcium propionate and chitosan for preserving minimally processed banana quality.

BACKGROUND: The marketability of fresh-cut banana slices is limited by the rapid rate of fruit softening and browning. However, there is no scientific literature available about the role of postharvest calcium propionate and chitosan treatment on the quality attributes of fresh-cut banana. Therefore, the aim of the present study was to investigate these effects. RESULTS: The application of calcium propionate plus chitosan (CaP+Chit) retained higher firmness, higher ascorbic acid content, higher total antioxidant activity and higher total phenolic compounds, along with lower browning, lower polyphenol oxidase, lower peroxidase, lower polygalacturonase and lower pectin methyl esterase activities and microbial growth, compared to control banana slices after 5 days of cold storage. CONCLUSION: The results of the present study show that CaP+Chit could be used to slow the loss of quality at the same time as maintaining quality and inhibiting microbial loads. © 2017 Society of Chemical Industry.

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)

Benzothiadiazole-Mediated Induced Resistance to Colletotrichum musae and Delayed Ripening of Harvested Banana Fruit.

Benzothiadiazole (BTH) works as a plant activator. The effects of different BTH treatments and fungicides SPORGON on fruit ripening and disease incidence were investigated. The results showed that BTH treatment significantly delayed fruit ripening, maintained fruit firmness, color, and good fruit quality, and dramatically reduced the incidence of disease. BTH effectively inhibited the invasion and development of pathogenic bacteria and controlled the occurrence of disease. BTH treatment enhanced the activities of defense-related enzymes, including chitinase, phenylalanine ammonia-lyase, peroxidase, and polyphenol oxidase, increased the content of hydrogen peroxide and total antioxidant capacity, and reduced malondialdehyde content. Cellular structure analysis after inoculation confirmed that BTH treatment effectively maintained the cell structural integrity. SPORGON did not provide benefits for delaying fruit ripening or for the resistance system, while it can control the disease only during the earlier stage and not at later stages.

Banana fruit NAC transcription factor MaNAC5 cooperates with MaWRKYs to enhance the expression of pathogenesis-related genes against Colletotrichum musae.

Plants respond to pathogen attack by the modulation of a large set of genes, which are regulated by different types of transcription factor (TF). NAC (NAM/ATAF/CUC) and WRKY are plant-specific families of TFs, and have received much attention as transcriptional regulators in plant pathogen defence. However, the cooperation between NAC and WRKY TFs in the disease response remains largely unknown. Our previous study has revealed that two banana fruit WRKY TFs, MaWRKY1 and MaWRKY2, are involved in salicylic acid (SA)- and methyl jasmonate (MeJA)-induced resistance against Colletotrichum musae via binding to promoters of pathogenesis-related (PR) genes. Here, we found that MaNAC1, MaNAC2 and MaNAC5 were up-regulated after C. musae infection, and were also significantly enhanced by SA and MeJA treatment. Protein-protein interaction analysis showed that MaNAC5 physically interacted with MaWRKY1 and MaWRKY2. More importantly, dual-luciferase reporter (DLR) assay revealed that MaNAC5, MaWRKY1 and MaWRKY2 were transcriptional activators, and individually or cooperatively activated the transcriptional activities of MaPR1-1, MaPR2, MaPR10c and MaCHIL1 genes. Collectively, our results indicate that MaNAC5 cooperates with MaWRKY1 and MaWRKY2 to regulate the expression of a specific set of PR genes in the disease response, and to contribute at least partially to SA- and MeJA-induced pathogen resistance.

Endogenous cytokinin profiles of tissue-cultured and acclimatized 'Williams' bananas subjected to different aromatic cytokinin treatments.

Endogenous cytokinin (CK) levels of in vitro-cultured and greenhouse-acclimatized 'Williams' bananas treated with six aromatic CKs were quantified using UPLC-MS/MS. The underground parts had higher endogenous CK levels than the aerial parts. Control plantlets had more isoprenoid CKs while the aromatic-type CKs were predominant in all other regenerants. Following acclimatization of the control and 10 µM CK regenerants, there was a rapid decline in both isoprenoid and aromatic CK in the greenhouse-grown plants. Apart from the control and 6-(3-Methoxybenzylamino)-9-tetrahydropyran-2-ylpurine (MemTTHP) treatment with higher level of isoprenoid CK, aromatic CK remain the predominant CK-type across all CK treatments. The most abundant CK forms were meta-topolin (mT) and benzyladenine (BA) in the micropropagated and acclimatized plants, respectively. Micropropagated plantlets had cis-Zeatin (cZ) as the major isoprenoid CK-type which was in turn replaced by isopentenyladenine (iP) upon acclimatization. On a structural and functional basis, 9-glucoside, a deactivation/detoxicification product was the most abundant and mainly located in the underground parts (micropropagation and acclimatization). The results establish the wide variation in metabolic products of the tested aromatic CKs during micropropagation and acclimatization. The findings are discussed with the possible physiological roles of the various CK constituents on the growth and development of banana plants.

Molecular characterization of cold-responsive basic helix-loop-helix transcription factors MabHLHs that interact with MaICE1 in banana fruit.

Basic helix-loop-helix (bHLH) transcription factors (TFs) are ubiquitously involved in the response of higher plants to various abiotic stresses. However, little is known about bHLH TFs involved in the cold stress response in economically important fruits. Here, five novel full-length bHLH genes, designated as MabHLH1-MabHLH5, were isolated and characterized from banana fruit. Gene expression profiles revealed that MabHLH1/2/4 were induced by cold stress and methyl jasmonate (MeJA) treatment. Transient assays in tobacco BY2 protoplasts showed that MabHLH1/2/4 promoters were activated by cold stress and MeJA treatments. Moreover, protein-protein interaction analysis demonstrated that MabHLH1/2/4 not only physically interacted with each other to form hetero-dimers in the nucleus, but also interacted with an important upstream component of cold signaling MaICE1, with different interaction domains at their N-terminus. These results indicate that banana fruit cold-responsive MabHLHs may form a big protein complex in the nucleus with MaICE1. Taken together, our findings advance our understanding of the possible involvement of bHLH TFs in the regulatory network of ICE-CBF cold signaling pathway.

Biochemical markers assisted screening of Fusarium wilt resistant Musa paradisiaca (L.) cv. puttabale micropropagated clones.

An efficient protocol was standardized for screening of panama wilt resistant Musa paradisiaca cv. Puttabale clones, an endemic cultivar of Karnataka, India. The synergistic effect of 6-benzyleaminopurine (2 to 6 mg/L) and thidiazuron (0.1 to 0.5 mg/L) on MS medium provoked multiple shoot induction from the excised meristem. An average of 30.10 +/- 5.95 shoots was produced per propagule at 4 mg/L 6-benzyleaminopurine and 0.3 mg/L thidiazuron concentrations. Elongation of shoots observed on 5 mg/L BAP augmented medium with a mean length of 8.38 +/- 0.30 shoots per propagule. For screening of disease resistant clones, multiple shoot buds were mutated with 0.4% ethyl-methane-sulfonate and cultured on MS medium supplemented with Fusarium oxysporum f. sp. cubense (FOC) culture filtrate (5-15%). Two month old co-cultivated secondary hardened plants were used for screening of disease resistance against FOC by the determination of biochemical markers such as total phenol, phenylalanine ammonia lyase, oxidative enzymes like peroxidase, polyphenol oxidase, catalase and PR-proteins like chitinase, beta-1-3 glucanase activities. The mutated clones of M. paradisiaca cv. Puttabale cultured on FOC culture filtrate showed significant increase in the levels of biochemical markers as an indicative of acquiring disease resistant characteristics to FOC wilt.

Molecular characterization of banana NAC transcription factors and their interactions with ethylene signalling component EIL during fruit ripening.

The plant-specific NAC (NAM, ATAF1/2, and CUC2) transcription factors (TFs) play important roles in plant growth, development, and stress responses. However, the precise role of NAC TFs in relation to fruit ripening is poorly understood. In this study, six NAC genes, designated MaNAC1-MaNAC6, were isolated and characterized from banana fruit. Subcellular localization showed that MaNAC1-MaNAC5 proteins localized preferentially to the nucleus, while MaNAC6 was distributed throughout the entire cell. A transactivation assay in yeast demonstrated that MaNAC4 and MaNAC6, as well as their C-terminal regions, possessed trans-activation activity. Gene expression profiles in fruit with four different ripening characteristics, including natural, ethylene-induced, 1-methylcyclopropene (1-MCP)-delayed, and a combination of 1-MCP with ethylene treatment, revealed that the MaNAC genes were differentially expressed in peel and pulp during post-harvest ripening. MaNAC1 and MaNAC2 were apparently upregulated by ethylene in peel and pulp, consistent with the increase in ethylene production. In contrast, MaNAC3 in peel and pulp and MaNAC5 in peel were constitutively expressed, and transcripts of MaNAC4 in peel and pulp and MaNAC6 in peel decreased, while MaNAC5 or MaNAC6 in pulp increased slightly during fruit ripening. Furthermore, the MaNAC2 promoter was activated after ethylene application, further enhancing the involvement of MaNAC2 in fruit ripening. More importantly, yeast two-hybrid and bimolecular fluorescence complementation analyses confirmed that MaNAC1/2 physically interacted with a downstream component of ethylene signalling, ethylene insensitive 3 (EIN3)-like protein, termed MaEIL5, which was downregulated during ripening. Taken together, these results suggest that MaNACs such as MaNAC1/MaNAC2, may be involved in banana fruit ripening via interaction with ethylene signalling components.

[The effect of physiologically active compounds on the production of ethylene and the activity of polygalacturonase inhibiting protein in fruits].

The treatment of apple and banana fruits with 2-CEFA and ethacyde induced the production of ethylene and accelerated the ripening and accumulation of ACC in apple fruits. Inhibitors AOA, AVG, and CoCl2 acted at the different steps of ethylene biosynthesis, inhibited the physiological aging process and increased storage longevity. Treatment with astaxantine and BOA delayed the pick of ethylene production by fruits. The content of PGIP was correlated with intensity of ethylene production. The infection of fruits with phytopathogenic microorganisms lowered as the result of the inhibition of pathogen PG. The dynamics of PGIP activity in fruits suggests its important role in the processes of ripening.

Efficiency of boron application in an Oxisol cultivated with banana in the Central Amazon

In the Amazon region, there is no information on the fertilization of banana plants with boron (B). Besides this, the extractant (hot water) currently used to test B concentrations has many limitations. The aim of this work was to study the effect of B on the fruit yield and quality of banana plants of the Cavendish (AAA) sub-group, grown in dystrophic Yellow Latosol (Oxisol or Xanthic Ferralsol), in the Amazonas State, Brazil. The experimental design was completely randomized split plot in a 4 x 2 factorial scheme, composed of four B rates (0, 4, 8 and 12 kg ha-1) and two harvest cycles (sub-treatments), with four replicates. The B availability in the soil was determined by three extractants: Mehlich 3, hot water and KCl 1.0 mol L-1. The application of B influences the fruit yield, pulp/peel ratio, pulp resistance and B content in the leaves and fruits. The KCl 1.0 mol L-1 extractant was similar to the hot water in the evaluation of available B. To obtain maximum yield, it is necessary to apply 4.1 and 6.1 kg ha-1 of B in the first and second cycles, respectively.

Na Amazônia não existem informações sobre adubação com boro (B) na bananeira, além disso, o extrator água quente, que é atualmente o mais utilizado, apresenta inúmeras limitações. O objetivo deste trabalho foi estudar o efeito do B sobre a produção e qualidade dos frutos da bananeira do subgrupo Cavendish (AAA), cultivada em Latossolo Amarelo distrófico, no Estado do Amazonas, Brasil. O delineamento experimental utilizado foi o inteiramente casualizado em parcela subdividida em esquema fatorial 4 x 2, constituído por quatro doses de B (0, 4, 8 e 12 kg ha-1) e dois ciclos de colheita - sub-parcelas (primeiro e segundo ciclo), com quatro repetições. A disponibilidade de B no solo foi determinada pelos extratores Mehlich 3, água quente e KCl 1,0 mol L-1. A aplicação de B influenciou a produção, relação polpa e casca, resistência da polpa e o teor de B nas folhas e nos frutos. O extrator KCl 1,0 mol L-1 foi semelhante ao água quente na avaliação do B disponível. Para obtenção do máximo potencial de produção é necessário aplicar 4,1 e 6,1 kg ha-1 de B no primeiro e no segundo ciclo, respectivamente.

Development of the banana plants 'Prata Anã' and 'FHIA-01' under the effect of paclobutrazol applied on the soil

Under some cultivation conditions, excessive growth of the pseudostem of banana plants can be considered a limiting factor, and thus, the use of growth regulators can constitute a valid alternative. This work aimed to evaluate the action of paclobutrazol on the growth of the pseudostem of banana plants and other characteristics of their development. An experiment was installed with five paclobutrazol doses (0; 0.5; 1.0; 1.5; and 2.0 g of a.i. plant-1) combined with two banana plant cultivars ('Prata Anã' and 'FHIA-01'). Paclobutrazol did not affect the number of days from planting to flowering, total leaf area and leaf emission rate. However, it increased leaf permanence on the plants and sucker number, reduced the foliar area of the leaves emitted after its application and provided an average reduction in pseudostem height of 26 percent.

Em algumas condições de cultivo o crescimento excessivo do pseudocaule de bananeiras pode ser considerado um fator limitante, assim a utilização de reguladores de crescimento pode constituir uma alternativa. O presente trabalho teve por objetivo avaliar a ação do paclobutrazol sobre o crescimento do pseudocaule de bananeiras e outras características do seu desenvolvimento. Para isso foi instalado um experimento com cinco doses do paclobutrazol (0; 0,5; 1,0; 1,5; e 2,0 g de i.a.planta-1) combinadas com dois cultivares de bananeira ('Prata Anã' e 'FHIA-01'). O paclobutrazol não afetou o número dedias do plantio ao florescimento, a área foliar total e a taxade emissão de folhas. Contudo, aumentou a permanência das folhas nas plantas e o número de perfilhos, reduziu a área foliar das folhas emitidas após a sua aplicação e proporcionou uma redução média de 26 por cento na altura do pseudocaule.

[The effect of ethylene biosynthesis regulators on metabolic processes in the banana fruits in various physiological states].

The effects of ethylene-evolving preparations-2-chloroethylphosphonic acid (2-CEPA), the new generation binary preparation ethacide, and the specific inhibitor of ethylene biosynthesis aminooxyacetic acid (AOA)--on the ethylene evolution by banana (Musa sp.) fruits at various ripening stages and the content of protein inhibitor of polygalacturonase (PIPG), associated with prevention of fruit tissue softening, were studied. It was demonstrated that the ripening stage was of significant importance for the results of treatment with the mentioned preparations. Their effects were most pronounced in the fruits of medium ripeness. 2-CEPA and ethacide increased the ethylene evolution in banana fruits on the average by 25-30%. AOA treatment decreased the ethylene evolution in these fruits by 30%. The PIPG content in fruit pulp was insignificant; 2-CEPA almost did not change its content in banana skin, while ethacide and AOA somewhat decreased it. Consequently, the regulators of ethylene biosynthesis have a potential for optimizing the state of banana fruits during storage and sale.

Differential transcriptional regulation of banana sucrose phosphate synthase gene in response to ethylene, auxin, wounding, low temperature and different photoperiods during fruit ripening and functional analysis of banana SPS gene promoter.

Sucrose phosphate synthase (SPS) (EC 2.3.1.14) is the key regulatory component in sucrose formation in banana (Musa acuminata subgroup Cavendish, cv Giant governor) fruit during ripening. This report illustrates differential transcriptional responses of banana SPS gene following ethylene, auxin, wounding, low temperature and different photoperiods during ripening in banana fruit. Whereas ethylene strongly stimulated SPS transcript accumulation, auxin and cold treatment only marginally increased the abundance of SPS mRNA level, while wounding negatively regulated SPS gene expression. Conversely, SPS transcript level was distinctly increased by constant exposure to white light. Protein level, enzymatic activity of SPS and sucrose synthesis were substantially increased by ethylene and increased exposure to white light conditions as compared to other treatments. To further study the transcriptional regulation of SPS in banana fruit, the promoter region of SPS gene was cloned and some cis-acting regulatory elements such as a reverse GCC-box ERE, two ARE motifs (TGTCTC), one LTRE (CCGAA), a GAGA-box (GAGA...) and a GATA-box LRE (GATAAG) were identified along with the TATA and CAAT-box. DNA-protein interaction studies using these cis-elements indicated a highly specific cis-trans interaction in the banana nuclear extract. Furthermore, we specifically studied the light responsive characteristics of GATA-box containing synthetic as well as native banana SPS promoter. Transient expression assays using banana SPS promoter have also indicated the functional importance of the SPS promoter in regulating gene expression. Together, these results provide insights into the transcriptional regulation of banana SPS gene in response to phytohormones and other environmental factors during fruit ripening.