Pisang Awak Research Articles

A Novel Banana Mutant "RF 1" (Musa spp. ABB, Pisang Awak Subgroup) for Improved Agronomic Traits and Enhanced Cold Tolerance and Disease Resistance.

Banana is a major fruit crop grown in tropical and subtropical regions worldwide. Among cultivars, “FenJiao, FJ” (Musa spp. ABB, Pisang Awak subgroup) is a popular variety of bananas, due to its better sugar-acid blend and relatively small fruit shape. However, because the traditional FJ variety grows relatively high in height, it is vulnerable to lodging and unsuitable for harvesting. In this study, we sought desirable banana mutants by carrying out ethyl methanesulfonate (EMS) mutagenesis with the FJ cultivar. After the FJ shoot tips had been treated with 0.8% (v/v) EMS for 4 h, we obtained a stably inherited mutant, here called “ReFen 1” (RF1), and also observed a semi-dwarfing phenotype. Compared with the wild type (FJ), this RF1 mutant featured consistently improved agronomic traits during 5-year field experiments conducted in three distinct locations in China. Notably, the RF1 plants showed significantly enhanced cold tolerance and Sigatoka disease resistance, mainly due to a substantially increased soluble content of sugar and greater starch accumulation along with reduced cellulose deposition. Therefore, this study not only demonstrated how a powerful genetic strategy can be used in fruit crop breeding but also provided insight into the identification of novel genes for agronomic trait improvement in bananas and beyond.

Development of direct regeneration protocol for mass multiplication of Musa spp. variety Udhayam (Pisang Awak, ABB) using different explants

Musa spp. variety Udhayam (Pisang Awak, ABB) is the first high yielding selection from ICAR-NRCB, Trichy released during 2005. The demand for quality planting material shows an increasing trend because of its higher yield (40%) than the local Karpuravalli. But this variety is highly recalcitrant for shoot tip culture owing to its high phenolic exudation, and very low shoot proliferation rate (<2.0). Therefore, in the present study, attempts were made to develop direct regeneration protocol for the aforementioned variety using various explants like cormlets and male floral hands other than shoot tips. Results revealed that the direct regeneration protocols using cormlets and male floral hands were totally free from latent contamination and recorded high rate of shoot multiplication as against shoot tip explants. Among the three explants used, immature male floral hands showed not only higher multiplication rate under in vitro conditions and also performed better under field conditions compared to shoot tip and cormlet derived plants. The plantlets derived from different explants were found to be true to type as confirmed using ISSR markers. Field performance of the plants derived from various explants indicated that though all are suitable for direct regeneration, male floral hands was superior followed by sucker, shoot tip and cormlets in terms of bunch yield and crop duration. Key message: Immature male flower buds are the best explants for mass multiplication through direct regeneration and commercial exploitation in banana variety Udhayam (Pisang Awak, ABB).

Hybrid infrared with hot air drying of Pisang‐Awak banana: Kinetics and shrinkage quality

AbstractThe purpose of this study was to develop the prototype drying system for drying the Pisang‐Awak (PA) banana. It was designed and implemented to study the drying kinetics in each drying mode: hot air drying (HA), infrared drying (IR), and hybrid drying (Hy). The experimental results were fit with simulation results from the finite element method (FEM). Two statistical parameters, the coefficient of determination and the root mean square error , were used to assess the fit between experimental results and simulation results, and their respective ranges were 0.960–0.997 and 0.014–0.050. For PA banana drying the most suitable drying mode is hybrid, combining 1.5 m/s flow of hot air and IR heating at 60°C drying temperature. The axial and radial shrinkages of PA banana were the largest in Hy mode at 60°C, namely 18.2 and 27.3%, respectively, and this choice gave the best/lowest specific energy consumption (SEC) for drying performance and the best final dried PA banana.Practical ApplicationsThe understanding of the drying kinetics and shrinkage properties of the dried PA banana is important for the choice of drying process because these reflect the quality of the dried product and help an engineer to design the drying system. Therefore, the empirical mathematical modeling of the drying process serves a crucial role in the food industry sector. These results can be used to quantify temperature and moisture content as functions of drying time to monitor the drying process of PA banana, saving energy and time.

Diverse Banana Pseudostems and Rachis Are Distinctive for Edible Carbohydrates and Lignocellulose Saccharification towards High Bioethanol Production under Chemical and Liquid Hot Water Pretreatments

Banana is a major fruit crop throughout the world with abundant lignocellulose in the pseudostem and rachis residues for biofuel production. In this study, we collected a total of 11 pseudostems and rachis samples that were originally derived from different genetic types and ecological locations of banana crops and then examined largely varied edible carbohydrates (soluble sugars, starch) and lignocellulose compositions. By performing chemical (H2SO4, NaOH) and liquid hot water (LHW) pretreatments, we also found a remarkable variation in biomass enzymatic saccharification and bioethanol production among all banana samples examined. Consequently, this study identified a desirable banana (Refen1, subgroup Pisang Awak) crop containing large amounts of edible carbohydrates and completely digestible lignocellulose, which could be combined to achieve the highest bioethanol yields of 31–38% (% dry matter), compared with previously reported ones in other bioenergy crops. Chemical analysis further indicated that the cellulose CrI and lignin G-monomer should be two major recalcitrant factors affecting biomass enzymatic saccharification in banana pseudostems and rachis. Therefore, this study not only examined rich edible carbohydrates for food in the banana pseudostems but also detected digestible lignocellulose for bioethanol production in rachis tissue, providing a strategy applicable for genetic breeding and biomass processing in banana crops.

Functional, Physicochemical, and Antioxidant Properties of Flour and Cookies from Two Different Banana Varieties (Musa acuminata cv. Pisang awak and Musa acuminata cv. Red dacca).

Banana (Musa acuminata) is grown abundantly in tropical and subtropical countries, and it is consumed as raw or processed. Banana is a significant source of nutrients, and it has been found to contain carbohydrates and other nutritional components. The present study was conducted to evaluate the proximate composition, antioxidant composition, and physicochemical properties of flour obtained from two different banana varieties (Musa acuminata cv. Pisang awak and Musa acuminata cv. Red dacca) and to evaluate the proximate composition and antioxidant composition of cookies prepared by incorporating both banana flours. Several sets of cookie samples were prepared separately by incorporating each banana flour where wheat flour and banana flour combinations were 85%-15%, 75%-25%, 70%-30%, and 0-100%. These samples were evaluated for sensory attributes, and two best cookie formulations were selected (70% wheat flour and 30% banana flour) for the analysis. Both Awak and Dacca had obtained similar amount of carbohydrates p < 0.05 while Dacca had recorded a higher amount of moisture, fat, protein, ash, and phytonutrients such as polyphenols, antioxidants, and flavonoids. Dacca flour had obtained higher values for physicochemical properties like water holding capacity (WHC) and oil holding capacity (OHC). L∗, a∗, and b∗ values were evaluated for banana flour incorporated cookies. Lightness and the redness of cookies were prominent while yellowness was not prominent. There was no significant difference in texture parameters but hardness was higher in banana cookies as they contained a higher content of protein and fiber.

Transcriptome and metabolome profiling provide insights into molecular mechanism of pseudostem elongation in banana

BackgroundBanana plant height is an important trait for horticultural practices and semi-dwarf cultivars show better resistance to damages by wind and rain. However, the molecular mechanisms controlling the pseudostem height remain poorly understood. Herein, we studied the molecular changes in the pseudostem of a semi-dwarf banana mutant Aifen No. 1 (Musa spp. Pisang Awak sub-group ABB) as compared to its wild-type dwarf cultivar using a combined transcriptome and metabolome approach.ResultsA total of 127 differentially expressed genes and 48 differentially accumulated metabolites were detected between the mutant and its wild type. Metabolites belonging to amino acid and its derivatives, flavonoids, lignans, coumarins, organic acids, and phenolic acids were up-regulated in the mutant. The transcriptome analysis showed the differential regulation of genes related to the gibberellin pathway, auxin transport, cell elongation, and cell wall modification. Based on the regulation of gibberellin and associated pathway-related genes, we discussed the involvement of gibberellins in pseudostem elongation in the mutant banana. Genes and metabolites associated with cell wall were explored and their involvement in cell extension is discussed.ConclusionsThe results suggest that gibberellins and associated pathways are possibly developing the observed semi-dwarf pseudostem phenotype together with cell elongation and cell wall modification. The findings increase the understanding of the mechanisms underlying banana stem height and provide new clues for further dissection of specific gene functions.

Exogenous Polyazole (PP&lt;sub&gt;333&lt;/sub&gt;) Regulated Flower Physiology to Promote Early Bud Extraction of Pisang Awak (ABB)

In this study, the first and second harvesting Pisang Awak in the field were sprayed with different dosage of paclobutrazol in order to analyze the mechanism of its induction of flowering. The results showed that there was no significant difference in the total number of newly extracted leaves between treatments. The first harvesting was 3.0 g/plant, and the second one was 2.0 g/plant. The pumping speed of leaves is the fastest and the accumulation of leaves number is the earliest. The 3.0 g/plant treatment of first harvesting Pisang Awak had the earliest bud extraction stage, and the bud extraction rate reached 62.5% at 170 days after treatment, about 40 days earlier than control group. Within the range of 1.0~5.0 g/plant, PP 333 &nbsp;promoted carbohydrate synthesis in leaves of Pisang Awak, significantly reduced the accumulation of nitrogen, significantly increased the carbon-nitrogen ratio (C/N), and significantly reduced the contents of GA 3 &nbsp;and IAA in the leaves. The results showed that the exogenous polyazole could accelerate the pumping speed of leaves, promote flowering and early bud extraction by regulating the distribution of carbon and nitrogen nutrients and the content of endogenous hormones, thus providing technical guidance for the management of early bud extraction culture of&nbsp;Pisang Awak.

ผลของการใช้ผงสีจาก Monascus purpureus หมักกับกล้วยน้ำว้าทดแทนไนไตรท์ในผลิตภัณฑ์แหนม

ผลของการใช้ผงสีจาก Monascus purpureus หมักกับกล้วยน้ำว้าทดแทนไนไตรท์ในผลิตภัณฑ์แหนม

The development of a multiplex PCR assay for the detection of Fusarium oxysporum f. sp. cubense lineage VI strains in East and Central Africa

Banana is a staple food and cash crop grown in East and Central Africa (ECA). The main banana varieties grown in ECA are the East African highland bananas (EAHB), although dessert/beer bananas such as Sukari Ndizi, Kayinja (Pisang Awak) and Gros Michel are also produced due to their high value at local markets. The Fusarium wilt fungus Fusarium oxysporum f. sp. cubense (Foc) causes disease of susceptible dessert/beer bananas, which significantly reduces yields. Banana Fusarium wilt is managed by excluding the pathogen from disease-free areas and by planting disease-resistant varieties in infested fields. Six phylogenetically closely-related vegetative compatibility groups (VCGs) of Foc, VCGs 0124, 0125, 0128, 01212, 01220 and 01222 are present in ECA, which all group together in Foc Lineage VI. Rapid and accurate detection of Foc Lineage VI strains is thus important to prevent its spread to disease-free areas. In this study, molecular markers specific to Foc Lineage VI were therefore developed. Primer sets were then combined in a multiplex PCR assay, and validated on a worldwide population of 623 known Foc isolates, other formae speciales and non-pathogenic Fusarium oxysporum isolates. The Foc Lineage VI multiplex PCR was used to identify Foc isolates collected in banana fields at five locations in Uganda and Tanzania. Foc Lineage VI DNA was detected at a concentration as low as 0.1 ng/μl, both in the absence and presence of banana DNA, and can therefore be used as an accurate diagnostic tool for Foc Lineage VI strains.

Predicting Virulence of Fusarium Oxysporum f. sp. Cubense Based on the Production of Mycotoxin Using a Linear Regression Model.

Fusarium wilt caused by Fusarium oxysporum f.sp. cubense (Foc) is one of the most destructive diseases for banana. For their risk assessment and hazard characterization, it is vital to quickly determine the virulence of Foc isolates. However, this usually takes weeks or months using banana plant assays, which demands a better approach to speed up the process with reliable results. Foc produces various mycotoxins, such as fusaric acid (FSA), beauvericin (BEA), and enniatins (ENs) to facilitate their infection. In this study, we developed a linear regression model to predict Foc virulence using the production levels of the three mycotoxins. We collected data of 40 Foc isolates from 20 vegetative compatibility groups (VCGs), including their mycotoxin profiles (LC-MS) and their plant disease index (PDI) values on Pisang Awak plantlets in greenhouse. A linear regression model was trained from the collected data using FSA, BEA and ENs as predictor variables and PDI values as the response variable. Linearity test statistics showed this model meets all linearity assumptions. We used all data to predict PDI with high fitness of the model (coefficient of determination (R2 = 0.906) and adjust coefficient (R2adj = 0.898)) indicating a strong predictive power of the model. In summary, we developed a linear regression model useful for the prediction of Foc virulence on banana plants from the quantification of mycotoxins in Foc strains, which will facilitate quick determination of virulence in newly isolated Foc emerging Fusarium wilt of banana epidemics threatening banana plantations worldwide.

Unravelling the complex story of intergenomic recombination in ABB allotriploid bananas.

Background and AimsBananas (Musa spp.) are a major staple food for hundreds of millions of people in developing countries. The cultivated varieties are seedless and parthenocarpic clones of which the ancestral origin remains to be clarified. The most important cultivars are triploids with an AAA, AAB or ABB genome constitution, with A and B genomes provided by M. acuminata and M. balbisiana, respectively. Previous studies suggested that inter-genome recombinations were relatively common in banana cultivars and that triploids were more likely to have passed through an intermediate hybrid. In this study, we investigated the chromosome structure within the ABB group, composed of starchy cooking bananas that play an important role in food security.MethodsUsing SNP markers called from RADSeq data, we studied the chromosome structure of 36 ABB genotypes spanning defined taxonomic subgroups. To complement our understanding, we searched for similar events within nine AB hybrid genotypes.Key ResultsRecurrent homologous exchanges (HEs), i.e. chromatin exchanges between A and B subgenomes, were unravelled with at least nine founding events (HE patterns) at the origin of ABB bananas prior to clonal diversification. Two independent founding events were found for Pisang Awak genotypes. Two HE patterns, corresponding to genotypes Pelipita and Klue Teparod, show an over-representation of B genome contribution. Three HE patterns mainly found in Indian accessions shared some recombined regions and two additional patterns did not correspond to any known subgroups.ConclusionsThe discovery of the nine founding events allowed an investigation of the possible routes that led to the creation of the different subgroups, which resulted in new hypotheses. Based on our observations, we suggest different routes that gave rise to the current diversity in the ABB cultivars, routes involving primary AB hybrids, routes leading to shared HEs and routes leading to a B excess ratio. Genetic fluxes took place between M. acuminata and M. balbisiana, particularly in India, where these unbalanced AB hybrids and ABB allotriploids originated, and where cultivated M. balbisiana are abundant. The result of this study clarifies the classification of ABB cultivars, possibly leading to the revision of the classification of this subgroup.

Study of prebiotic properties of selected banana species in Thailand.

Prebiotics are functional foods with health-promoting properties that are used in many developed countries. Thailand is one of the countries that produces many plants that should have prebiotic properties. In this study, we investigated the potential prebiotic effects of powders obtained from Saba, Pisang Awak Banana and Silver bluggoe in vitro in accordance with their physical, chemical and microbiological properties. These selected plants were found to demonstrate good water-/oil-binding properties. They contained chlorophyll, beta carotene and lycopene and showed good resistance to stomach and small-intestine enzymes. The selected plants were further used to evaluate prebiotic properties by supplementing as a carbon source in culturing broth for growing probiotic bacteria and pathogenetic bacteria. The increase in the number of probiotic bacteria during fermentation of these selected plants correlated with decreased pH. The growth of four strains of probiotic bacteria seemed to be promoted in MRS broth containing these selected plants, but no significant differences in the number of probiotic bacterial groups were detected in response to difference concentrations of all these selected plants. In addition, we noted that a decrease in the number of all four strains of pathogenic bacteria during fermentation of these selected plants correlated with a decreased pH. Moreover, the antimicrobial activity of selected plant prebiotics supported probiotic substance production to inhibit growth of pathogenic bacteria. In conclusion, we have shown that the addition of selected prebiotic plants, indicating that they should be used as a prebiotic food ingredient, represents a potential alternative to available commercial prebiotics.

Identification of Banana corm weevil Cosmopolites sordidus germar resistance in Musa germplasm

In the present study, a field and in vitro screening approaches were followed to identify the resistant Musa accessions (n=310) against banana corm weevil Cosmopolites sordidus (Germar). The corm was crosssectioned and the tunnels (galleries) made by the grub were recorded. Based on the ratio of galleries, the % was calculated. The infestation level was categorized into resistant, less, moderate and highly susceptible. The results revealed three resistant accessions viz., Kanthali (ABB- Pisang awak), Sambalneyvannan (ABB- Pisang awak) and Bhimkol (BB- wild balbisiana). Around 44 accessions (AA:2, AAA:5, AAB:9, AB:4; BB:5; ABB:15, ABBB:2; Rhodochlayms:2) from different genomes were identified as less susceptible.

Determination of nucleation assay for anti-urolithiasis activity from bagasse Musa acuminate x balbisiana Colla cv. Pisang Awak Legor methanolic extracts using uv-spectrometer and size measurement.

Determination of inhibition of calcium oxalate (CaOx) crystallisation in vitro by nucleation assay is based on the rates of nucleation by comparing the slope of the turbidity of a control system with that of one exposed to the extract, which was found to be inaccurate when the CaOx crystals were formed and precipitated. A need exists for improved methods to determine the inhibition activity in nucleation assay for the study of anti-urolithiasis activity. In this study, the size reduction of CaOx crystals after treated with methanolic extract of Musa acuminate x balbisiana Colla cv. Pisang Awak Legor bagasse was measured under light microscopy and correlated to the turbidity and percentage of inhibition. Different concentrations of bagasse extract (2, 10, 30, 50 and 100 mg/ml) were investigated and the result shows that high concentration of extract would promote reduction in CaOx’s stone size, but it increased the amount of sediment crystals, resulting high turbidity. The stone size was reduced up to 93.76±0.19% in the presence of 100 mg/mL extract while the inhibition percentage was negative (-102.17±0.04%) as the optical density (OD) of the extract was higher than control in the turbidity calculation. The results of this study are expected to provide an understanding on the way of calculating the activity in nucleation assay.

Physiological and transcriptomic analysis reveals the roles of 1-MCP in the ripening and fruit aroma quality of banana fruit (Fenjiao).

Fenjiao (Musa ABB Pisang Awak) is a popular banana cultivar due to its good taste and stress resistance, but it has a short shelf-life and deteriorates rapidly post-harvest. The effects of 1-methylcyclopropene (1-MCP) treatment on fruit physiology and quality and transcriptomic profiles are investigated in this study. The results showed that 1-MCP significantly delayed fruit ripening by repressing fruit softening and inhibiting the respiratory rate and ethylene production. The 1-MCP treatment delayed sugar accumulation and influenced the content of the precursors of the biosynthesis of aroma volatiles. 1-MCP reduced the production of flavor-contributing volatile esters isoamyl isobutyrate, isoamyl acetate and trans-2-hexenal and hexanal, but dramatically increased the hexyl acetate production at the full-ripening stage. The transcriptomic analysis showed that 1-MCP dramatically affected the transcript profiles during fruit ripening, especially the KEGG pathways involved in amino acid metabolism, biosynthesis of other secondary metabolites, carbohydrate metabolism, lipid metabolism, signal transduction, and translation classes. The key genes and the corresponding enzyme activities involved in the volatile and ethylene synthesis were severely repressed due to the 1-MCP treatment. The 1-MCP treatment effectively delayed Fenjiao fruit ripening, but affected volatile production by reducing the precursor production and expression level of genes involved in the metabolism pathways of ethylene, auxin and volatiles.

The Epidemiology of Fusarium Wilt of Banana.

Fusarium wilt of banana (also known as Panama disease) has been a problem in Australia since 1874. Race 1 of the pathogen (Fusarium oxysporum f. sp. cubense) is responsible for damage to ‘Lady Finger’ (AAB, Pome subgroup) and other less widely grown cultivars such as ‘Ducasse’ (Pisang Awak, ABB). Subtropical Race 4 (STR4) also affects these cultivars as well as Cavendish cultivars (AAA) in southern Queensland and northern New South Wales where cold temperature predisposition is involved. Tropical Race 4 (TR4) has led to the demise of the Cavendish industry in the Northern Territory, and its presence was confirmed in a North Queensland plantation in 2015, which warranted destruction of all banana plants on the property; as of this writing (April 2019), TR4 has spread to two adjacent properties. This review, which was commissioned by Biosecurity Queensland in response to the 2015 TR4 outbreak, considers the key epidemiological factors associated with the onset of a Fusarium wilt epidemic. Resistance to TR4, which is mediated by events following entry by the pathogen into the xylem, is not present in any commercially acceptable banana cultivar. Also, there is no effective chemical agent that can be used to manage the disease. Besides prevention, very early recognition and rapid containment of a disease outbreak are necessary to prevent epidemic development. A good understanding of the key factors responsible for disease development is required when devising practical protocols for the destruction of infected plants, treatment of surrounding infested soil, and reduction of inoculum in plant residues and soil.

First Report of Banana Streak Virus Infecting Bananas (Musa spp.) in Georgia, U.S.A.

Banana streak virus (BSV) is a badnavirus containing a circular dsDNA genome of 7.4 kb that causes a viral leaf streak disease of banana (Musa spp.) worldwide (Dallot et al. 2001). On bananas, typical symptoms of BSV include broken or continuous chlorotic streaks or spindle-shaped patterns that are first chlorotic, become increasingly dark in color, and subsequently result in black streaking in older leaves (Dallot et al. 2001). In the summer of 2019, six symptomatic leaves from three different plants were collected from the University of Georgia Banana Research Plot, Tifton, GA. The cultivar is ‘Pisang Awak’, and it belongs to the tetraploid AABB genome group. Initial identification was performed by assessing disease symptoms including chlorotic streaks on leaves that became brown and black chlorotic streaks later, resembling those of banana streak disease (Lockhart 1986). BSV was verified via molecular and serological tests. Genomic DNA from leaf tissue of three different symptomatic plants and two healthy plants was extracted using a DNeasy Plant Mini Kit (Qiagen, Valencia, CA). Samples were tested for the presence of BSV by two separate PCR amplification methods. One was targeting the aspartic protease (AP) and reverse transcription (RT) regions of ORF3 using primer pair BSV 4673 (5′-GGAATGAAAGAGCAGGCC-3′) and BSV 5317 (5′-AGTCATTGGGTYCAACCTCTGTCCC-3′) with an amplicon size of 644 bp (Manoranjitham et al. 2012). Another PCR analysis was targeting the coat protein (CP) region of ORF3 with primer pair BSV 156 (5′-TTACCTCCAGCACAAAGTCG-3′) and BSV 962 (5′-TTCTCCACAGGCATAACACC-3′) designed in this study with a product size of 806 bp. Both PCR reactions for all six symptomatic samples produced the expected sizes of the fragments for BSV; however, two samples from the healthy plants did not produce any bands. The amplified products were then sequenced and subjected to BLAST analysis for further identification. Sequence analysis revealed that the obtained partial sequence of the AP and RT region (MN567071) shared 100% identity to corresponding sequences from BSV OL virus isolate BSOLV-IN2 (accession no. JQ409540). Furthermore, the obtained CP gene sequence (MN567072) also showed 100% identity with BSV isolate BSOLV-IN2. Samples were also tested for the presence of BSV by real-time PCR with primers BSV 1075 (5′-CACATTGACGGAAAGGACAACG-3′) and BSV 1198 (5′-TGTGAAATACCTCCTCCACTGC-3′) targeting the RNase H gene (Delanoy et al. 2003), and the results confirmed its identity as BSV. In addition to the molecular tests, a DAS-ELISA test was carried out on the remaining symptomatic leaf tissues for further confirmation of BSV according to the manufacturer’s protocol (Nano Diagnostics, Fayetteville, AR). All three samples tested by ELISA were positive for BSV. To the best of our knowledge, this is the first report of BSV infecting Musa spp. in Georgia. This virus could pose an imminent threat to the newly growing banana industry in this area if it spread in banana fields under conditions in Georgia. Our findings will be helpful for banana growers in Georgia by taking appropriate control strategies to combat this viral disease. Further research is needed to elucidate epidemiology, symptomatology, vector transmission, and crop losses due to BSV in Georgia and the United States.

The Involvement of the Banana F-Box Protein MaEBF1 in Regulating Chilling-Inhibited Starch Degradation through Interaction with a MaNAC67-Like Protein.

Low-temperature storage is a common strategy for preserving and transporting vegetables and fruits. However, many fruits are hypersensitive to chilling injury, including bananas. In the present study, storage conditions of 11 °C delayed the ripening of Fenjiao (Musa ABB Pisang Awak) banana, and the pulp could be softened after ethephon treatment. Storage conditions of 7 °C prevented fruit from fully softening, and fruit contained a significantly higher starch content and lower soluble sugar content. MaEBF1, a critical gene component in the ethylene signaling pathway, was repressed during ripening after fruit had been stored for 12 days at 7 °C. The expression of a series of starch degradation-related genes and a MaNAC67-like gene were also severely repressed. Both MaEBF1 and MaNAC67-like genes were ethylene-inducible and localized in the nucleus. MaNAC67-like protein was able to physically bind to the promoter of genes associated with starch degradation, including MaBAM6, MaSEX4, and MaMEX1. Yeast two-hybrid, GST-pull down, and BiFC assays showed that MaEBF1 interacted with the MaNAC67-like protein, and their interaction further activated the promoters of MaBAM6 and MaSEX4. The current study indicates that MaNAC67-like is a direct regulator of starch degradation and potential for involvement in regulating chilling-inhibited starch degradation by interacting with the ethylene signaling components in banana fruit. The present work paves the way for further functional analysis of MaEBF1 and MaNAC67-like in banana, which will be useful for understanding the regulation of banana starch metabolism and fruit ripening.

Imbalanced expression of stay-green 1 alleles in banana AAB/ABB cultivars prevents high-temperature-induced green ripening as in AAA Cavendish fruit

Cavendish banana (Musa AAA) shows green-ripening at high temperatures above 24 °C, while Bluggoe fruit (Musa ABB) turns completely yellow. To understand the genomic constitution of the fruit de-greening trait, we compared fruit ripening and chlorophyll (Chl) degradation in 4 banana cultivars, belonging to the Cavendish (AAA), Mysore (AAB), Pisang Awak (ABB) and Bluggoe (ABB) subgroups, at 30 °C and 20 °C. Compared with fruit at 20 °C, ripening progress of the 4 cultivars at 30 °C, as represented by the change in fruit firmness and expression of fruit ripening-related genes, ACS ACO and PG, was accelerated, while the de-greening of fruits was repressed in the AAA cultivar but enhanced in the 3 hybrids (AAB/ABB). The expression of Stay-Green 1 (SGR1), a key Chl degradation gene, was reduced in the AAA cultivar but induced in the hybrids, correlating to the fruit de-greening patterns. The A- and B-SGR1 alleles, from the A- and B-genome, respectively, and a recombinant of the two alleles (H-SGR1) were identified in the AAB/ABB cultivars. A highly conserved polymorphism code was found to differentiate the A/B/H-SGR1 alleles. Allele-specific expression analysis showed that the Bluggoe fruit transcribed only B-SGR1, while Pisang Awak and Mysore expressed B/H- and A/B-SGR1, respectively, and higher B-SGR1 transcription levels were detected at 30 °C than at 20 °C. Transient expression of A/B/H-SGR1 in tobacco leaves demonstrated that SGR1s were all targeted to chloroplasts, and A-SGR1 showed a weaker Chl degradation capacity than B/H-SGR1. The allelic imbalanced expression (AIE) of SGR1 was demonstrated to confer the different fruit de-greening traits to the AAA and AAB/ABB cultivars at high temperatures.

Banana peduncle – A green and renewable heterogeneous base catalyst for biodiesel production from Ceiba pentandra oil

In the present study, the feasibility of utilizing Musa spp “Pisang Awak” peduncle derived ash as a highly effective renewable heterogeneous basic catalyst for transesterification of underutilized non-edible Ceiba pentandra oil (CPO) was investigated. The physiochemical characteristics of the calcined banana peduncle (CBP) were studied by Fourier Transform Infrared Spectroscopy (FTIR), X-ray diffraction (XRD), Scanning Electron Microscopy and Energy Dispersive Atomic X-ray spectroscopy (SEM-EDAX). Biodiesel was produced by a two-step esterification-transesterification process. In the first step, FFA content of the oil was reduced from 7% to 1.6% using reaction conditions of 1.0 vol% H2SO4 concentration, 1h reaction time, 1:4 v/v methanol to oil volumetric ratio with constant reaction temperature of 60 °C. In the second step, response surface methodology (RSM) using central composite design (CCD) was employed to determine the optimal process conditions of transesterification process variables. Based on the RSM results, the optimum process conditions for transesterification of CPO into fatty acid methyl ester (FAME) was found to be 1.978 wt% catalyst concentration, 60 min reaction time, 9.20:1 methanol to oil molar ratio with a maximum predicted FAME yield of 99.36% which was evaluated experimentally as 98.69 ± 0.18%.