Metabolome Analysis of Banana (Musa acuminata) Treated With Chitosan Coating and Low Temperature Reveals Different Mechanisms Modulating Delayed Ripening

Banana (Musa acuminata) is one of the most important crop plants consumed in many countries. However, the commercial value decreases during storage and transportation. To maintain fruit quality, postharvest technologies have been developed. Storage at low temperature is a common method to prolong the shelf life of food products, especially during transportation and distribution. Another emerging approach is the use of chitosan biopolymer as an edible coating, which can extend the shelf life of fruit by preventing moisture and aroma loss, and inhibiting oxygen penetration into the plant tissue. Gas chromatography-mass spectrometry metabolite profiling of the banana ripening process was performed to clarify the global metabolism changes in banana after chitosan coating or storage at low temperature. Both postharvest treatments were effective in delaying banana ripening. Interestingly, principal component analysis and orthogonal projection to latent structure regression analysis revealed significant differences of both treatments in the metabolite changes, indicating that the mechanism of prolonging the banana shelf life may be different. Chitosan (1.25% w/v) treatment stored for 11 days resulted in a distinct accumulation of 1-aminocyclopropane-1-carboxylic acid metabolite, an important precursor of ethylene that is responsible for the climacteric fruit ripening process. Low temperature (LT, 14 ± 1°C) treatment stored for 9 days resulted in higher levels of putrescine, a polyamine that responds to plant stress, at the end of ripening days. The findings clarify how chitosan delays fruit ripening and provides a deeper understanding of how storage at low temperature affects banana metabolism. The results may aid in more effective development of banana postharvest strategies.

Banana Flower-Insect Interaction: Alpha-Pinene as Potential Attractant for the Insect Vector of Banana Blood Disease

Volatile metabolites are produced by plants for self-defense and as communication mediators with the environment. Terpenes are volatiles emitted as odorant cues for herbivores and microorganisms. This study was aimed to investigate volatile metabolites produced by banana flowers that attract insect vectors of BBD. The volatile metabolites from banana flowers were extracted by headspace-solid phase microextraction (HS-SPME) and identified by gas chromatography–mass spectrometry (GC-MS). It was apparent that the concentrations of the metabolite alpha-pinene gradually increased from the first to the the third stage. Comparison of metabolites produced by symptomatic banana male flowers for BBD infection with non-symptomatic ones showed that the concentration of alpha-pinene was higher in symptomatic male flowers. In addition, preference for alpha-pinene was tested on three insect vector species (Rhodesiella bhutanensis, Drosophila sp., and Musca sp.), analyzed by M. Anova p<0.001, F(1.5) =12.539 and Duncan test. Results showed that the insect vectors were mostly attracted to 20 µl volume of alpha-pinene compared to the other volumes and that alpha-pinene functioned as an attractant to these insects. This research is important for the formulation of attractants for insect vectors of BBD to control transmission of banana blood disease.

Identification of Banana Plants from Unmanned Aerial Vehicles (UAV) Photos Using Object Based Image Analysis (OBIA) Method (A Case Study in Sayang Village, Jatinangor District, West Java)

  Banana is one of the leading fruit commodities of Indonesia and ranks the sixth position as one of the largest banana producers in the world. There are more than 200 types of banana in Indonesia. The utilization of bananas is influenced by the local culture, where in every 10 horticultural households, 5 of them plant bananas both as garden plants or field plants. This horticultural crop is expectantly being one of the actions to improve economic prosperity especially in rural areas. In maintaining the diversity of the growing bananas in rural areas, a geospatial approach to identify the vegetation is required. Remote sensing technology is one of the solutions to observe and to develop banana plants with one of the methods namely Object Based Image Analysis (OBIA). This method consists of segmentation, classification, and validation. In classification process, the OBIA method distinguishes objects not only based on pixel values but also on the basis of the shape, area, and texture around them. This research has proven that the classification using OBIA method is better than the traditional classification such as maximum likelihood classification method to identify banana plants. OBIA method can quickly identifies the vegetation and non-vegetation, also the regular plants and banana plants.

A metabolomics-based approach for the evaluation of off-tree ripening conditions and different postharvest treatments in mangosteen (Garcinia mangostana)

INTRODUCTION

Metabolomics is an important tool to support postharvest fruit development and ripening studies. Mangosteen (Garcinia mangostana L.) is a tropical fruit with high market value but has short shelf-life during postharvest handling. Several postharvest technologies have been applied to maintain mangosteen fruit quality during storage. However, there is no study to evaluate the metabolite changes that occur in different harvesting and ripening condition. Additionally, the effect of postharvest treatment using a metabolomics approach has never been studied in mangosteen.

OBJECTIVES

The aims of this study were to evaluate the metabolic changes between different harvesting and ripening condition and to evaluate the effect of postharvest treatment in mangosteen.

METHODS

Mangosteen ripening stage were collected with several different conditions ("natural on-tree", "random on-tree" and "off-tree"). The metabolite changes were investigated for each ripening condition. Additionally, mangosteen fruit was harvested in stage 2 and was treated with several different treatments (storage at low temperature (LT; 12.3 ± 1.4 °C) and stress inducer treatment (methyl jasmonate and salicylic acid) in comparison with control treatment (normal temperature storage) and the metabolite changes were monitored over the course of 10 days after treatment. The metabolome data obtained from gas chromatography coupled with mass spectrometry were analyzed by multivariate analysis, including hierarchical clustering analysis, principal component analysis, and partial to latent squares analysis.

RESULTS

"On-tree" ripening condition showed the progression of ripening process in accordance with the accumulation of some aroma precursor metabolites in the flesh part and pectin breakdown in the peel part. Interestingly, similar trend was found in the "off-tree" ripening condition although the progression of ripening process observed through color changes occurred much faster compared to "on-tree" ripening. Additionally, low-temperature treatment is shown as the most effective treatment to prolong mangosteen shelf-life among all postharvest treatments tested in this study compared to control treatment. After postharvest treatment, a total of 71 and 65 metabolites were annotated in peel and flesh part of mangosteen, respectively. Several contributed metabolites (xylose, galactose, galacturonic acid, glucuronate, glycine, and rhamnose) were decreased after treatment in the peel part. However, low-temperature treatment did not show any significant differences compared to a room temperature treatment in the flesh part.

CONCLUSIONS

Our findings clearly indicate that there is a similar trend of metabolic changes between on-tree and off-tree ripening conditions. Additionally, postharvest treatment directly or indirectly influences many metabolic processes (cell-wall degrading process, sweet-acidic taste quality) during postharvest treatment.

Biodiversity of Bali Banana (Musaceae) and its Usefulness

Banana (Musa spp.) is one the most important agriculture commodities in Indonesia. Archeological and molecular evidences suggest that speciation of this herb occurred in Indonesia, leading to the high diversity in the archipelago. In Bali Island, banana is not only sought for food but as well as for their symbolic role in religious and cultural ceremonies. However, the high demand for bananas in Bali is not yet supported by the adequate production of local farms. This presented study aimed to investigate the diversity of banana cultivars or sub-species in Bali and its usefulness to determine preferable cultivars to cultivate. We recorded and characterized 43 banana cultivars in 10 villages that represent the 8 regencies and 1 city of Bali province. Out of the 43 cultivars, 7 were highly used and at least one cultivar was discovered in each of the studied village.  The presence of these cultivars in the study areas were confirmed by site visit and characterization of the fruits. Among the highly ranked cultivars or species, only biu kayu is unique to Bali as it was not found in the closest provinces of East Java and Madura. Hence, the results suggested that to improve the cultivation and production of these 7 highly used cultivars could be an appropriate solution to meet Bali demand of bananas. Furthermore, cultivating biu kayu would also help conservation effort since this cultivar is also currently listed as a rare genetic resource.

Expression Analysis of 1-aminocyclopropane-1-carboxylic Acid Oxidase Genes in Chitosan-Coated Banana

Banana is a climacteric fruit in which ethylene plays an important role in the regulation of the ripening process. Though it is the most produced fruit in Indonesia, the current post-harvest technologies for exporting this fruit are not economically friendly. Chitosan is one of economical biopolymer for edible coating which can extend fruit shelf-life. However, little study focused on the effect of chitosan coating has been done on gene expression level. In this study, the expression levels of several 1-aminocyclopropan-1-carboxylic acid oxidase (ACO) genes, which is an enzyme to convert 1-aminocyclopropan-1-carboxylic acid to ethylene in banana were analyzed on day 0, 1, 3, 5, 7, and 9 after ethylene treatment. As a result, one gene (ID: Ma01_t11540.1) had a similar expression pattern in both control and chitosan-coated bananas while the other genes (ID: Ma03_t02700.1, Ma05_t09360.1, Ma06_t02600.1, Ma10_t01130.1) showed different expression patterns. Among these genes, two genes (ID: Ma05_t09360.1, Ma10_t01130.1) were expressed higher than the other genes and the peak was observed on day 3. It was indicated that chitosan coating might activate the ethylene biosynthesis pathway in banana while it delayed fruit ripening.

Metabolic profiling of Garcinia mangostana (mangosteen) based on ripening stages

Metabolomics is an emerging research field based on exhaustive metabolite profiling that have been proven useful to facilitate the study of postharvest fruit development and ripening. Specifically, tracking changes to the metabolome as fruit ripens should provide important clues for understanding ripening mechanisms and identify bio-markers to improve post-harvest technology of fruits. This study conducted a time-course metabolome analysis in mangosteen, an economically important tropical fruit valued for its flavor. Mangosteen is a climacteric fruit that requires an important plant hormone ethylene to regulate ripening processes and rate. We first categorized mangosteen samples in different ripening stages based on color changes, an established indicator of ripening. Using gas chromatography/mass spectrometry, small hydrophilic metabolites were profiled from non-ripened to fully ripened (ripening stages 0-6). These metabolites were then correlated with color changes to verify their involvement mangosteen ripening. Our results suggest that the increase of 2-aminoisobutyric acid, psicose, and several amino acids (phenylalanine, valine, isoleucine, serine, and tyrosine) showed a correlation with the progression of mangosteen ripening. This is the first report of the application of non-targeted metabolomics in mangosteen.

The CELLULOSE-SYNTHASE LIKE C (CSLC) family of barley includes members that are integral membrane proteins targeted to the plasma membrane

The CELLULOSE SYNTHASE-LIKE C (CSLC) family is an ancient lineage within the CELLULOSE SYNTHASE/CELLULOSE SYNTHASE-LIKE (CESA/CSL) polysaccharide synthase superfamily that is thought to have arisen before the divergence of mosses and vascular plants. As studies in the flowering plant Arabidopsis have suggested synthesis of the (1,4)-beta-glucan backbone of xyloglucan (XyG), a wall polysaccharide that tethers adjacent cellulose microfibrils to each other, as a probable function for the CSLCs, CSLC function was investigated in barley (Hordeum vulgare L.), a species with low amounts of XyG in its walls. Four barley CSLC genes were identified (designated HvCSLC1-4). Phylogenetic analysis reveals three well supported clades of CSLCs in flowering plants, with barley having representatives in two of these clades. The four barley CSLCs were expressed in various tissues, with in situ PCR detecting transcripts in all cell types of the coleoptile and root, including cells with primary and secondary cell walls. Co-expression analysis showed that HvCSLC3 was coordinately expressed with putative XyG xylosyltransferase genes. Both immuno-EM and membrane fractionation showed that HvCSLC2 was located in the plasma membrane of barley suspension-cultured cells and was not in internal membranes such as endoplasmic reticulum or Golgi apparatus. Based on our current knowledge of the sub-cellular locations of polysaccharide synthesis, we conclude that the CSLC family probably contains more than one type of polysaccharide synthase.