Mature Green Fruit Research Articles

Accumulation of Antioxidative Phenolics and Carotenoids Using Thermal Processing in Different Stages of Momordica charantia Fruit.

The bitter taste of M. charantia fruit limits its consumption, although the health benefits are well known. The thermal drying process is considered as an alternative method to reduce the bitterness. However, processing studies have rarely investigated physiochemical changes in fruit stages. The antioxidant activities and physiochemical properties of various fruit stages were investigated using different thermal treatments. The color of the thermally treated fruit varied depending on the temperature. When heat-treated for 3 days, the samples from the 30 °C and 90 °C treatments turned brown, while the color of the 60 °C sample did not change significantly. The antioxidant activities were increased in the thermally processed samples in a temperature-dependent manner, with an increase in phenolic compounds. In the 90 °C samples, the 2,2-diphenyl-1-picrylhydrazyl radical scavenging activity presented a 6.8-fold higher level than that of nonthermal treatment in mature yellow fruit (S3), whereas the activity showed about a 3.1-fold higher level in immature green (S1) and mature green (S2) fruits. Regardless of the stages, the carotenoid content tended to decrease with increasing temperature. In terms of antioxidant activities, these results suggested that mature yellow fruit is better for consumption using thermal processing.

Chromoplast plastoglobules recruit the carotenoid biosynthetic pathway and contribute to carotenoid accumulation during tomato fruit maturation.

Tomato (Solanum lycopersicum) fruit maturation is associated with a developmental transition from chloroplasts (in mature green fruit) to chromoplasts (in red fruit). The hallmark red color of ripe tomatoes is due to carotenogenesis and accumulation of the red carotenoid lycopene inside chromoplasts. Plastoglobules (PG) are lipid droplets in plastids that are involved in diverse lipid metabolic pathways. In tomato, information on the possible role of PG in carotogenesis and the PG proteome is largely lacking. Here, we outline the role of PG in carotenogenesis giving particular attention to tomato fruit PG proteomes and metabolomes. The proteome analysis revealed the presence of PG-typical FBNs, ABC1K-like kinases, and metabolic enzymes, and those were decreased in the PG of tomato chromoplasts compared to chloroplasts. Notably, the complete β-carotene biosynthesis pathway was recruited to chromoplast PG, and the enzymes PHYTOENE SYNTHASE 1 (PSY-1), PHYTOENE DESATURASE (PDS), ZETA-CAROTENE DESATURASE (ZDS), and CAROTENOID ISOMERASE (CRTISO) were enriched up to twelvefold compared to chloroplast PG. We profiled the carotenoid and prenyl lipid changes in PG during the chloroplast to chromoplast transition and demonstrated large increases of lycopene and β-carotene in chromoplast PG. The PG proteome and metabolome are subject to extensive remodeling resulting in high accumulation of lycopene during the chloroplast-to-chromoplast transition. Overall, the results indicate that PGs contribute to carotenoid accumulation during tomato fruit maturation and suggest that they do so by functioning as a biosynthetic platform for carotenogenesis.

Tomato Cultivar Nyagous Fruit Surface Metabolite Changes during Ripening Affect Salmonella Newport

Tomatoes are a valuable crop consumed year-round. Ripe fruit is picked for local sale, whereas tomatoes intended for transit may be harvested at late mature green or breaker stages when fruit firmness preserves quality. In this study, we evaluated Solanum lycopersicum cv. BHN602 association with three Salmonella serotypes and S. lycopersicum cv. Nyagous with Salmonella Newport using fruit at two ripeness stages. Counts of Salmonella Javiana and Typhimurium were higher from red ripe fruit surfaces of BHN602, and counts of Salmonella Newport were higher from ripe Nyagous fruit than from mature green fruit (P < 0.05). Aqueous fruit washes containing fruit surface compounds collected from ripe Nyagous fruit supported more Salmonella Newport growth than green fruit washes (P < 0.05). Growth curve analysis showed that between 2 and 6 h, Salmonella Newport grew at a rate of 0.25 log CFU/h in red fruit wash compared with 0.17 log CFU/h in green fruit wash (P < 0.05). The parallel trend in Salmonella interaction between fruit and wash suggested that surface metabolite differences between unripe and ripe fruit affect Salmonella dynamics. Untargeted phytochemical profiling of tomato fruit surface washes with gas chromatography time-of-flight mass spectrometry showed that ripe fruit had threefold-lower amino acid and fourfold-higher sugar (fructose, glucose, and xylose) levels than green fruit. Green fruit had higher levels of lauric, palmitic, margaric, and arachidic acids, whereas red fruit had more capric acid. The phenolics ferulic, chlorogenic, and vanillic acid, as well as tyrosol, also decreased with ripening. Although limitations of this study preclude conclusions on how specific compounds affect Salmonella, our study highlights the complexity of the plant niche for foodborne pathogens and the importance of understanding the metabolite landscape Salmonella encounters on fresh produce. Fruit surface phytochemical profiling generated testable hypotheses for future studies exploring the differential Salmonella interactions with tomato varieties and fruit at various ripeness stages.

Genes, Structural, and Biochemical Characterization of Four Chlorophyllases from Solanum lycopersicum.

Recent studies have confirmed that chlorophyllase (CLH), a long-found chlorophyll (Chl) dephytylation enzyme for initiating Chl catabolism, has no function in leaf senescence-related Chl breakdown. Yet, CLH is considered to be involved in fruit degreening and responds to external and hormonal stimuli. The purpose of this work was to elucidate in detail the biochemical, structural properties, and gene expression of four CLHs from the Solanum lycopersicum genome so as to understand the roles of Solanum lycopersicum chlorophyllases (SlCLHs). SlCLH1/4 were the predominantly expressed CLH genes during leaf and fruit development/ripening stages, and SlCLH1 in mature green fruit was modulated by light. SlCLH1/2/3/4 contained a highly conserved GHSXG lipase motif and a Ser-Asp-His catalytic triad. We identified Ser159, Asp226, and His258 as the essential catalytic triad by site-directed mutagenesis in recombinant SlCLH1. Kinetic analysis of the recombinant enzymes revealed that SlCLH1 had high hydrolysis activities against Chl a, Chl b, and pheophytin a (Phein a), but preferred Chl a and Chl b over Phein a; SlCLH2/3 only showed very low activity to Chl a and Chl b, while SlCLH4 showed no Chl dephytylation activity. The recombinant SlCLH1/2/3 had different pH stability and temperature optimum. Removal of the predicted N-terminal processing peptide caused a partial loss of activity in recombinant SlCLH1/2 but did not compromise SlCLH3 activity. These different characteristics among SlCLHs imply that they may have different physiological functions in tomato.

Integrated omics analysis identified genes and their splice variants involved in fruit development and metabolites production in Capsicum species.

To date, several transcriptomic studies during fruit development have been reported; however, no comprehensive integrated study on expression diversity, alternative splicing, and metabolomic profiling was reported in Capsicum. This study analyzed RNA-seq data and untargeted metabolomic profiling from early green (EG), mature green (MG), and breaker (Br) fruit stages from two Capsicum species, i.e., C. annuum (Cann) and C. frutescens (Cfrut) from Northeast India. A total of 117,416 and 96,802 alternatively spliced events (AltSpli-events) were identified from Cann and Cfrut, respectively. Among AltSpli-events, intron retention (IR; 32.2% Cann and 25.75% Cfrut) followed by alternative acceptor (AA; 15.4% Cann and 18.9% Cfrut) were the most abundant in Capsicum. Around 7600 genes expressed in at least one fruit stage of Cann and Cfrut were AltSpli. The study identified spliced variants of genes including transcription factors (TFs) potentially involved in fruit development/ripening (Aux/IAA 16-like, ETR, SGR1, ARF, CaGLK2, ETR, CaAGL1, MADS-RIN, FUL1, SEPALLATA1), carotenoid (PDS, CA1, CCD4, NCED3, xanthoxin dehydrogenase, CaERF82, CabHLH100, CaMYB3R-1, SGR1, CaWRKY28, CaWRKY48, CaWRKY54), and capsaicinoids or flavonoid biosynthesis (CaMYB48, CaWRKY51), which were significantly differentially spliced (DS) between consecutive Capsicum fruit stages. Also, this study observed that differentially expressed isoforms (DEiso) from 38 genes with differentially spliced events (DSE) were significantly enriched in various metabolic pathways such as starch and sucrose metabolism, amino acid metabolism, cysteine cutin suberin and wax biosynthesis, and carotenoid biosynthesis. Furthermore, the metabolomic profiling revealed that metabolites from aforementioned pathways such as carbohydrates (mainly sugars such as D-fructose, D-galactose, maltose, and sucrose), organic acids (carboxylic acids), and peptide groups significantly altered during fruit development. Taken together, our findings could help in alternative splicing-based targeted studies of candidate genes involved in fruit development and ripening in Capsicum crop.

Delaying ripening using 1-MCP reveals chilling injury symptom development at the putative chilling threshold temperature for mature green banana.

Storage at the putative chilling threshold temperature (CTT) to avoid chilling injury still limits postharvest handling of tropical fruit like banana in that ripening may occur at the CTT. To determine whether chilling injury (CI) symptoms would develop in mature green (MG) banana fruit if the CTT exposure was extended by inhibiting ethylene action and thus ripening, 1-methylcyclopropene (1-MCP) was applied. Individual ‘fingers’ from multiple ‘clusters’ of MG bananas were either immersed in water or 50 μg L−1 1-MCP (a.i.) solution and each treatment was divided into three subgroups for storage at 5.0°C (severe CI), 13.0°C (mild CI), or 14.0°C (CTT) ± 0.1°C. 1-MCP delayed ripening in terms of color change for 10 days for fruit stored at the CTT. Ethylene production by fruit at 5.0°C remained around 0.04 ng kg−1 s−1 with no obvious increase during 31-day storage. Ethylene production at 14.0°C (−1-MCP/+1-MCP) increased on Day 33 while increasing on Day 38 for 13.0°C fruit without 1-MCP and on Day 39 for fruit with 1-MCP. Peak climacteric ethylene occurred on Days 44 and 39 for 13.0 and 14.0°C fruit without 1-MCP, respectively, and on Days 59 and 51 for 13.0°C and 14.0°C 1-MCP-treated fruit, respectively. As hypothesized, longer exposure of MG banana fruit to the CTT of 14.0°C without onset of ripening as was allowed by prior 1-MCP treatment allowed CI to develop at that normally non-chilling temperature. Vascular browning was the first visual and most sensitive CI symptom in the experiment and was observed on Day 4 at 5.0°C, Day 10 at 13.0°C, Day 19 at 14.0°C without 1-MCP, and on Day 28 at 14.0°C with 1-MCP. Using a 1-MCP pre-treatment to remove the influence of ethylene from bananas stored at 13°C or 14°C also resulted in slight reduction in vascular browning severity. In conclusion, a putative safe temperature may become a CI temperature if the shelf-life-limiting factor is removed, allowing longer exposure. Chilling at the CTT caused relatively mild injury on fruit, and vascular browning is a sensitive indicator of CI status, while the light-adapted quantum yield of photosystem II [Y(II)] could be a non-destructive indicator of early CI stress in MG banana. Fruit at 13.0/14.0°C developed CI symptoms slightly later with 1-MCP than without 1-MCP. This suggests that ethylene might be involved in early CI symptom development.

Efficacy and Comparison of Different Strategies for Selenium Biofortification of Tomatoes

At appropriate concentrations, selenium (Se) is beneficial for humans. Tomato appears to be one of the best commodities for producing Se-biofortified fruit for dietary supplementation. To assess the efficacy of different enrichment protocols, a total of four on-plant and off-plant trials were conducted. Hydroponically grown tomato plants were sprayed with: (i) chemically synthesized Se nanoparticles (SeNPs) at 0, 1, and 1.5 mg Se L−1 at blooming; (ii) sodium selenate (Na2SeO4) or SeNPs solution at 0, 5, and 10 mg Se L−1 when the fruit entered the immature green stage. With regard to the off-plant trials, harvested mature green fruit were immersed in Na2SeO4 solution: (iii) at 0, 5, 10, and 20 mg Se L−1 for 15 s under a vacuum; (iv) at 0, 40, and 80 mg Se L−1 for 1 h. Spraying Na2SeO4 induced higher Se accumulation in plant tissue than SeNPs: both protocols were effective in enriching tomatoes. Postharvest Se enrichment via vacuum infiltration caused textural damage, whereas passive immersion in solution induced fruit Se accumulation without causing any damage. SeNPs appear to be quantitatively less effective than Na2SeO4, but might be environmentally safer. Elemental Se carried by NPs may be more easily incorporated into organic forms, which are more bioavailable for humans. Passive immersion may represent an alternative Se-enrichment strategy, allowing for the biofortification of harvested tomato fruit directly, with lower risks of environmental pollution.

Study The Ability Storage of Six Olive Fruit Cultivars Grown in Zakho Region

Green mature olive fruit (Olea europaea L.) of six cvs. (Basheqi, Sorani, Khilkhali, Manzanillo, Chemlali, Frantoio) were harvested from trees grown in Zakho Nursery, Zakho District, Dohuk governorate, Kurdistan region/Iraq. Samples of each cultivar were placed in plastic bags and stored at 6˚C and 85-90%RH for three different periods (2, 3 and 4) months to evaluate their postharvest physiology and quality changes. Estimated were made on parameters such as (weight loss, TSS, total sugar, pulp stone ratio, fruit peel color development, dry weight, fruit decay and oil content). The results showed that Basheqi cv. Superior &nbsp;other cvs. in weight loss and dry weight, while sorani cv. surpassed significantly in TSS, total sugars. Khilkhali cv. exceeded in pulp stone ratio and fruit peer color development. Chemlali cv. gave the highest value in oil content and fruit decay. After sweetening the fruit, Chemlali and Basheqi cv. recorded significantly maximum value of oil. Prolonged storage period to 3 and 4 months significantly increased weight loss, TSS, total sugar, pulp stone ratio, fruit peer color development, oil content and fruit decay, while decreased dry weight. The maximum dry weight was obtained when fruit stored for 2 months

Growth Temperature Influences Postharvest Quality and Cold Tolerance of Green Harvested Dwarf Tomatoes During Storage

Effect of cultivation temperature during the phase of flowering and fruit development on tomato quality was investigated. Plants of two dwarf tomato cultivars “Ponchi Re” and “Tarzan,” were subjected to three different growth temperatures: 16, 22, or 28°C, starting at the flowering phase. Mature green fruit was harvested and subjected to shelf life at 20°C for 20 days or first stored at 4°C for 15 days, and then placed under shelf life conditions. Fruit quality was determined through red color development, soluble solid content (SSC), softening, weight loss, and cold tolerance. Higher cultivation temperature increased development and production of fruit. Deviation from the 22°C growth temperature led to increased soluble solid content in both cultivars, and smaller fruit diameter in “Tarzan.” Fruit grown at lower temperature had delayed color development during shelf life, and this was further delayed by prior cold storage. “Tarzan” showed more chilling injury (CI) symptoms than “Ponchi Re.” In our experiment, SSC can be manipulated by modulating cultivation temperature, but that it is not associated with CI tolerance. Delayed color formation at the lowest growth temperature observed in “Ponchi Re” tomatoes could be resulted in lower lycopene levels leads to lower ROS scavenging capacity. For “Tarzan” tomatoes, higher firmness at harvest, less softening, and lower weight loss during cold storage in fruit from the lowest cultivation temperature might positively correlated with increased membrane integrity, resulting in increased CI tolerance. This indicates that CI incidence depends on growth temperature and is cultivar dependent in dwarf tomato fruit.

Chitosan oligosaccharide treatment improves quality attributes of tomato fruit stored under room temperature

Effect of chitosan oligosaccharide (COS), a natural product of low-cost and non-toxic with high biological activities, on quality attributes of tomato during post-harvest storage was investigated. Mature green tomato fruit were treated with 0.5 g L−1 COS and stored under room temperature. The results showed that COS was effective in improving fruit quality as revealed by redder color skin, higher content of nutrients such as carotenoids (lycopene and β-carotene) and vitamin C, and increased emissionb of flavor-associated volatiles (1-penten-3-one, heptanal, (E)-2-heptenal, 2-phenylacetaldehyde, 2-phenylethanol, 2-isobutylthiazole and β-ionone). The increased content of carotenoids upon COS treatment was correlated with the elevated expression levels of carotenogenic genes such as SlDXS, SlGGPS, SlPSY1, SlPDS, SlZDS, and SlLCY-B2. Moreover, COS-treated fruit exhibited accelerated occurrence of climacteric ethylene peak, enhanced ethylene production, and elevated expression of genes involved in ethylene biosynthesis (SlACS2, SlACS4, and SlACO1), perception (SlETR3), and response (E4 and E8), implying that COS might regulate fruit ripening and quality by enhancing ethylene biosynthesis and signaling. These findings help to extend our understanding of the function of COS in fruit ripening and provide a new strategy to improve tomato fruit quality during room temperature storage.

Irradiation-induced lenticel discolouration in ‘B74’ mango fruit is modulated by ripeness

ABSTRACT As a disinfestation treatment, irradiating unripe ‘B74’ mango can result in severe Irradiation-Induced Lenticel Discolouration (IILD). We tested the hypothesis that ‘B74’ fruit sensitivity to IILD would reduce as fruit ripen such as to mitigate skin damage. In two growing seasons, ‘B74’ fruit were sampled from five commercial farms, held for periods of 2–12 d at 20°C, treated with γ-irradiation at various doses from 0 Gy to 800 Gy, and assessed for external quality up to the ripe stage. Regardless of dose, irradiating ripening fruit at ~70% yellow skin reduced IILD severity on the ripened fruit by 36–47% compared to irradiating unripe green mature fruit at ~10% yellow skin. Irradiation of ripening fruit at 300–800 Gy consequently resulted in 74–100% marketable fruit at ripe compared to 5–59% for irradiation of the green mature fruit. Irradiating ripening fruit also minimised delays in loss of green skin during ripening. ‘B74’ fruit sensitivity to IILD decreases as fruit ripen and so delaying γ-irradiation until the fruit have partially ripened may be a commercially viable option to reduce quality loss due to IILD. However, fruit would need to be marketed quickly to compensate for a shorter post-treatment shelf-life.

Utilization of over matured fruit waste of Spine gourd (Momordica dioca Roxb.) as a source of anthelmintic bioactive constituents

To study the difference in the accumulation of bioactive constituents in Spine gourd (Momordica dioica Roxb.), the changes in its phenolic compounds at mature green (fruit utilized) and ripe red (fruit wasted) stages were analysed, and it was correlated with their antioxidant and anthelmintic potential. The highest total phenolic content was observed in ripe peel ethyl acetate (RPEA), tannins in ripe seed hexane (RSH) and flavonoid in ripe peel ethanol (RPE) extracts. UPLC–MS analysis identified 15 phenolic compounds in the extracts. The highest antioxidant potential was shown by RSH in DPPH (IC50 1.47 mg/ml), RPEA in ABTS (IC50 2.40 mg/ml), and mature peel water (MPeW) extract in FRAP assays (0.58 μg trolox equivalent per g dw). RPE induced the highest anthelmintic activity against Caenorhabditis elegans in egg hatch assay (LC50 - 0.02 mg/ml), and adult worm mortality assay (LC50 -1.44 mg/ml), as well as 100% death of infective juveniles in Heterorhabditis indica (50 mg/ml). Correlation studies and Principal Component Analysis (PCA) indicated the relationship of catechins, quercetin, kaempferol, rutin, and gallic acid to anthelmintic activity. The study showed that the ripe stage of Spine gourd, which gets disposed of as postharvest waste, had better anthelmintic activity, and it can be utilized for the development of food formulations with anthelmintic potential.

Ultrasound‐assisted extraction of essential and toxic elements from pepper in different ripening stages using Box–Behnken design

The influence of extraction parameters on the ultrasonically assisted extraction (UAE) of K, Na, Ca, Mg, Zn, Cu, Fe, Mn, Cr, Se, Mo, Li, Al, B, Pb, Hg, Cd, As, and Ni was studied to determine the conditions when a minimum of essential and maximum of toxic elements is leached from peppers, depending on its ripening stage. The effect of process variables was investigated by using Box–Behnken design. Each essential element had a different optimal condition for minimal leaching, while the toxic elements were predominantly extracted with acetic acid solution as extractant. The highest correlation between extraction conditions and concentration of extracted elements was found for aqueous extracts of mature green pepper. The concentration of acetic acid highly influenced the leaching of elements and a strong correlation between the concentration of Al, B, Fe, and Mn, and the UAE experimental conditions were observed. Practical applications This study investigates the leaching of minerals and heavy metals present in vegetables to the most commonly used media (water and acetic acid) during processing and canning. The data from this study may be useful for improving the quality of processed pepper products due to new information on how different parameters influence these losses (ripening stage of peppers, medium/solvent used for preparation, or storage, applied temperatures, time, mass to volume ratio). Essential elements are better preserved during the processing of intermediate breaker and mature red pepper compared to green mature fruits. Better retention of essential elements in the breaker and mature red pepper (that are mostly used in industrial processing) can be achieved by reducing the contact time with water, as well as mass to volume ratio. Leaching of toxic elements Al, Hg, and As can be improved with an acetic acid solution.

A study on antibacterial efficacy of different extracts of Artocarpus chama fruits and identification of bioactive compounds in the most potent extract

This study is designed to evaluate the antibacterial potential of various extracts of mature green fruits of Artocarpus chama with the identification of bioactive compounds. The antibacterial efficacy was tested against eight pathogenic bacteria using standard antibiotics as the positive control. Antibacterial bioassay was performed by measuring zone of inhibition, Minimum Inhibitory Concentrations (MIC), and Minimum Bactericidal Concentrations (MBC). The most effective extract was further subjected to preliminary phytochemical tests, Thin Layer Chromatography (TLC), and Fourier Transform Infrared analysis. Ethyl acetate extract (EAAC) was found to be the most effective extract producing an inhibition zone of 45.50 ± 0.50 mm against Pseudomonas aeruginosa MTCC 2453. Effective spots (ES) (Rf=0.37) of EAAC separated by TLC analysis were subjected to indirect contact bio-autography for evaluating their efficacies against the tested bacterial strains. Values of MBC/MIC for the extract ranged from 1.20 to 1.80 (&lt;2) indicating their bactericidal property. Gas Chromatography-Mass Spectroscopy analysis of ES was performed for the identification of bioactive antibacterial compounds. Alkaloids, saponins, steroids, terpenoids, and an array of functional groups in EAAC were detected. MICs of ES ranged from 6 - 10 µg/ml. Four bioactive compounds in ES were detected in GC-MS analysis. Thus, this study revealed that ethyl acetate extract of A. chama fruits contained several bioactive compounds with promising bactericidal properties against tested strains of both Gram-positive and Gram-negative pathogenic bacteria.

Analyses of key gene networks controlling carotenoid metabolism in Xiangfen 1 banana

BackgroundBanana fruits are rich in various high-value metabolites and play a key role in the human diet. Of these components, carotenoids have attracted considerable attention due to their physiological role and human health care functions. However, the accumulation patterns of carotenoids and genome-wide analysis of gene expression during banana fruit development have not been comprehensively evaluated.ResultsIn the present study, an integrative analysis of metabolites and transcriptome profiles in banana fruit with three different development stages was performed. A total of 11 carotenoid compounds were identified, and most of these compounds showed markedly higher abundances in mature green and/or mature fruit than in young fruit. Results were linked to the high expression of carotenoid synthesis and regulatory genes in the middle and late stages of fruit development. Co-expression network analysis revealed that 79 differentially expressed transcription factor genes may be responsible for the regulation of LCYB (lycopene β-cyclase), a key enzyme catalyzing the biosynthesis of α- and β-carotene.ConclusionsCollectively, the study provided new insights into the understanding of dynamic changes in carotenoid content and gene expression level during banana fruit development.

The Response of Tomato Fruit Cuticle Membranes Against Heat and Light.

Two important biophysical properties, the thermal and UV-Vis screening capacity, of isolated tomato fruit cuticle membranes (CM) have been studied by differential scanning calorimetry (DSC) and UV-Vis spectrometry, respectively. A first order melting, corresponding to waxes, and a second order glass transition (Tg) thermal events have been observed. The glass transition was less defined and displaced toward higher temperatures along the fruit ripening. In immature and mature green fruits, the CM was always in the viscous and more fluid state but, in ripe fruits, daily and seasonal temperature fluctuations may cause the transition between the glassy and viscous states altering the mass transfer between the epidermal plant cells and the environment. CM dewaxing reduced the Tg value, as derived from the role of waxes as fillers. Tg reduction was more intense after polysaccharide removal due to their highly interwoven distribution within the cutin matrix that restricts the chain mobility. Such effect was amplified by the presence of phenolic compounds in ripe cuticle membranes. The structural rigidity induced by phenolics in tomato CMs was directly reflected in their mechanical elastic modulus. The heat capacity (Cprev) of cuticle membranes was found to depend on the developmental stage of the fruits and was higher in immature and green stages. The average Cprev value was above the one of air, which confers heat regulation capacity to CM. Cuticle membranes screened the UV-B light by 99% irrespectively the developmental stage of the fruit. As intra and epicuticular waxes contributed very little to the UV screening, this protection capacity is attributed to the absorption by cinnamic acid derivatives. However, the blocking capacity toward UV-A is mainly due to the CM thickness increment during growth and to the absorption by flavone chalconaringenin accumulated during ripening. The build-up of phenolic compounds was found to be an efficient mechanism to regulate both the thermal and UV screening properties of cuticle membranes.

Engineering the polyphenolic biosynthetic pathway stimulates metabolic and molecular changes during fruit ripening in "Bronze" tomato.

The metabolic engineered Bronze tomato line is characterized by the constitutive over-expression of the VvStSy gene encoding a structural protein responsible for the stilbenoids biosynthesis and the fruit-specific over-expression of AmDel/Rosea1 and AtMYB12 genes encoding transcription factors that activate the polyphenol biosynthetic pathway. This tomato line is known for the increased levels of polyphenols in ripe fruits and for beneficial health promoting antioxidant and anti-inflammatory effects. In this study we analyzed the transcriptional and metabolic profiling in mature green, breaker, orange and ripe fruits compared to the normal tomato counterparts during ripening, to unravel the effect of regulatory and structural transgenes on metabolic fluxes of primary and secondary metabolisms. Our results showed that the shikimate synthase (SK) gene was up-regulated in the Bronze fruit, and the transcriptional activation is consistent with the metabolic changes observed throughout fruit ripening. These results paralleled with a reduced level of simple sugars and malate, highlighting the consumption of primary metabolites to favor secondary metabolites production and accumulation. Finally, carotenoids quantification revealed a change in the lycopene/β-carotene ratio in the Bronze fruit as a consequence of significant lower level of the first and higher levels of the latter. The high polyphenols and β-carotene content displayed by the Bronze fruit at the later stages of fruit ripening renders this line an interesting model to study the additive or synergic effects of these phyto-chemicals in the prevention of human pathologies.

First report of banana freckle disease caused by Phyllosticta cavendishii in Mauritius

Banana (Musa sp.) is among the most important fruit crops grown in Mauritius with significant socioeconomic and cultural considerations. The annual production of banana approximates to around 8000 tonnes (Statistics Mauritius, 2018). Dwarf Cavendish is the main variety grown commercially in Mauritius. During the hot and humid month of February 2014, symptoms consisting of dark black spots were observed on unripe banana of Dwarf Cavendish from the region of Nouvelle Découverte (super humid zone). A disease incidence of more than 50% with a moderate to severe level of severity across the field was reported by the extension services of the Food and Agricultural Research and Extension Institute. On the fruits, the initial symptom was tiny reddish-brown spots, bordered by dark green water-soaked margins (Figure 1). As the spots enlarged and coalesced, the surface became rough and turned black. These spots had a rough texture like sand-paper, similar to the description described by Wong et al. (2012). Comparable symptoms were observed on the leaves (Figure 2). Results from a rapid island-wide survey showed that only the Cavendish-type banana varieties displayed symptoms of infection. Out of 98 banana fields surveyed (50.9 ha), 65% were affected. Morphological identification of the suspected fungal pathogen was done using a compound light microscope. A sterile needle was used to tease pycnidia on leaves in a drop of sterile water to release conidia, before being mounted in clear lactic acid for microscopic examination. Conidia (Figure 3) formed singly at the apex of the conidiogenous cell were hyaline, aseptate, oblong to ellipsoidal, coarsely guttulate and measured 7.1-15.6 × 4.4-8.3 μm. The apical mucilaginous appendage arising from the conidium was straight to curved and was 5.1-12.9 μm long. Spermagonia were 70–125 μm in diameter and 50–85 μm high. Dumbbell-shaped spermatia (Figure 4) were hyaline, aseptate, biguttulate and measured 7.5-9.5 × 1.3-1.8 μm. These morphological characters are consistent with the species description of Phyllosticta cavendishii (Wong et al., 2012). Lesions from 11 samples of leaf and fruit with fruiting bodies were ground in liquid nitrogen followed by genomic DNA extraction. Extraction of DNA was done on c. 50 mg fresh plant tissue using the Biosprint 15 DNA Plant Kit (Qiagen, Germany). Tissues were first homogenized using a Tissuelyser (Qiagen, Germany) in a 2 ml microcentrifuge tube containing a 3 mm metal bead for two 30 second bursts at 30Hz. Two microliters of the eluted DNA was used as template in an ITS PCR amplification using AmpliTaq Gold 360 Mastermix (Applied Biosystems, USA) and 0.5 μM each of primers GMF1 and GMR2 (Wong et al., 2012). Thermal cycling conditions were 95°C for 10 min followed by 40 cycles of 95°C for 30 sec, 55°C for 30 sec and 72°C for 1 min. Final extension of PCR products was done at 72°C for 10 min. Amplicons (550bp) were directly sequenced using the same primer pair. Resulting sequences were analysed using BlastN as well as by manual comparison to known sequences of Phyllosticta isolates which cause freckle disease of banana. The causal agent from all 11 samples tested was found to be Phyllosticta cavendishii. The ITS sequences were deposited in GenBank (Accession Nos. MW520341-MW520351) and at the Queensland Plant Pathology Herbarium (BRIP 72048 to 72058). Pathogenicity was tested using twenty mature green healthy fruits of banana variety Dwarf Cavendish. Fruits were surface sterilised using 0.2% sodium hypochlorite for 2 mins, rinsed with sterilised distilled water and allowed to dry before inoculation. Ten fruits were artificially inoculated on the outer surface, clearly marked, with a conidial suspension of 106 conidia/ml, prepared from pycnidia extracted from field infected tissue. Control fruits were treated with sterile distilled water. All the fruits were covered with plastic bags for 48 hours and incubated at room temperature, 80% relative humidity and with a 12-hour photoperiod. After 7 days, typical minute black spots identical to those observed in the field, appeared on inoculated fruits, whereas controls remained healthy. The morphological characteristics of the fungus were consistent with those previously observed, hence fulfilling Koch's postulates. To our knowledge, this is the first report of Phyllosticta cavendishii causing banana freckle disease in Mauritius. The authors acknowledge the Centre for Plant Science, Queensland Alliance for Agriculture and Food Innovation for the molecular identification of Phyllosticta cavendishii and also Dr Yu Pei Tan from the Brisbane Plant Pathology Herbarium for accessioning isolates and submission into GenBank.

Mass Spectrometry Imaging Analysis of Metabolic Changes in Green and Red Tomato Fruits Exposed to Drought Stress

Plant metabolism is altered in response to various environmental changes. In vegetable crops such as tomato (Solanum lycopersicum), the metabolic composition of fruits varies depending on the variety or cultivar as well as the cultivation method used. Few studies have examined the metabolic fluctuations in fruits under stress conditions, such as drought. We previously examined the metabolomes of mature green tomato fruits, which undergo drastic changes in chemical composition during ripening, and mature red fruits in response to drought stress. We detected or predicted fluctuations in the levels of fatty acids and phospholipid constituents, such as inositol and ethanolamine. In this study, we determined the localizations of these metabolites in fruits using mass spectrometry imaging. The accumulation patterns of stearic acid and palmitic acid were similar, but unlike these fatty acids, oleic acid accumulated to high levels in the placenta. Inositol is involved in various physiological processes; under drought conditions, this metabolite is synthesized by a different pathway compared to under normal conditions. The biosynthesis of pectin, a component of the gel surrounding the seeds, was suppressed under drought stress but increased in seeds. We propose that under drought conditions, a shift to phospholipid biosynthesis occurs that protects seeds from dehydration.

Evaluation of Anthracnose Resistance in Pepper (Capsicum spp.) Genetic Resources

Anthracnose (Colletotrichum spp.), is one of the major yield losing fungal disease in both pre- and post-harvest stage of pepper (Capsicum spp.) production worldwide. Among the Colletotrichum spp., C. acutatum has strong pathogenicity, which infects both immature and mature pepper fruit leads to severe economic losses in pepper production. Inheritance of anthracnose disease resistance was evaluated with 3738 pepper genetic resources which was collected from different countries and conserved at Korean genebank. The resistance analysis against pepper anthracnose (C. acutatum) was performed on detached mature green and red fruits under laboratory conditions by spray (non-wounding) and microinjection (wounding) inoculation methods. In the primary screening, about 261 accessions were appeared to be resistant against C. acutatum in spray inoculation. The resistant accessions were further evaluated with microinjection (wounding) inoculation method using the fungal (C. acutatum) isolate of pepper anthracnose. There were highly significant differences in the disease severity and distribution of disease rating scale, considering all the sources has significant genetic variation. Finally, the anthracnose resistant pepper accessions have been validated with cleaved amplified polymorphic sequence (CAPS) and high-resolution melting (HRM) markers in which, the CAPS and HRM marker analysis showed four types of genotypes such as resistant (R), susceptible (S), heterozygous (H) and Unidentified type (UT) or not detection. The Capsicum accessions showing high level of resistance to the pathogen could be used as source material in breeding programs for resistance to anthracnose disease.