Fruit Pericarp Research Articles

Influence of genetic and environmental factors on the contents of carotenoids and phenolic acids in red pepper fruits (Capsicum annuum L.)

Red pepper is enriched in antioxidant components, such as carotenoids, phenolic compounds, and vitamins. In this study, we investigated the natural variability in the content of carotenoids and phenolic acids in 11 red pepper cultivars grown in two locations in South Korea during 2016, 2017, and 2018. Seven carotenoids and six phenolic acids, including soluble and insoluble forms, were detected in the red fruit pericarps. The major carotenoids were β-carotene (40%) and capsanthin (20%). The content of insoluble phenolic acids was higher than that of soluble phenolic acids because of the large amount of insoluble p-coumaric acid. The statistical analysis of combined data showed significant differences among varieties, locations, and years for most of the measured components. The results from variance component analysis indicated that the effects of location, year and the interaction of location and year mainly accounted for the variation in carotenoids, whereas variations in phenolic acid content were attributed to year and variety. In addition, the results of principal component analysis and orthogonal partial least-squares discriminant showed that carotenoids were well discriminated by location and year, whereas phenolic acids were distinctively separated only by year. The data from this study could explain the natural variation in the content of carotenoids and phenolic acids in red pepper fruits by genotype and environment.

Application of Essential Oils for Maintaining Postharvest Quality of ‘Rongrien’ Rambutan Fruit

The postharvest quality of rambutan fruits (Nephelium lappaceum Linn.) is mainly influenced by dehydration, which causes browning of the peel and spinterns. This research investigated the effects of some essential oils—from citronella, clove, kaffir lime, and lemongrass—on ‘Rongrien’ rambutan fruit quality during storage at 13 °C. Screening of effective concentrations from 0.01 to 0.16% was conducted for each essential oil. The results showed that, of the essential oil treatments tested, a kaffir lime oil coating of 0.01% could best maintain the quality of fruits, reducing both weight loss and browning of the peel and spinterns. However, essential oil concentrations exceeding 0.04% severely damaged the fruit pericarp, in which scores of spintern browning were higher than those of peel browning. These results suggest that kaffir lime oil can maintain the postharvest quality of ‘Rongrien’ rambutan fruit as a supplement in some edible coatings.

Impacts of exogenous ROS scavenger ascorbic acid on the storability and quality attributes of fresh longan fruit

The impacts of reactive oxygen species (ROS) scavenger ascorbic acid (AsA) treatment on the storability and quality attributes of ‘Fuyan’ longan fruit were explored. Compared to control samples, the treatment of 4 g L−1 AsA solution clearly reduced fruit weight loss, indexes of fruit disease and pericarp browning, retained higher percentage of commercially acceptable fruit, higher values of chromaticity a∗, chromaticity b∗, and chromaticity L∗, delayed pigment degradation in longan pericarp, and retarded the decreases of nutritive ingredients in longan pulp. When stored for 6 d, vitamin C (0.08 g kg−1), sucrose (20.70 g kg−1), total soluble sugar (56.32 g kg−1), and total soluble solids (12.4%) in AsA-treated fruit displayed the clearly higher contents than those in control samples. These data suggested that the treatment of exogenous ROS scavenger AsA could effectively enhance the quality attributes and storability of postharvest longan fruit, thereby lengthen their postharvest shelf-life.

Alleviation of Postharvest Chilling Injury of Carambola Fruit by γ-aminobutyric Acid: Physiological, Biochemical, and Structural Characterization.

Chilling injury is a physiological disorder affecting the quality of carambola fruit. In the present study, the effect of exogenous γ-aminobutyric acid (GABA) on CI development in carambola fruit during storage at 4°C for 15 days was investigated. The results showed that 2.5-mM GABA reduced CI index, maintained pericarp lightness, and decreased the electrolyte leakage (EL) and malondialdehyde content (MDA) while increased the superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT) enzyme activities. Endogenous GABA content was significantly higher in the treated fruit than in the control fruit during the whole storage. Besides, the treatment promoted the accumulation of proline and ascorbic acid (AsA) under chilling stress. Compared to the control, GABA-treated fruit exhibited a higher activity of phenylalanine ammonia-lyase (PAL) and total phenolic compounds, and a lower activity of polyphenol oxidase (PPO). In addition, the Safranin O/fast green staining revealed via microscopic images that the GABA treatment reduced the cell walls degradation of carambola fruit. Moreover, the results displayed a lower activity of phospholipase D (PLD) and lipoxygenase (LOX) enzymes, which coincided with a higher content of oleic acid (C18:1), linoleic acid (C18:2n6), and α-linolenic acid (C18:3n3) after 15 days of treatment, leading to the maintenance of the integrity and prevention of the membrane of the rapid softening of carambola fruit. The findings of the present work showed particularly new insights into the crosstalk between GABA and fatty acids. GABA might preserve the pericarp of carambola fruit by increasing the content of the unsaturated fatty acid (UFA) γ-linolenic acid and reducing the saturated fatty acid (SFA) such as caproic acid (C6:0), caprylic acid (C8:0), myristic acid (C14:0), and palmitic acid (C16:0) progressively. GABA can be used as an appropriate postharvest technology for improving the quality of carambola fruit during low-temperature storage.

Anti-Obesity Effects of Matoa (Pometia pinnata) Fruit Peel Powder in High-Fat Diet-Fed Rats.

Fruit peels, pericarps, or rinds are rich in phenolic/polyphenolic compounds with antioxidant properties and potentially beneficial effects against obesity and obesity-related non-communicable diseases. This study investigated the anti-obesity effects of matoa (Pometia pinnata) and salak (Salacca zalacca) fruit peel. Neither matoa peel powder (MPP) nor salak peel powder (SPP) affected the body weight, visceral fat weight, or serum glucose or lipid levels of Sprague–Dawley rats when included as 1% (w/w) of a high-fat diet (HFD). However, MPP significantly decreased the hepatic lipid level. MPP at a dose of 3% (w/w) of the HFD decreased body weight, visceral fat, and serum triglyceride levels as well as the hepatic lipid content. The inhibitory effect of MPP on hepatic lipid accumulation was not enhanced when its concentration was increased from 1% to 3% of the HFD. The anti-obesity effect of matoa was partly explained by the inhibitory effect of the matoa peel extract on fatty acid-induced secretion of ApoB-48 protein, a marker of intestinal chylomicrons, in differentiated Caco-2 cell monolayers. We identified hederagenin saponins that are abundant in MPP as potential anti-obesity substances. These results will contribute towards the development of functional foods with anti-obesity effects using the matoa fruit peel.

Fabrication and Biological Assessment of Antidiabetic α-Mangostin Loaded Nanosponges: In Vitro, In Vivo, and In Silico Studies.

Type 2 diabetes mellitus has been a major health issue with increasing morbidity and mortality due to macrovascular and microvascular complications. The urgent need for improved methods to control hyperglycemic complications reiterates the development of innovative preventive and therapeutic treatment strategies. In this perspective, xanthone compounds in the pericarp of the mangosteen fruit, especially α-mangostin (MGN), have been recognized to restore damaged pancreatic β-cells for optimal insulin release. Therefore, taking advantage of the robust use of nanotechnology for targeted drug delivery, we herein report the preparation of MGN loaded nanosponges for anti-diabetic therapeutic applications. The nanosponges were prepared by quasi-emulsion solvent evaporation method. Physico-chemical characterization of formulated nanosponges with satisfactory outcomes was performed with Fourier transform infra-red (FTIR) spectroscopy, differential scanning calorimetry (DSC), and scanning electron microscopy (SEM). Zeta potential, hydrodynamic diameter, entrapment efficiency, drug release properties, and stability studies at stress conditions were also tested. Molecular docking analysis revealed significant interactions of α-glucosidase and MGN in a protein-ligand complex. The maximum inhibition by nanosponges against α-glucosidase was observed to be 0.9352 ± 0.0856 µM, 3.11-fold higher than acarbose. In vivo studies were conducted on diabetic rats and plasma glucose levels were estimated by HPLC. Collectively, our findings suggest that MGN-loaded nanosponges may be beneficial in the treatment of diabetes since they prolong the antidiabetic response in plasma and improve patient compliance by slowly releasing MGN and requiring less frequent doses, respectively.

Effect of the Fe-HBED chelate on the nutritional quality of tomato fruits

Despite active debate about Fe fortification of food due to Fe fertilization, not much is known about influence of Fe availability on fruit quality, including tomatoes. Thus, our goal was to study the effect of Fe-HBED chelate on the nutritional quality of tomato (Solanum lycopersicum L.) fruits. The results showed that supraoptimal Fe-HBED supplementation caused cultivar-dependent detrimental changes in elemental status of fruit pericarp. Following Fe supplementation significant increases in xanthophylls and β-carotene contents were recorded. The results showed that Fe supplementation did not strongly interfere with metabolism of amino acids and other secondary metabolites, as contents of free amino acids, lycopene, soluble phenolics and flavonoids were not significantly affected. Moreover, differences in further lycopene trafficking into different branches of secondary metabolism (biosynthesis of carotenoids and xanthophylls) were observed. The data point out the important impact of Fe supplementation on nutritional quality (elemental composition and content of carotenoids and xanthophylls) of tomato fruits and warn against usage of Fe-oversupplied soil or Fe-enriched water for cultivation of tomatoes.

Effect of the Processing Parameters on the Fabrication of MgAl2O4 Foams.

Stable MgAl2O4 foams (7–21 vol.%) were manufactured using a natural extract from the pericarp of the soap-nut fruit, saponin being the main component, as the foaming agent. The soap-nut extract is soluble in water, biodegradable, non-toxic, and has similar properties to commercial tensoactives. The stability and characteristics of the porous structure of the ceramic foams were evaluated in terms of the amount of foaming agent, content of MgAl2O4 particles, time and speed of stirring of the slurry, type of agitator, and drying temperature. It was found that the foaming capacity decreased with the percent of foaming agent and ceramic, whereas the time and speed of stirring enhanced the foamability. Foaming trials showed that stirring aqueous slurries with 3 wt.% of soap-nut extract for 2 min at 1070 or 2120 rpm, depending on the type of agitator, produced stable MgAl2O4 foams when drying at 60 °C. The mechanism of foaming is discussed. The foams were sintered at 1400 °C for 1 h under an Ar atmosphere. Observation of the sintered foam structures in the scanning electron microscope revealed nearly spherical cells with very good interconnectivity and strength to be manipulated, making them suitable as preforms for manufacturing Al-based composites by pressureless infiltration.

GREENER METHODS OF CONTROL FOR MICROBIAL DISEASES OF POMEGRANATE USING COPPER OXIDE NANOPARTICLES AND BETEL LEAF EXTRACT

Pomegranate (Punica granatum) is an important exportable fruit crop of India that faces major losses when infected by fungal wilt and bacterial blight. The present investigation is aimed to isolate and identify the causative organism of the plant disease infecting the stem of pomegranate. The identification based on microscopic, morphological characterization and 18SrRNA sequencing confirms as Mariannaea elegans. The crude extracts of various leaves of plants viz Psidium guajava, Picrorhiza kurroa and Piper betel were used to evaluate antifungal activity using agar well diffusion method. Results confirm that ethanolic extract of Piper betel extract (0.5mg/ml) show zone of inhibition against Mariannea elegans. The research demonstrates that commonly used fungicides viz., Manocozeb/ Matalxy and Carbendazim showed very little inhibition as compared to the Piper betel ethanolic extracts and hence the latter proves to be a better and eco-friendlier control alternative. The present study was also aimed at finding remedies for bacterial blight. The blight pathogen was isolated from the fruit pericarp and identified using morphological and biochemical characters to be Xanthomonas axonopodis pv. punicae (Xap). Nanoparticles synthesized using green method, Copper oxide nanoparticles (1mg/ml) synthesized using Azadirachta indica leaf extract showed excellent inhibitory effect against the blight pathogen as compared to Bordeaux mixture, commonly used as an antimicrobial spray by farmers.

Antiproliferative activity of leaf, fruit pericarp essential oils of Syzygium palodense

BackgroundSyzygium palodense is an unexplored species endemic to the southern Western Ghats in India. PurposeHere we report the chemical profiles of essential oils (EOs) of the leaves and fruit pericarps of S. palodense and their antiproliferative activities against C6 glioma and Dalton's Lymphoma Ascites (DLA) cells. MethodsS. palodense leaves and fruit pericarp EOs were isolated by hydrodistillation and characterized by gas chromatographic (GC/FID, GC/MS) techniques. Antiproliferative activities of EOs were elucidated by MTT, phase contrast/fluorescent microscopic and flow cytometric assays. ResultsThirty six (99.92%) constituents were identified from S. palodense fruit pericarp EO, with (E)-β-ocimene (63.20%), myrcene (15.79%) and (Z)-β-ocimene (9.70%) as its major constituents. Sixty nine (99.40%) constituents were identified in the leaf EO, and the major ones were (E)-β-ocimene (30.58%), (E)-caryophyllene (14.23%), δ-selinene (13.89%), γ-himachalene (7.59%), myrcene (8.38%) and (Z)-β-ocimene (5.68%). Both leaf and fruit pericarp EOs showed significant cytotoxicity in C6 glioma and Dalton's Lymphoma Ascites (DLA) cells with very low CD50 values of 1.8, 1.2 µg/ml and 4.8, 1.1 µg/ml, respectively. MTT, phase contrast/fluorescent microscopic and flow cytometric assays revealed the cytotoxic mechanism of these EOs in C6 glioma and DLA cells as induction of apoptosis. ConclusionThis is the first report of the chemical profiles and biological activities of EOs of S. palodense. Both leaf and fruit pericarp EOs displayed strong antiproliferative activity (very low CD50 values) against C6 glioma and DLA cells.

Visualizing the spatial distribution of metabolites in Clausena lansium (Lour.) skeels using matrix-assisted laser desorption/ionization mass spectrometry imaging

Clausena lansium (Lour.) Skeels (Rutaceae) is a natural bioactive plant. Its roots, stems, leaves, and seeds are widely used in Chinese traditional and folk medicine. Although the characterization and functional analysis of bioactive components in Clausena lansium (Lour.) Skeels has been widely reported, the spatial distribution of these compounds within the main plant tissues remains undefined. Here, we adopted matrix-assisted laser desorption/ionization-mass spectrometry imaging (MALDI-MSI) to reveal the spatial distribution of active alkaloids, coumarins, sugars and organic acids in C. lansium. Using a combined wet and dry matrix covering method to enhance sensitivity, we detected alkaloids throughout the fruit including 3-methylcarbazole and murrastinine which were especially rich in the kernel tissues but were restricted to the stem xylem and medulla and in the leaf epidermal region. Interestingly, murrayanine and heptaphylline were mainly found in pulp tissues with very low content in the stems and leaves while girinimbine was only distributed within the outer kernel skin. Coumarins were mainly distributed in the fruit pericarp and leaf vein tissues but with no clear spatial specificity in stems. Lastly, hexoses were mainly evident in the fruit pulp, although sucrose was also found in the pericarp, pulp, and pulp fibers with citric acid being distributed throughout the fruit. The accurate spatial and chemical information obtained provides new insights into the specific accumulation of metabolites in individual tissues.

Genome-wide association study identifies QTL for eight fruit traits in cultivated tomato (Solanum lycopersicum L.)

Genome-wide association study (GWAS) is effective in identifying favorable alleles for traits of interest with high mapping resolution in crop species. In this study, we conducted GWAS to explore quantitative trait loci (QTL) for eight fruit traits using 162 tomato accessions with diverse genetic backgrounds. The eight traits included fruit weight, fruit width, fruit height, fruit shape index, pericarp thickness, locule number, fruit firmness, and brix. Phenotypic variations of these traits in the tomato collection were evaluated with three replicates in field trials over three years. We filtered 34,550 confident SNPs from the 51 K Axiom® tomato array based on < 10% of missing data and > 5% of minor allele frequency for association analysis. The 162 tomato accessions were divided into seven clusters and their membership coefficients were used to account for population structure along with a kinship matrix. To identify marker-trait associations (MTAs), four phenotypic data sets representing each of three years and combined were independently analyzed in the multilocus mixed model (MLMM). A total of 30 significant MTAs was detected over data sets for eight fruit traits at P < 0.0005. The number of MTA per trait ranged from one (brix) to seven (fruit weight and fruit width). Two SNP markers on chromosomes 1 and 2 were significantly associated with multiple traits, suggesting pleiotropic effects of QTL. Furthermore, 16 of 30 MTAs suggest potential novel QTL for eight fruit traits. These results facilitate genetic dissection of tomato fruit traits and provide a useful resource to develop molecular tools for improving fruit traits via marker-assisted selection and genomic selection in tomato breeding programs.

LC-Q-Orbitrap-MS/MS Characterization, Antioxidant Activity, and α-Glucosidase-Inhibiting Activity With In Silico Analysis of Extract From Clausena Indica (Datz.) Oliv Fruit Pericarps.

Clausena indica (Datz.) Oliv fruit pericarps (CIOPs) is an important agro-industrial by-product rich in active components. In this article, the effects of traditional and green deep eutectic solvents (DESs) on the high-performance liquid chromatography (HPLC) characterization, antioxidant activities, and α-glucosidase-inhibitory activity of phenolic extracts from CIOPs were investigated for the first time. The results showed that ChCl-Gly and Bet-CA had higher extraction efficiency for the total phenolic content (TPC, 64.14–64.83 mg GAE/g DW) and total flavonoid content (TFC, 47.83–48.11 mg RE/g DW) compared with the traditional solvents (water, methanol, and ethyl acetate). LC-Q-Orbitrap-MS/MS was adopted to identify the phenolic compositions of the CIOPs extracts. HPLC-diode array detection (HPLC-DAD) results indicated that arbutin, (–)-epigallocatechin, chlorogenic acid, procyanidin B1, (+)-catechin, and (–)-epicatechin were the major components for all extracts, especially for deep eutectic solvents (DESs). In addition, ChCl-Xyl and ChCl-Gly extracts showed higher antioxidant activities against 2,2-diphenyl-1-picrylhydrazyl (DPPH•), 2,2′-azino-bis (3-ethylbenzothiazoline-6-sulphonic acid (ABTS+•), ferric reducing antioxidant power (FRAP), reducing power (RP), and cupric ion reducing antioxidant capacity (CUPRAC) than extracts extracted by other solvents. A strong α-glucosidase-inhibiting activity (IC50, 156.25-291.11 μg/ml) was found in three DESs extracts. Furthermore, in silico analysis of the major phenolics in the CIOPs extracts was carried out to explore their interactions with α-glucosidase. Multivariate analysis was carried out to determine the key factors affecting the antioxidant activity and α-glucosidase-inhibiting activity. In short, DES can be taken as a promising solvent for valorization and recovery of bioactive compounds from agro-industrial by-products. The results verified that CIOPs can be used as a prospective source rich in bio-active compounds applied in the food and pharmacy industries.

Formulation and Evaluation of Mangosteen (Garcinia mangostana L.) Fruit Pericarp Extract Gel

The topical antioxidant product may be useful for the treatment of oxidative stress-related skin disorder. This research aimed to evaluate a topical gel formulation of Garcinia mangostana L. fruit pericarp (GMP) extract. GMP extract was formulated into a gel and characterized for its physical properties. The antioxidant activity was evaluated based on the radical 2,2-diphenyl-1-picrylhydrazyl (DPPH) scavenging activity. The ability of gel formulation to release GMP extract and promote skin delivery was estimated based on DPPH scavenging method and also compared to that of suspension form. The results showed that the GMP extract gel showed characteristics for topical application. The radical DPPH scavenging activity was confirmed both in GMP extract and GMP extract gel. In vitro study release showed that the GMP extract was released from gel. Some degree of GMP extract was also delivered into the shed snakeskin in vitro. When compared with the suspension form, GMP extract gel provided a more profoundly lower release.

Differential effects of excess calcium applied to whole plants vs. excised fruit tissue on blossom-end rot in tomato

Blossom-end rot can cause serious yield and quality losses to processing tomato producers, fresh market growers, and home gardeners alike. Blossom-end rot is often associated with calcium deficiency, though salt stress and even high concentrations of calcium salts can also cause blossom-end rot. The goal of this study was to characterize the negative effects of excess calcium compared to inadequate calcium at the whole plant and cellular level. Four calcium chloride levels (0 ppm, 10 ppm, 100 ppm, and 500 ppm) were applied daily to highly blossom-end rot susceptible processing tomato plants, starting at first flowering. Fruit were harvested 21–22 days after pollination. Blossom-end rot incidence and severity were lowest in the 10 ppm treatment. Blossom-end rot incidence was highest in the 0 ppm treatment and blossom-end rot severity was significantly increased in 500 ppm and 0 ppm treatments compared to 10 ppm CaCl2. No significant difference was found in the calcium content of tomato fruit harvested from plants treated with various levels of calcium. The soil drainage solution from the 500 ppm treatment had the highest conductivity, which was nearly 10 times higher than that of the 0 ppm and 10 ppm treatments. Daily plant water use was reduced in the 500 ppm treatment. Application of moderate calcium to tomato plants effectively reduced blossom-end rot incidence and severity, but excess levels of calcium did not reduce incidence and further increased blossom-end rot severity compared to moderate calcium application. Calcium applied to immature tomato fruit pericarp discs also inhibited blossom-end rot symptom development; however, excess calcium did not induce blossom-end rot symptoms. These results indicate that excess calcium induces blossom-end rot development due to effects at the whole plant level, but not due to excess calcium in the fruit tissue.

Integrative analysis of metabolome and transcriptome profiles provides insight into the fruit pericarp pigmentation disorder caused by \u2018Candidatus Liberibacter asiaticus\u2019 infection

BackgroundMandarin ‘Shatangju’ is susceptible to Huanglongbing (HLB) and the HLB-infected fruits are small, off-flavor, and stay-green at the maturity period. To understand the relationship between pericarp color and HLB pathogen and the effect mechanism of HLB on fruit pericarp coloration, quantitative analyses of HLB bacterial pathogens and carotenoids and also the integrative analysis of metabolome and transcriptome profiles were performed in the mandarin ‘Shatangju’ variety with four different color fruits, whole green fruits (WGF), top-yellow and base-green fruits (TYBGF), whole light-yellow fruits (WLYF), and whole dark-yellow fruits (WDYF) that were infected with HLB.Resultsthe HLB bacterial population followed the order WGF > TYBGF > WLYF > WDYF. And there were significant differences between each group of samples. Regarding the accumulation of chlorophyll and carotenoid, the chlorophyll-a content in WGF was the highest and in WDYF was the lowest. The content of chlorophyll-b in WGF was significantly higher than that in other three pericarps. There were significant differences in the total content of carotenoid between each group. WGF and TYBGF pericarps were low in phytoene, γ-carotene, β-cryptoxanthin and apocarotenal, while other kinds of carotenoids were significantly higher than those in WDYF. And WLYF was only short of apocarotenal. We comprehensively compared the transcriptome and metabolite profiles of abnormal (WGF, TYBGF and WLYF) and normal (WDYF, control) pericarps. In total, 2,880, 2,782 and 1,053 differentially expressed genes (DEGs), including 121, 117 and 43 transcription factors were identified in the three comparisons, respectively. The qRT-PCR confirmed the expression levels of genes selected from transcriptome. Additionally, a total of 77 flavonoids and other phenylpropanoid-derived metabolites were identified in the three comparisons. Most (76.65 %) showed markedly lower abundances in the three comparisons. The phenylpropanoid biosynthesis pathway was the major enrichment pathway in the integrative analysis of metabolome and transcriptome profiles.ConclusionsSynthesizing the above analytical results, this study indicated that different color pericarps were associated with the reduced levels of some carotenoids and phenylpropanoids derivatives products and the down-regulation of proteins in flavonoids, phenylpropanoids derivatives biosynthesis pathway and the photosynthesis-antenna proteins.

Water loss and pericarp browning of litchi (Litchi chinensis) and longan (Dimocarpus longan) fruit maintain seed vigor

Water loss is a key factor in pericarp browning during storage and transportation of litchi and longan fruit. However, whether this water loss is of biological significance is unclear. The loss of water in different tissues during browning of the two fruit, and the relationship between water loss and seed vigor were investigated. The pericarp of both fruit lost 60% of water after 4 days at 20 °C without packaging, in contrast, water loss in the aril and seed was insignificant. Water loss led to browning, a denser and thinner pericarp, correlating with a decrease in permeability to water of the pericarp. The seeds maintained 40% water content and 80% of them germinated when kept in the intact fruit after 12 days. In contrast, bare seeds stored without package retained 20% water content and germinated less than 10%. Germination was negatively correlated with fruit decay index. Phenols extracted from the pericarp after browning inhibited the growth of Peronophythora litchii more than those extracted before browning. Pericarp browning triggered by water loss of the tissue after harvest maintains seed vigor by preventing of dehydration and infection of the seeds.

Transcriptome and metabolome profiling revealing anthocyanin and phenolic acid biosynthetic mechanisms in sweet osmanthus pericarp

During the maturation process of sweet osmanthus fruit, its pericarp color gradually changes from green to purple-black. Moreover, the chemical composition changes in the pericarp of sweet osmanthus fruit during its color change; however, the mechanisms by which the major medicinal chemicals and anthocyanins are produced remain unclear. This study adopts a metabolomic approach to analyze the chemical composition of green, light purple, and purple-black pericarps during the sweet osmanthus fruit maturation process. Phenolic acids and lignans were more diverse and higher in the green pericarp than in the purple-black pericarp, especially chlorogenic acid and phillygenin that were upregulated by 1.78-and 4.55-fold, respectively, in the green pericarp, whereas flavonoids and anthocyanins were higher in the purple-black pericarp than in the green pericarp, especially cyanidin-3-O-rutinoside and peonidin-3-O-rutinoside that were upregulated by 6.68- and 16.98-fold, respectively, in the purple-black pericarp. Thus, the purple-black color of the sweet osmanthus pericarp is primarily because of a high content of cyanidin-3-O-rutinoside. Transcriptome sequencing analysis showed that the expression level of genes related to the phenolic acid and lignan synthesis pathways, such as HCT, CCoAOMT, CCR, and F5H, demonstrated significant upregulation in the green pericarp, whereas genes such as CHS, CHI, F3H, DFR, and ANS involved in the flavonoid metabolism pathway were significantly downregulated in the green pericarp. These gene expression differences result in a higher content of phenolic acids and lignans in the green pericarp and a higher content of anthocyanins in the purple-black pericarp. The results of this study provide a theoretical basis for the development and utilization of medicinal components, such as chlorogenic acid, phillygenin, and flavonoids in the pericarp of sweet osmanthus fruit for medicinal, health, and food additive use.

CRISPR/Cas9 mutants of tomato MICRORNA164 genes uncover their functional specialization in development.

Plant MICRORNA164 (miR164) plays diverse regulatory functions by post-transcriptional repression of certain NAM/ATAF/CUC-domain transcription factors. However, the involvement of miR164 in fleshy fruit development and ripening remains poorly understood. Here, de novo prediction of tomato (Solanum lycopersicum) MIR164 genes identified four genes (SlMIR164a-d), of which SlMIR164d has an atypically long pre-miRNA. The roles of the fruit expressed SlMIR164a, b, and d were studied by analysis of their Clustered Regularly Interspaced Short Palindromic Repeats mutants. The slmir164bCR mutant plants exhibited shoot and flower abnormalities characteristic of ectopic boundary specification, whereas the shoot and flower development of slmir164aCR and slmir164dCR mutants were indistinguishable from wild-type. Strikingly, the knockout of SlMIR164a practically eliminated sly-miR164 from the developing and ripening fruit pericarp. The sly-miR164-deficient slmir164aCR fruits were smaller than the wild-type, due to reduced pericarp cell division and expansion, and displayed intense red color and matte, instead of glossy appearance, upon ripening. We found that the fruit skin phenotypes were associated with morphologically abnormal outer epidermis and thicker cuticle. Quantitation of sly-miR164 target transcripts in slmir164aCR ripening fruits demonstrated the upregulation of SlNAM3 and SlNAM2. Specific expression of their miR164-resistant versions in the pericarp resulted in the formation of extremely small fruits with abnormal epidermis, highlighting the importance of their negative regulation by sly-miR164a. Taken together, our results demonstrate that SlMIR164a and SlMIR164b play specialized roles in development: SlMIR164b is required for shoot and flower boundary specification, and SlMIR164a is required for fruit growth including the expansion of its outer epidermis, which determines the properties of the fruit skin.

Transcriptome and genome re-sequencing analysis reveals differential expression patterns and sequence variation in pericarp wax metabolism-related genes in Ziziphus jujuba (Chinese jujube)

The fruit pericarp wax of jujube accessions with different cracking resistance show differences in morphology and wax chemical content. In this study, transcriptome and genome re-sequencing were used to analyze the differences in wax metabolism between jujube cultivars with different cracking resistance characteristics. The results showed that 431 differentially expressed genes were identified through transcriptome screening between the cracking-resistant cultivar ‘Linhuang No. 1’ and the cracking-susceptible cultivar ‘Muzao’ during the mature stage of fruit development. Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis annotated three wax metabolism pathways (involving eight wax metabolism-related genes). Information on gene sequence variation in the eight genes was obtained from genome resequencing, with sequence variation between the two cultivars found in the promoter region of the LOC107415896 gene, which encodes the biotin carboxyl carrier protein of acetyl-CoA carboxylase 2, chloroplastic (BCCP2) protein, where 107 bases were inserted in ‘Linhuang No.1’. As a result, the fatty acid concentration in the wax of ‘Muzao’ was lower than that of ‘Linhuang No. 1’, with the proportion of fatty acids with fewer than 16 C atoms in ‘Muzao’ accounting for a greater proportion of the total fatty acids. This indicated that the expression of the ‘Muzao’ LOC107415896 gene was affected. Our research has laid the foundation for further analysis of the function of jujube wax metabolism in the cracking-resistant fruit phenomenon.