First Report of Leaf Spot on Eriobotrya japonica Caused by Alternaria alternata in Southwest Korea

Loquat (Eriobotrya japonica) is a crop cultivated in Southwest Korea, covering an area of 101 ha and yielding 120 tons at harvest (KASS, 2024). Due to its high-income potential, the cultivation area is gradually expanding. In May 2023, 30% of leaf brown spots were observed on all three trees in the Suncheonman National Garden, Suncheon (3488'57.97" N, 12750'92.83" E). As the disease progressed, the brown spot gradually enlarged, turning greyish-ivory inside and forming concentric circles. Three leaf lesions from each tree were cut into 5 x 5 mm pieces, surface-sterilized with 70% ethanol for 1 min, and washed in sterile water three times to isolate the pathogen potentially responsible for these symptoms. The samples obtained were subsequently cultured on 1.5% water agar and then incubated in the dark at 25℃. A total of nine isolates were obtained, with three isolates from each of the three trees through single-spore isolation, namely SYP-1202-1 to 3, SYP-1202-4 to 6, and SYP-1202-7 to 9. The colonies reached 90 mm in diameter after 10 days on potato dextrose agar (PDA), initially dark green, and turned sooty gray after 2 weeks. The hyphae grown on a 0.6% KCl medium for 3 days produced long chains containing three to twelve conidia. The conidia were ellipsoidal or obpyriform in shape and light brown. The conidiophores were straight or curved, measuring 12.1-75.3 x 1.6-4.8 μm (n = 100). The primary and secondary conidia measured length × width of 19.1-60.6 × 6.1-14.4 μm and 8.4-27.8 × 3.5-9.5 μm (n = 100), respectively. The conidia had 1 to 7 transverse and 0 to 3 vertical septa. The morphology of the nine isolates was identical and consistent with Alternaria species (van der Waals et al., 2011; Woudenberg et al., 2015). For molecular identification, ITS (OR844500 to OR844508), GAPDH (OR866383 to OR866391), TEF1 (OR866392 to OR866400), RPB2 (OR866401 to OR866409), Alt a1 (OR866410 to OR866418), endoPG (OR866419 to OR866427), and OPA10-2 (OR866428 to OR866436) sequences from SYP-1202-1 to 9 showed a 100% (515 bp/515 bp), 100% (579/579), 100% (240/240), 100% (753/753), 95.1% (449/472), 100% (448/448), and 100% (634/634) identity with that of type strain A. alternata CBS 115152 (KP124348, KP124202, KP125124, KP124816, KP123896, KP124049, and KP124658, respectively). A pathogenicity test was conducted on three 5-year-old E. japonica cultivar Daebang trees in pots. The surface of the five leaves per tree was sterilized with 70% ethanol for 1 min. Before inoculation, the leaves were wounded with sterile needles and sprayed with the conidial suspension (1×106 conidia/ml) produced from a 1-week-old culture grown on PDA. In contrast, control leaves were sprayed with sterile distilled water. The inoculated leaves were wrapped with black plastic bags and kept at 100% relative humidity for two days. At seven days post-inoculation, symptoms were observed on the wounded leaves, whereas the nonwounded and control leaves did not exhibit any symptoms. The experiment was performed three times in the greenhouse. For each experiment, pathogens were reisolated from the two symptomatic leaves per plant. The identity of the reisolated pathogens was then confirmed via analysis of ITS and RPB2 genes, thereby confirming adherence to Koch's postulates. To the best of our knowledge, this is the first report of E. japonica being infected by A. alternata in Korea. This report provides important information to support effective disease control strategies for E. japonica in orchards in southern Korea.

Cardioprotective study of Eriobotrya japonica leaf extracts against carbon tetrachloride induced toxicity in rats

The Rosaceae family includes the evergreen subtropical tree known as Eriobotrya japonica Lindl (loquat). To test the effect of several E. japonica leaf extracts on shielding the heart from carbon tetrachloride (CCl4) cytotoxic effects, we employed carbon tetrachloride (CCl4), a highly toxic chemical, to cause cardiotoxicity in rats. The heart function enzymes that were examined were lactate dehydrogenase (LDH) and Creatine Kinase. When compared to both the hazardous and normal groups, it was discovered that the protective dose of ethyl acetate extract (200 mg/Kg) and aqueous extract (100 and 200 mg/Kg) lowered the cardiac indicators. Total protein, malondialdehyde (MDA), and non-protein sulfhydryls (NP-SH) indicators were used to assess myocardial oxidative stress. Rats pretreated with ethyl acetate (200 mg/Kg) and aqueous extract (100 and 200 mg/Kg) showed higher levels of total protein than the control group. When compared to the silymarin group, all of the loquat leaf extracts examined in this study increased the amount of the MDA enzyme. The data also demonstrated that, when compared to the results from the normal group, aqueous extract (100 and 200 mg/Kg) enhanced the amount of NP-SH. The histopathology showed that administration of all loquat leaf extracts at doses of (100 mg/kg, 200 mg/kg) before CCl4 intoxication greatly reduced the modifications that were exhibited by CCl4 and preserved cardiac muscles that were very equivalent to those of normal control. Based on the aforementioned data, we deduced that loquat leaf aqueous extract provided the highest protection for heart tissue against the effects of CCl4 intoxication. Through chemical examination of the methanolic extract, four flavonoids were extracted and identified. Their structures were found to be kaempferol-3-O-rhamnoside 1, quercetin-3-O-rhamnoside 2, quercetin-3,7 di-O-glycerides 3, and roseoside 4.

Fruits and Leaves

Increasing interest in new sources of secondary metabolites as biologically active substances has resulted in an advanced study of many plant species. Loquat (Eriobotrya japonica (Thunb.) Lindl. = Rhaphiolepis bibas (Lour.) Galasso & Banfi, Rosaceae family), an evergreen, subtropical fruit tree, native to China and Japan, but cultivated in southern countries of Europe, is a species commonly used in folk medicine and may be an excellent source of bioactive compounds. Therefore, the aim of the present study was to evaluate the profile of the phenolic constituents of E. japonica fruits and leaves originating from Tuscany (Italy), as well as their in vitro antioxidant and chemopreventive activities on human cancer cell lines breast adenocarcinoma (MCF-7), colon adenocarcinoma (Caco-2 and HT-29), and glioblastoma (U87MG). Results revealed that the extract of leaves displayed higher antioxidant and anticancer potential than the fruit extract and contained 25 individual phenolic compounds that have been characterized and quantified by the UPLC-PDA-MS method. The antiproliferative activity was correlated with the content of polyphenolic compounds indicating that both fruits and leaves are a good source of antioxidants and may be exploited as nutraceuticals enriching food or as components for the cosmetic/pharmaceutical industry.

Effects of Three Essential Oil Fumigation Treatments on the Postharvest Control of Botrytis cinerea and Their Efficacy as Preservatives of Cherry Tomatoes

Cherry tomatoes (Solanum lycopersicum) are becoming increasingly popular due to their nutrition and delicious flavor. However, cherry tomatoes are highly perishable and susceptible to various pathogenic microorganisms after harvest, such as Botrytis cinerea. In the pretest experiment, we screened out three kinds of plant essential oils (EOs) (Torreya grandis oil, Eriobotrya japonica oil, and Citrus medica oil) that have strong fungicidal activity on B. cinerea from cherry tomatoes. To further evaluate the postharvest preservation application prospect of these three oils for cherry tomatoes, the oils were extracted from different parts of three plants by hydrodistillation, and their chemical constituents were analyzed by gas chromatography-mass spectrometry. The main representative components of T. grandis oil, E. japonica oil, and C. medica oil were δ-cadinene (11.76%), transnerolidol (9.70%), and 5,7-dimethoxycoumarin (23.22%), respectively. These three EOs effectively inhibited the mycelial growth of B. cinerea in vitro, with EC50 values of 81.672, 144.046, and 221.500 μl/liter, respectively. Compared with the blank control and other oil treatments, the T. grandis oil (at a concentration of 200 µl/liter) fumigation treatment was more effective at inhibiting the growth rate of the pathogen. In addition, the phenolic content and phenylalanine ammonia lyase, β-1,3-glucanase, chitinase, and peroxidase activities of tomatoes significantly increased on the seventh day due to the T. grandis oil treatment. The present study shows that these three oils with high extraction rates have preservation potential for cherry tomatoes. Among these three EOs, T. grandis oil can be used to further develop preservative products as a fumigant.

Cacopsylla fuscicella Sp. Nov. (Hemiptera, Psyllidae), a New Loquat Pest in China

Psylloidea, commonly known as jumping plant-lice, have a phloem-sucking habit and strong specificity to their host plants. Within the Psyllidae family, the genus Cacopsylla Ossiannilsson, 1970 stands out as being the most diverse, with three species feeding on the genus Eriobotrya Lindl. In this study, a new psyllid species, Cacopsylla fuscicella sp. nov., was described from China. It is a pest of Eriobotrya japonica (Thunb.) Lindl. and has been cultivated as a commercial fruit tree for years. Illustrations of habitus, morphological structures, and its damage to loquat were also provided. The complete mitochondrial genome of C. fuscicella sp. nov. was sequenced and annotated. The phylogenetic tree inferred from the maximum likelihood analyses confirmed C. fuscicella sp. nov. as a member of the genus Cacopsylla. Genetic distances were generated to assess comparative genetic distances within Psyllinae.

Postharvest Biology and Technology of Loquat (Eriobotrya japonica Lindl.)

Loquat (Eriobotrya japonica Lindl.) fruit is a rich source of carotenoids, flavonoids, phenolics, sugars, and organic acids. Although it is classified as a non-climacteric fruit, susceptibility to mechanical and physical bruising causes its rapid deterioration by moisture loss and postharvest decay caused by pathogens. Anthracnose, canker, and purple spot are the most prevalent postharvest diseases of loquat fruit. Cold storage has been used for quality management of loquat fruit, but the susceptibility of some cultivars to chilling injury (CI) consequently leads to browning and other disorders. Various techniques, including cold storage, controlled atmosphere storage, hypobaric storage, modified atmosphere packaging, low-temperature conditioning, heat treatment, edible coatings, and postharvest chemical application, have been tested to extend shelf life, mitigate chilling injury, and quality preservation. This review comprehensively focuses on the recent advances in the postharvest physiology and technology of loquat fruit, such as harvest maturity, fruit ripening physiology, postharvest storage techniques, and physiological disorders and diseases.

Loquat (Eriobotrya japonica (Thunb) Lindl.): Evaluation of nutritional value, polyphenol composition, antidiabetic effect, and toxicity of leaf aqueous extract

ETHNOPHARMACOLOGICAL RELEVANCE

Loquat (Eriobotrya japonica (Thunb.) Lindl.) is an evergreen tree native to China, which is introduced in many Mediterranean countries. As in many ancient medical systems, loquat leaves have been used in Moroccan traditional medicine to treat diabetes and its complications.

AIM OF THE STUDY

This study aims to determine the nutritional and polyphenol composition and to evaluate the in vivo antidiabetic, and antihyperlipidemic properties and oral toxicity of a leaf aqueous extract (LLE) derived from loquat grown in Morocco.

MATERIALS AND METHODS

Energy value and fiber, fatty acids, minerals, vitamins, total carbohydrate, sugar, lipid, and protein contents were determined according to international methods committee guidelines. Polyphenol profiling was carried out using the HPLC-DAD method. Mice fed a high-fat and high-glucose (HFG) diet for 10 weeks were used as a model to assess the antidiabetic and antihyperlipidemic effects of a daily administration of LLE at three different doses (150, 200, 250 mg/kg body weight (BW)/day), in comparison with metformin (50 mg/kg BW/day) and pravastatin (20 mg/kg BW/day). The oral toxicity was determined following OECD 425 Guideline.

RESULTS

Loquat leaves were found to be rich in fiber, minerals (potassium, calcium, magnesium, iron, and sodium), and vitamins (B2, B6, and B12) and lower in energy, sugar, and fat. Ten different phenolic compounds were characterized. Naringenin, procyanidin C1, epicatechin, and rutin were the more abundant compounds in LLE. The administration of the LLE dose-dependently ameliorated hyperglycemia, insulin resistance, oxidative stress, and hyperlipidemia in HFG diet-fed mice. The median lethal dose of LLE was higher than 5000 mg/kg BW.

CONCLUSIONS

Loquat leaves are a potential source of micronutrients and polyphenols with beneficial effects on diabetes and its complications.

Chloroplast genome sequencing based on genome skimming for identification of Eriobotryae Folium

Background

Whole chloroplast genome (cpDNA) sequence is becoming widely used in the phylogenetic studies of plant and species identification, but in most cases the cpDNA were acquired from silica gel dried fresh leaves. So far few reports have been available to describe cpDNA acquisition from crude drugs derived from plant materials, the DNA of which usually was seriously damaged during their processing. In this study, we retrieved cpDNA from the commonly used crude drug Eriobotryae Folium (Pipaye in Chinese, which is the dried leaves of Eriobotrya japonica, PPY) using genome skimming technique.

Results

We successfully recovered cpDNA sequences and rDNA sequences from the crude drug PPY, and bioinformatics analysis showed a high overall consistency between the cpDNA obtained from the crude drugs and fresh samples. In the ML tree, each species formed distinct monophyletic clades based on cpDNA sequence data, while the phylogenetic relationships between Eriobotrya species were poorly resolved based on ITS and ITS2.

Conclusion

Our results demonstrate that both cpDNA and ITS/ITS2 are effective for identifying PPY and its counterfeits derived from distantly related species (i.e. Dillenia turbinata and Magnolia grandiflora), but cpDNA is more effective for distinguishing the counterfeits derived from the close relatives of Eriobotrya japonica, suggesting the potential of genome skimming for retrieving cpDNA from crude drugs used in Traditional Chinese Medicine for their identification.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12896-021-00728-0.

Cell suspension culture extract of Eriobotrya japonica attenuates growth and induces apoptosis in prostate cancer cells via targeting SREBP-1/FASN-driven metabolism and AR

BACKGROUND

Castration-resistant prostate cancer (CRPC) is one of the main causes of male cancer mortality. There is currently no effective treatment to cure this deadly prostate cancer (PCa) progression. However, recent research showed that activation of lipogenesis leads to CRPC progression. It provides a rationale to target the highly lipogenic activity as a novel and promising therapy against lethal CRPC.

PURPOSES

The present study aims to evaluate the anticancer efficacy and the molecular mechanism of cell suspension culture extract from Eriobotrya japonica (EJCE) in PCa, including CRPC.

METHODS

Cell growth, migration and invasion analyses were performed by MTT method, a wound healing assay and the transwell method, respectively. Apoptosis was assessed by a flow cytometry-based Annexin V-FITC/PI assay, caspase enzymatic activity and Western blot analyses. Lipogenesis was determined by a Fatty Acid Quantification Kit and an Oil Red O staining. The in vivo experiment was conducted by a xenograft mouse model.

RESULTS

PCa cell growth, migration and invasion were significantly affected by EJCE. EJCE decreased expression of sterol regulatory element-binding protein-1 (SREBP-1) and fatty acid synthase (FASN) in PCa cells, two main factors for lipogenesis. By inhibiting SREBP-1/FASN, EJCE reduced the intracellular fatty acid levels and lipid droplet accumulation in PCa. Moreover, EJCE down-regulated the androgen receptor (AR) and prostate-specific antigen (PSA) in PCa cells. Significantly, EJCE exhibited the potential anticancer activity by suppressing the growth and leading to apoptosis of CRPC tumors in a xenograft mouse model.

CONCLUSION

These results reveal a novel therapeutic molecular mechanism of EJCE in PCa. Blockade of SREBP-1/FASN-driven metabolism and AR by EJCE could be employed as a potent opportunity to cure malignant PCa.

Structure features, selenylation modification, and improved anti-tumor activity of a polysaccharide from Eriobotrya japonica

A homogeneous polysaccharide, EJP90-1, was isolated from the leaves of E. japonica by hot water extraction in this study. EJP90-1 (7702 Da) was a heteropolysaccharide mainly consisting of →5)-linked-α-L-Araf-(1→, →4)-linked-β-D-Manp-(1→, →2,4)-linked-α-L-Rhap-(1→, →4)-linked-α-D-Xylp-(1→, →4)-linked-β-D-Galp-(1→, →2)-linked-β-D-Galp-(1→, →6)-linked-β-D-Glcp-(1→, α-D-Glcp-(4→, and t-linked-α-L-Araf. EJP90-1 was found to show moderate anti-tumor activity at the cellular level. In order to improve the anti-tumor activity and the potential applications of EJP90-1, a typical sodium selenite-nitric acid (Na₂SeO₃-HNO₃) modification on EJP90-1 was carried out. X-ray photoelectron spectroscopy (XPS) and energy dispersive spectrometer (EDS) analysis confirmed that Se was successfully introduced into the polymer chain of EJP90-1. The subsequent in vitro cytotoxicity evaluation showed the selenylation modification derivative (EJP90-1-Se) possessed significant antiproliferative activity against cancer cells (HepG2 and A549 cells) through inducing cell apoptosis. The anti-tumor activity of EJP90-1-Se was further confirmed by zebrafish models, which inhibited the proliferation and migration of HepG2 cells and the angiogenesis.

Synthesis of deuterium-labeled cinnamic acids: Understanding the volatile benzenoid pathway in the flowers of the Japanese loquat Eriobotrya japonica

Cinnamic acids are widely distributed in plants, including crops for human use, and exhibit a variety of activities that are beneficial to human health. They also occupy a pivotal position in the biosynthesis of phenylpropanoids such as lignins, anthocyanins, flavonoids, and coumarins. In this context, deuterium-labeled cinnamic acids have been used as tracers and internal standards in food and medicinal chemistry as well as plant biochemistry. Therefore, a concise synthesis of deuterium-labeled cinnamic acids would be highly desirable. In this study, we synthesized deuterium-labeled cinnamic acids using readily available deuterium sources. We also investigated a hydrogen-deuterium exchange reaction in an ethanol-d₁ /Et₃ N system. This method can introduce deuterium atoms at the ortho and para positions of the phenolic hydroxy groups as well as at the C-2 position of alkyl cinnamates and is applicable to various phenolic compounds. Using the synthesized labeled compounds, we demonstrated that the benzenoid volatiles, such as 4-methoxybenzaldehyde, in the scent of the flowers of the Japanese loquat Eriobotrya japonica are biosynthesized from phenylalanine via cinnamic and 4-coumaric acids. This study provides easy access to a variety of deuterium-labeled (poly)phenols, as well as to useful tools for studies of the metabolism of cinnamic acids in living systems.

A WRKY Transcription Factor, EjWRKY17, from Eriobotrya japonica Enhances Drought Tolerance in Transgenic Arabidopsis

The WRKY gene family, which is one of the largest transcription factor (TF) families, plays an important role in numerous aspects of plant growth and development, especially in various stress responses. However, the functional roles of the WRKY gene family in loquat are relatively unknown. In this study, a novel WRKY gene, EjWRKY17, was characterized from Eriobotrya japonica, which was significantly upregulated in leaves by melatonin treatment during drought stress. The EjWRKY17 protein, belonging to group II of the WRKY family, was localized in the nucleus. The results indicated that overexpression of EjWRKY17 increased cotyledon greening and root elongation in transgenic Arabidopsis lines under abscisic acid (ABA) treatment. Meanwhile, overexpression of EjWRKY17 led to enhanced drought tolerance in transgenic lines, which was supported by the lower water loss, limited electrolyte leakage, and lower levels of reactive oxygen species (ROS) and malondialdehyde (MDA). Further investigations showed that overexpression of EjWRKY17 promoted ABA-mediated stomatal closure and remarkably up-regulated ABA biosynthesis and stress-related gene expression in transgenic lines under drought stress. Overall, our findings reveal that EjWRKY17 possibly acts as a positive regulator in ABA-regulated drought tolerance.

Preparative separation of structural isomeric pentacyclic triterpenes from Eriobotrya japonica (Thunb.) leaves by high speed countercurrent chromatography with hydroxypropyl-β-cyclodextrin as additive

Maslinic acid and corosolic acid with high purity were successfully separated from Eriobotrya japonica (Thunb.) leaves by two-step countercurrent chromatographic separation. Two biphasic solvent systems composed of petroleum ether-ethyl acetate-ethanol-water (6:4:5:5, v/v) and petroleum ether-ethyl acetate-ethanol-0.10 mol/L of hydroxypropyl-β-cyclodextrin with pH 7.0 (8:2:3.5:6.5, v/v) were selected according to the partition performance of the main structural isomeric pentacyclic triterpenes. The influences of pH value and concentration of hydroxypropyl-β-cyclodextrin in separation of two isomers were investigated. In first step countercurrent chromatographic separation, a mixture of two target structural isomers (14.12 mg of sample I) was separated from 40.00 mg of a partially purified sample. In second step countercurrent chromatographic separation, maslinic acid and corosolic acid were completely isolated from 12.00 mg of sample I with hydroxypropyl-β-cyclodextrin as aqueous phase additive. The recoveries of the two isomers were over 90%, yielding 5.18 mg of maslinic acid and 5.47 mg of corosolic acid, respectively.

Effects of native pollinator communities on the physiological and chemical parameters of loquat tree (Eriobotrya japonica) under open field condition

Wild and managed pollinators are the key component of biodiversity, contributing to important ecosystem services such as pollination and supporting human food security. Pollination by insects is a crucial component of the food chain that ensures the production of fruits and strongly affects the fruit quality, but the effect of insect pollination on fruit physiological and chemical parameters is largely unknown. The current study was conducted to determine the insect pollinators diversity and their relative abundance in the loquat (Eriobotrya japonica) orchard during 2017–2019. Further, the effect of insect pollinators pollination on the physiological and chemical parameters of fruit quality as compared to control pollinated flowers was investigated. The results revealed that a total of 22 species from 3 families (Apidae, Halictidae, and Syrphidae) were identified during the flowering season. The Apidae and Syrphidae were the most frequently observed families with major groups honey bees (67.89%) and hoverflies (21.57%), respectively. Moreover, results indicated that the fruit yield by the open-pollinated flowers (22.31 ± 0.34 kg/tree) was significantly higher than the control pollinated flowers (14.80 ± 0.25 kg/tree). Physiological and chemical parameters of loquat fruit differed significantly when fruits obtained from open-pollinated flowers as compared to control pollinated flowers. These results suggested that native insect pollinators play important role in the fruit quality of loquat. Hence, maintenance of appropriate habitat of native pollinators near loquat orchards is necessary to ensure good productivity and fruit quality.

Phlebopus roseus, a new edible bolete from China, is associated with insects and plants

Phlebopus roseus is described as new based on collections from southwest China. Phylogenetic analyses of nuclear rDNA internal transcribed spacer region ITS1-5.8S-ITS2 (ITS) and portions of nuclear 28S rDNA (28S), translation elongation factor 1-alpha (tef1), and the largest and second largest subunits of RNA polymerase II (rpb1, rpb2) support P. roseus as a novel species in the genus Phlebopus (Boletinellaceae, Boletales). The new species resembles P. portentosus but differs from it in that mature basidiomata have a bright rose-red-colored stipe and a radiate tubular hymenophore with nested pores. Despite extensive searching, P. roseus has only been found at four sites within a 24-hectare orchard dominated by Eriobotrya japonica, which is agriculturally important given its fruit production (loquats). Therefore, this species appears to be endemic and geographically restricted. The ecology of this bolete is also unique. In line with the trophic behavior of other species in the Boletinellaceae, our observations indicate that P. roseus forms a symbiotic association with the scale insect Coccus hesperidum, identified through sequence analysis of its mitochondrial cytochrome c oxidase subunit I (COI) region, to form fungus-insect galls that develop on roots of E. japonica trees. Phlebopus roseus is an edible mushroom species and is collected from the type location by farmers and sold commercially in limited quantities at local markets alongside P. portentosus and other fungi.

Dissection of the incidence and severity of purple spot physiological disorder in loquat fruit through a physiological and molecular approach

Loquat (Eriobotrya japonica) fruit marketability is affected by the incidence and severity of purple spot (PS), a pre-harvest physiological disorder showing an evident skin discoloration with depressed surface. Despite its impact in limiting the cultivation and economic potential of loquat, the etiology of this disorder is still poorly understood. To this end, our study aimed to investigate and disclose possible mechanisms underlying PS development. The intensity and severity of PS in three loquat cultivars ('Morphitiki', 'Karantoki' and 'Obusa') was phenotypically monitored during successive on-tree fruit developmental stages. 'Obusa' fruits harvested at commercial maturity stage showed the highest incidence of purple spot (58.6%), while 'Morphitiki' fruits did not show any symptoms. 'Karantoki' fruits demonstrated an intermediate response, with 31.3% of the fruit being affected. Thereafter, fruits with 30-50% PS severity were selected and used for further analysis; peel tissue was removed from both symptomatic and asymptomatic tissue of the same fruit for all examined cultivars. 'Karantoki' fruit with PS were characterized by the highest accumulation of total soluble sugars, sucrose, glucose and fructose contents, while the concentration of these primary metabolites was the lowest in asymptomatic fruit of 'Obusa', exception made for the sucrose. The incidence of PS was also transcriptionally investigated by assessing the mRNA profile of important genes involved in polyphenolic (PAL1, PAL2 and PPO1) and carbohydrate (CWI2, CWI3, SPS1, SPS2, NI2, NI3, SuSy, HXK, FRK and VI) pathway. The enhanced expression levels of CWI3 and VI genes in symptomatic fruit of the highly susceptible cultivar 'Obusa' highlight a cultivar-specific type of response. Notably, SuSy registered significantly suppressed levels in symptomatic tissue of both 'Obusa' and 'Karantoki'. To what extent PPO is associated with PS incidence and whether the etiology of the disorder can be assigned to an oxidative process triggered and coordinated by its action need to be further elucidated. The aforementioned genes are suggested to be further examined as potential markers towards a more sophisticated and informed characterization of purple spot detection in loquat fruit.

An Integrative Analysis of Transcriptome, Proteome and Hormones Reveals Key Differentially Expressed Genes and Metabolic Pathways Involved in Flower Development in Loquat

Flower development is a vital developmental process in the life cycle of woody perennials, especially fruit trees. Herein, we used transcriptomic, proteomic, and hormone analyses to investigate the key candidate genes/proteins in loquat (Eriobotrya japonica) at the stages of flower bud differentiation (FBD), floral bud elongation (FBE), and floral anthesis (FA). Comparative transcriptome analysis showed that differentially expressed genes (DEGs) were mainly enriched in metabolic pathways of hormone signal transduction and starch and sucrose metabolism. Importantly, the DEGs of hormone signal transduction were significantly involved in the signaling pathways of auxin, gibberellins (GAs), cytokinin, ethylene, abscisic acid (ABA), jasmonic acid, and salicylic acid. Meanwhile, key floral integrator genes FLOWERING LOCUS T (FT) and SUPPRESSOR OF OVEREXPRESSION OF CONSTANS1 (SOC1) and floral meristem identity genes SQUAMOSA PROMOTER BINDING LIKE (SPL), LEAFY (LFY), APETALA1 (AP1), and AP2 were significantly upregulated at the FBD stage. However, key floral organ identity genes AGAMOUS (AG), AP3, and PISTILLATA (PI) were significantly upregulated at the stages of FBE and FA. Furthermore, transcription factors (TFs) such as bHLH (basic helix-loop-helix), NAC (no apical meristem (NAM), Arabidopsis transcription activation factor (ATAF1/2) and cup-shaped cotyledon (CUC2)), MYB_related (myeloblastosis_related), ERF (ethylene response factor), and C2H2 (cysteine-2/histidine-2) were also significantly differentially expressed. Accordingly, comparative proteomic analysis of differentially accumulated proteins (DAPs) and combined enrichment of DEGs and DAPs showed that starch and sucrose metabolism was also significantly enriched. Concentrations of GA3 and zeatin were high before the FA stage, but ABA concentration remained high at the FA stage. Our results provide abundant sequence resources for clarifying the underlying mechanisms of the flower development in loquat.

Evolution of Carotenoids, Sensory Profiles and Volatile Compounds in Microwave-Dried Fruits of Three Different Loquat Cultivars (Eriobotrya japonica Lindl.)

The consumption of loquat fruits is highly appreciated for their carotenoid content and valuable sensory notes, but it is limited due to the low shelf-life. An on-line temperature controlled microwave system based on infrared thermography was used to dry three different loquat cultivar at 60 °C. The time to reach the target value of 23% moisture content was about 105 min in Claudia fruits and 162 min in Virticchiara and Peluche. Seven carotenoids were identified in loquat fruits, among these the major were all-trans-β-carotene in Virticchiara and Claudia. Virticchiara had the major total carotenoid content (206 μg/g dry basis), followed by Peluche (158 μg/g d.b.) and Claudia (41 μg/g d.b.). The loss of carotenoids after drying ranged between 24% (Peluche) and 41% (Claudia). Carotenoids that showed a higher loss were on average: lutein (70%) and zeaxhantin (51%). Thirty-five volatile compounds were identified in fresh and dried loquats: the aldehydes were the most abundant class. After drying, aldehydes declined slightly, with alcohols falling more sharply. The shortened times by using temperature-controlled microwave heating with infrared thermography have guaranteed a fair quality of the dried loquats from the nutritional and sensory point of view, variable among the three cultivars.

Identification of key taste components in loquat using widely targeted metabolomics

Loquats can be divided into white- and yellow-fleshed cultivars. Generally, white-fleshed cultivars taste better than yellow-fleshed cultivars. Currently, metabolic causes of differences in taste are unknown, due to the lack of a large-scale and comprehensive investigation of metabolites in loquat fruit. Here, we performed a LC-MS/MS-based widely targeted metabolome analysis on two cultivars, 'Baiyu' (white-fleshed) and 'ZaozhongNo. 6' (yellow-fleshed). A total of 536 metabolites were identified, 193 of which (including 7 carbohydrates, 12 organic acids and 8 amino acids) were different between the cultivars. Pathway enrichment analysis also identified significant differences in phenolic pathways between the cultivars. Our results suggest that taste differences between the cultivars can be explained by variations in composition and abundance of carbohydrates, organic acids, amino acids, and phenolics. This study provides new insights into the underlying metabolic causes of taste variation in loquat.

Water Deficit Affects the Growth and Leaf Metabolite Composition of Young Loquat Plants

Water scarcity in the Mediterranean area is very common and understanding responses to drought is important for loquat management and production. The objective of this study was to evaluate the effect of drought on the growth and metabolism of loquat. Ninety two-year-old plants of 'Marchetto' loquat grafted on quince were grown in the greenhouse in 12-liter pots and three irrigation regimes were imposed starting on 11 May and lasting until 27 July, 2013. One-third of the plants was irrigated with 100% of the water consumed (well watered, WW), a second group of plants was irrigated with 66% of the water supplied to the WW plants (mild drought, MD), and a third group was irrigated with 33% of the water supplied to the WW plants (severe drought, SD). Minimum water potential levels of -2.0 MPa were recorded in SD plants at the end of May. Photosynthetic rates were reduced according to water supply (WW>MD>SD), especially during the morning hours. By the end of the trial, severe drought reduced all growth parameters and particularly leaf growth. Drought induced early accumulation of sorbitol in leaves, whereas other carbohydrates were not affected. Of over 100 leaf metabolites investigated, 9 (squalene, pelargonic acid, glucose-1-phosphate, palatinol, capric acid, aconitic acid, xylitol, lauric acid, and alanine) were found to be useful to discriminate between the three irrigation groups, suggesting their involvement in loquat metabolism under drought conditions. Loquat behaved as a moderately drought-tolerant species (limited stem water potential and growth reductions) and the accumulation of sorbitol in favor of sucrose in mildly-stressed plants may be considered an early protective mechanism against leaf dehydration and a potential biochemical marker for precise irrigation management.

EjFRI, FRIGIDA (FRI) Ortholog from Eriobotrya japonica, Delays Flowering in Arabidopsis

In the model species Arabidopsis thaliana, FRIGIDA (FRI) is a key regulator of flowering time and can inhibit flowering without vernalization. However, little information is available on the function in the Rosaceae family. Loquat (Eriobotrya japonica) belongs to the family Rosaceae and is a distinctive species, in which flowering can be induced without vernalization, followed by blooming in late-autumn or winter. To investigate the functional roles of FRI orthologs in this non-vernalization species, we isolated an FRI ortholog, dubbed as EjFRI, from loquat. Analyses of the phylogenetic tree and protein sequence alignment showed that EjFRI is assigned to eurosids I FRI lineage. Expression analysis revealed that the highest expression level of EjFRI was after flower initiation. Meanwhile, EjFRI was widely expressed in different tissues. Subcellular localization of EjFRI was only detected to be in the nucleus. Ectopic expression of EjFRI in wild-type Arabidopsis delayed flowering time. The expression levels of EjFRI in transgenic wild-type Arabidopsis were significantly higher than those of nontransgenic wild-type lines. However, the expression levels of AtFRI showed no significant difference between transgenic and nontransgenic wild-type lines. Furthermore, the upregulated AtFLC expression in the transgenic lines indicated that EjFRI functioned similarly to the AtFRI of the model plant Arabidopsis. Our study provides a foundation to further explore the characterization of EjFRI, and also contributes to illuminating the molecular mechanism about flowering in loquat.

Expression Pattern and Functional Characterization of PISTILLATA Ortholog Associated With the Formation of Petaloid Sepals in Double-Flower Eriobotrya japonica (Rosaceae)

Double-flower Eriobotrya japonica, of which one phenotype is homeotic transformation of sepals into petals, is a new germplasm for revealing the molecular mechanisms underlying the floral organ transformation. Herein, we analyzed the sequence, expression pattern and functional characterization of EjPI, which encoded a B-class floral homeotic protein referred to as PISTILLATA ortholog, from genetically cognate single-flower and double-flower E. japonica. Phylogenetic analysis suggested that the EjPI gene was assigned to the rosids PI/GLO lineage. Analysis of protein sequence alignments showed that EjPI has typical domains of M, I, K, and C, and includes a distinctive PI motif at the C-terminal region. Compared with asterids PI/GLO lineage, the K1 and K3 subdomains of EjPI both contain a single amino acid difference. Subcellular localization of EjPI was determined to be in the nucleus. Expression pattern analysis revealed that EjPI expressed not only in petals, filament, and anther in single-flower E. japonica, but also in petaloid sepals in double-flower E. japonica. Meanwhile, there were high correlation between EjPI transcript level and petaloid area within a sepal. Furthermore, 35S::EjPI transgenic wild-type Arabidopsis caused the homeotic transformation of the first whorl sepals into petaloid sepals. Ectopic expression of EjPI in transgenic pi-1 mutant Arabidopsis rescued normal petals and stamens. These results suggest expression pattern of EjPI is associated with the formation of petaloid sepal. Our study provides the potential application of EjPI for biotechnical engineering to create petaloid sepals or regulate floral organ identity in angiosperms.

Comparison of structural characteristics and bioactivities of polysaccharides from loquat leaves prepared by different drying techniques

In the present study, freeze drying, hot-air drying, vacuum drying, and microwave drying at the microwave powers of 400, 600, and 800 W, respectively, were utilized to dry loquat leaves for evaluating the effects of different drying techniques on the physicochemical structures and bioactivities of polysaccharides extracted from loquat leaves (LLPs). Results demonstrated that the physicochemical structures and bioactivities of LLPs significantly affected by different drying techniques. The degrees of esterification, molar ratios of constituent monosaccharides, contents of uronic acids, apparent viscosities, and molecular weights of LLPs were varied by different drying techniques. Additionally, LLPs, particularly LLP-M4 which extracted from loquat leaves prepared by microwave drying at the power of 400 W, exerted remarkable in vitro binding capacities, strong inhibitory effects on α-amylase and α-glucosidase, and obvious antioxidant activities. Results indicated that the microwave drying could be an efficient drying technique before extraction of bioactive LLPs, and LLPs had great potential applications in the functional food and pharmaceutical industries.

Phylogenetic relationships and characterization of the complete mitochondrial genome of Eriobotrya japonica in southeast of China

Eriobotrya japonica is an evergreen fruit tree originating in southeastern China. Its fruit is juicy with a pleasant taste and considerable medical value. However, there is no complete mitochondrial (cmt) genome resource for this species. This is the first report of the cmt genome of Eriobotrya japonica from southeastern China. The whole cmt genome was 434,980 bp in size with 37.80% GC content. The cmt genome of Eriobotrya japonica contains 41 protein-coding genes, 22 tRNA genes, and 3 rRNA genes. A phylogenetic maximum-likelihood (ML) tree was constructed based on 22 mitochondrial genomes from plant species. Eriobotrya japonica grouped closely with other Rosaceae species, which provides strong support for the traditional classification.

Effects of Eriobotrya japonica Water Extract on Alcoholic and Nonalcoholic Fatty Liver Impairment

The aim of this study was to investigate the potential protective effects of the hot water extract of Eriobotrya japonica (EJW) on EtOH- or free fatty acid (FFA)-induced fatty liver injury in vitro. HepG2/2E1 cells were exposed to EtOH and HepG2 cells were exposed to a mixture of FFAs (oleic acid:palmitic acid, 2:1) to stimulate oxidative stress and to induce lipid accumulation, respectively. Antioxidant activity was significantly increased and lipid accumulation was inhibited in cells pretreated with EJW compared to those in cells exposed to EtOH or FFA only. Also, 5'adenosine monophosphate (AMP)-activated protein kinase (AMPK) and acetyl-coenzyme A carboxylase (ACC) phosphorylations were considerably increased, indicating activation of AMPK. Furthermore, EJW reduced the messenger RNA (mRNA) expression of lipogenesis-associated factors such as ACC, sterol regulatory element binding protein-1c (SREBP-1c), and fatty acid synthase (FAS), and increased mRNA expression related to components of the fatty acid β-oxidation pathway, such as AMPK, carnitine palmitoyltransferase 1 (CPT-1), and peroxisome proliferator-activated receptor alpha (PPARα). These results suggest that EJW possessed potential preventive effects against both EtOH- and FFA-induced fatty liver disease by alleviation of oxidative stress and lipid accumulation in hepatocytes.

Ectopic expression of an Eriobotrya japonica APETALA3 ortholog rescues the petal and stamen identities in Arabidopsis ap3-3 mutant

APETALA3: (AP3) encodes a floral homeotic class B-function MADS-box protein and plays crucial roles in petal and stamen development. To better understand the functional roles of AP3 orthologs in Eriobotrya, we isolated and identified an AP3 ortholog, referred to as EjAP3, from Eriobotrya japonica. Analyses of protein sequence and phylogenetic tree showed that the EjAP3 was assigned to the rosids euAP3 lineage and included a distinctive PI-derived and euAP3 motifs at the C-terminal domain. Subcellular localization of EjAP3 was determined to be in the nucleus. Expression analysis suggested that EjAP3 expression was restricted only in petals and stamens, but not in sepals and carpels. Importantly, during the floral development, EjAP3 expression level was the highest at the stage of visible floral bud. Furthermore, ectopic expression of EjAP3 in Arabidopsis ap3-3 mutant rescued the second whorl petals and the third whorl stamens. The expression pattern and function characterization of EjAP3 contribute to better understand the roles of AP3 orthologs in Eriobotrya.

Fatty Acid Composition and Applications of Eriobotrya japonica Seed Oil

The loquat (Eriobotrya japonica) is commonly found in Japan. Its fruits are consumed raw or used in processed foods, and its leaves are used as a traditional medicine and in the manufacturing of cosmetics. Additionally, its seeds have several industrial applications. Therefore, this study aimed to estimate the fatty acid composition of loquat seed oil, and to evaluate its potential application as a deodorant. Palmitic acid, linoleic acid, behenic acid, and lignoceric acid were found to be the primary fatty acids present in the seeds, among which linoleic acid was involved in the deodorization of allyl methyl sulfide. Based on these results, loquat seed oil has potential for use in deodorant production.

Green Biosynthesis of Silver Nanoparticles Using Eriobotrya japonica (Thunb.) Leaf Extract for Reductive Catalysis

This article reports on silver nanoparticles (AgNPs) that were green-synthesized by using Eriobotrya japonica (Thunb.) leaf extract and their use for the catalytic degradation of reactive dyes. The properties of biogenic AgNPs were characterized using UV-vis absorption spectroscopy, field emission scanning electron microscope (FESEM), X-ray powder diffraction (XRD), transmission electron microscope (TEM), Fourier transforming infrared spectroscopy (FTIR), energy dispersive X-ray spectroscopy (EDS), and selected area electron diffraction (SAED) analysis. The UV-vis spectroscopy and X-ray analyses confirmed the formation of AgNPs and showed the strong absorbance around 467 nm with surface plasmon resonance (SPR). The mean diameter of biogenic AgNPs at room (20 °C), moderate (50 °C), and high temperatures (80 °C) were 9.26 ± 2.72, 13.09 ± 3.66, and 17.28 ± 5.78 nm, respectively. The reaction temperature had significant impacts on the sizes of synthesized AgNPs. The higher the synthesis temperature, the larger size and the lower catalysis activity for reductive decomposition of reactive dyes via NaBH₄. The results supported a bio-green approach for developing AgNPs with a small size and stable degradation activity of reactive dyes over 92% in 30 min by using Eriobotrya japonica (Thunb.) leaf extract at pH 7, 20 °C, and 1:10 ratio of silver nitrate added to the leaf extract.

Anti-Apoptosis and Anti-Fibrosis Effects of Eriobotrya Japonica in Spontaneously Hypertensive Rat Hearts

Myocardial apoptosis and fibrosis represent important contributing factors for development of hypertension-induced heart failure. The present study aims to investigate the potential effects of Eriobotrya japonica leaf extract (EJLE) against hypertension-induced cardiac apoptosis and fibrosis in spontaneously hypertensive rats (SHRs). Twelve-week-old male rats were randomly divided into four different groups; control Wistar Kyoto (WKY) rats, hypertensive SHR rats, SHR rats treated with a low dose (100 mg/kg body weight) of EJLE and SHR rats treated with a high dose (300 mg/kg body weight) of EJLE. Animals were acclimatized for 4 weeks and thereafter were gastric fed for 8 weeks with two doses of EJLE per week. The rats were then euthanized following cardiac functional analysis by echocardiography. The cardiac tissue sections were examined by Terminal Deoxynucleotidyl Transferase-Mediated Deoxyuridine Triphosphate (dUTP) Nick End-Labeling (TUNEL) assay, histological staining and Western blotting to assess the cardio-protective effects of EJ in SHR animals. Echocardiographic measurements provided convincing evidence to support the ability of EJ to ameliorate crucial cardiac functional characteristics. Furthermore, our results reveal that supplementation of EJLE effectively attenuated cardiac apoptosis and fibrosis and also enhanced cell survival in hypertensive SHR hearts. Thus, the present study concludes that EJLE potentially provides cardio-protective effects against hypertension-induced cardiac apoptosis and fibrosis in SHR animals.

Bioactive triterpenoids from the leaves of Eriobotrya japonica as the natural PDE4 inhibitors

The ethanolic extract of the leaves of Eriobotrya japonica exhibited inhibitory activity against phosphodiesterase-4D (PDE4D), which is a therapeutic target of inflammatory disease. Subsequent bioassay-guided fractionation led to the isolation of a new triterpene (1), together with seven known triterpenoids, methyl corosolate (2), ursolic acid (3), oleanolic acid (4), methyl maslinate (5), α-amyin (6), 3β,19α,23-trihydroxy-urs-12-ene (7) and uvaol (8). The structure of compound 1 was established as 3β-hydroxyl-21β-acetoxyl-urs-12-en-28-carboxylate on the basis of interpretation of its 1D and 2D NMR and HR-ESI-MS spectroscopic data. The bioassay results verified compounds 2, 3 and 8 inhibited PDE4D2 effectively with the IC50 values of 3.06, 2.18 and 5.17 μM, respectively, which may provide a novel mechanism for the anti-inflammatory activity of the leaves of E. japonica.

Metabolic and transcriptional elucidation of the carotenoid biosynthesis pathway in peel and flesh tissue of loquat fruit during on-tree development

BACKGROUND

Carotenoids are the main colouring substances found in orange-fleshed loquat fruits. The aim of this study was to unravel the carotenoid biosynthetic pathway of loquat fruit (cv. 'Obusa') in peel and flesh tissue during distinct on-tree developmental stages through a targeted analytical and molecular approach.

RESULTS

Substantial changes regarding colour parameters, both between peel and flesh and among the different developmental stages, were monitored, concomitant with a significant increment in carotenoid content. Key genes and individual compounds that are implicated in the carotenoid biosynthetic pathway were further dissected with the employment of molecular (RT-qPCR) and advanced analytical techniques (LC-MS). Results revealed significant differences in carotenoid composition between peel and flesh. Thirty-two carotenoids were found in the peel, while only eighteen carotenoids were identified in the flesh. Trans-lutein and trans-β-carotene were the major carotenoids in the peel; the content of the former decreased with the progress of ripening, while the latter registered a 7.2-fold increase. However, carotenoid profiling of loquat flesh indicated trans-β-cryptoxanthin, followed by trans-β-carotene and 5,8-epoxy-β-carotene to be the most predominant carotenoids. High amounts of trans-β-carotene in both tissues were supported by significant induction in a chromoplast-specific lycopene β-cyclase (CYCB) transcript levels. PSY1, ZDS, CYCB and BCH were up-regulated and CRTISO, LCYE, ECH and VDE were down-regulated in most of the developmental stages compared with the immature stage in both peel and flesh tissue. Overall, differential regulation of expression levels with the progress of on-tree fruit development was more evident in the middle and downstream genes of carotenoid biosynthetic pathway.

CONCLUSIONS

Carotenoid composition is greatly affected during on-tree loquat development with striking differences between peel and flesh tissue. A link between gene up- or down-regulation during the developmental stages of the loquat fruit, and how their expression affects carotenoid content per tissue (peel or flesh) was established.

The Potential of Triterpenoids from Loquat Leaves (Eriobotrya japonica) for Prevention and Treatment of Skin Disorder

The leaves of loquat (Eriobotrya japonica) possess high medicinal value and have been used as traditional medicines. However, there are no evidence-based studies on the skin-care effects of E. japonica leaves. To explore new biological activities of E. japonica leaves against skin disorder and to gain a better understanding of the chemical components associated with bioactivities, we evaluated 18 triterpenoids from E. japonica leaves on anti-melanogenesis, anti-acne, anti-allergy and anti-aging activities. Our results revealed that eight compounds showed anti-melanogenesis activity, of which ursolic acid (1) and maslinic acid (7) were the most potent with the similar selective index to that of arbutin. Structure–activity relationship and possible mechanism of active compounds were proposed. Twelve compounds exhibited anti-acne effect; ursolic acid (1), maslinic acid (7), corosolic acid (8) and euscaphic acid (12) showed highest activities against P. acnes. Four compounds displayed anti-allergy and anti-inflammatory activity; 3-epicorosolic acid (9) and euscaphic acid (12) showed marked activity against β-hexosaminidase release. Finally, ursolic acid (1), pomolic acid (10), colosolic acid (8) and its methylated derivative (6) exhibited the highest anti-aging activity by stimulating collagen and hyaluronic acid (HA) production. Our findings provide valuable evidence that E. japonica leaves have potential applications as ingredients of function foods or cosmetics for health benefits and a number of triterpenoids may play an important role in these bioactivities.

Footprints of domestication revealed by RAD-tag resequencing in loquat: SNP data reveals a non-significant domestication bottleneck and a single domestication event

Background

The process of crop domestication has long been a major area of research to gain insights into the history of human civilization and to understand the process of evolution. Loquat (Eriobotrya japonica Lindl.) is one of the typical subtropical fruit trees, which was domesticated in China at least 2000 years ago. In the present study, we re-sequenced the genome of nine wild loquat accessions collected from wide geographical range and 10 representative cultivated loquat cultivars by using RAD-tag tacit to exploit the molecular footprints of domestication.

Results

We obtained 26.4 Gb clean sequencing data from 19 loquat accessions, with an average of 32.64 M reads per genotype. We identified more than 80,000 SNPs distributed throughout the loquat genome. The SNP density and numbers were slightly higher in the wild loquat populations than that in the cultivated populations. All cultivars were clustered together by structure, phylogenetic and PCA analyses.

Conclusion

The modern loquat cultivars have experienced a non-significant genetic bottleneck during domestication, and originated from a single domesticated event. Moreover, our study revealed that Hubei province of China is probably the origin center of cultivated loquat.

Electronic supplementary material

The online version of this article (doi:10.1186/s12864-017-3738-y) contains supplementary material, which is available to authorized users.

Changes in soluble sugar metabolism in loquat fruit during different cold storage

To investigate soluble sugar metabolism and its relationship to chilling injury (CI), loquat fruits were stored at 0 and 5 °C for 5 weeks. CI symptoms were monitored during storage, and soluble sugar content and related enzyme activities were measured. Enzymes activities and substrate levels in the ascorbate-glutathione (AsA-GSH) cycle were also determined. Fruit at 0 °C had lower sucrose levels and higher levels of glucose and fructose than fruit maintained at 5 °C, and also manifested less severe CI symptoms. Fruit at 0 °C also exhibited increased activities of acid invertase, neutral invertase, sucrose phosphatesynthase and sucrose synthase. AsA-GSH cycle activity at 0 °C was much higher than that at 5 °C. Glucose levels correlated positively with levels of AsA and GSH and ascorbate peroxidase (APX) activity. The increased glucose levels are sufficient to account for the chilling tolerance of loquat fruit.

Comparative Transcriptional Analysis of Loquat Fruit Identifies Major Signal Networks Involved in Fruit Development and Ripening Process

Loquat (Eriobotrya japonica Lindl.) is an important non-climacteric fruit and rich in essential nutrients such as minerals and carotenoids. During fruit development and ripening, thousands of the differentially expressed genes (DEGs) from various metabolic pathways cause a series of physiological and biochemical changes. To better understand the underlying mechanism of fruit development, the Solexa/Illumina RNA-seq high-throughput sequencing was used to evaluate the global changes of gene transcription levels. More than 51,610,234 high quality reads from ten runs of fruit development were sequenced and assembled into 48,838 unigenes. Among 3256 DEGs, 2304 unigenes could be annotated to the Gene Ontology database. These DEGs were distributed into 119 pathways described in the Kyoto Encyclopedia of Genes and Genomes (KEGG) database. A large number of DEGs were involved in carbohydrate metabolism, hormone signaling, and cell-wall degradation. The real-time reverse transcription (qRT)-PCR analyses revealed that several genes related to cell expansion, auxin signaling and ethylene response were differentially expressed during fruit development. Other members of transcription factor families were also identified. There were 952 DEGs considered as novel genes with no annotation in any databases. These unigenes will serve as an invaluable genetic resource for loquat molecular breeding and postharvest storage.

Induced parthenogenesis by gamma-irradiated pollen in loquat for haploid production

Successful haploid induction in loquat (Eriobotrya japonica (Thunb.) Lindl.) through in situ-induced parthenogenesis with gamma-ray irradiated pollen has been achieved. Female flowers of cultivar 'Algerie' were pollinated using pollen of cultivars 'Changhong-3', 'Cox' and 'Saval Brasil' irradiated with two doses of gamma rays, 150 and 300 Gy. The fruits were harvested 90, 105 and 120 days after pollination (dap). Four haploid plants were obtained from 'Algerie' pollinated with 300-Gy-treated pollen of 'Saval Brasil' from fruits harvested 105 dap. Haploidy was confirmed by flow cytometry and chromosome count. The haploids showed a very weak development compared to the diploid plants. This result suggests that irradiated pollen can be used to obtain parthenogenetic haploids.

Characterization of an O-methyltransferase specific to guaiacol-type benzenoids from the flowers of loquat (Eriobotrya japonica)

Volatile benzenoids, including methyl p-methoxybenzoate, p-anisaldehyde, and p-anisalcohol, are responsible for the sweet and characteristic fragrance of loquat (Eriobotrya japonica, Rosaceae) flowers. Although the full pathway of volatile benzenoid synthesis has yet to be elucidated, their chemical structures suggest that O-methyltransferases are present in loquat and function in the methylation of the para-OH groups. In the present study, we used RNA-sequencing to identify four loquat genes (EjOMT1, EjOMT2, EjOMT3, and EjOMT4) that encode O-methyltransferases. We found that EjOMT1 was highly expressed in floral tissues, with an expression pattern that coincided with changes in intracellular volatile benzenoids during flower development. Recombinant EjOMT1 protein expressed in Escherichia coli showed the highest activity towards guaiacol with a K_m value of 35 μM. Furthermore, the protein also showed lesser activities towards guaiacol-type benzenoids including eugenol, isoeugenol, vanillin, and ferulic acid, in addition to much weaker activities towards catechol and p-hydroxybenzenoid derivatives. However, no activity was shown towards phenylpropenes without m-methoxy substitution, t-anol and chavicol. Taken together, our findings indicate that EjOMT1 has a broad substrate specificity towards compounds with both para-OH and meta-OCH₃ groups, unlike previously characterized O-methyltransferases for volatile benzenoid/phenylpropanoid biosynthesis.

Eriobotrya japonica seed biocomposite efficiency for copper adsorption: Isotherms, kinetics, thermodynamic and desorption studies

Adsorption techniques are widely used to remove pollutants from wastewater; however, composites are gaining more importance due to their excellent adsorption properties. Bentonite composite with Eriobotrya japonica seed was prepared and used for the adsorption of copper (Cu) metal from aqueous media. The process variables such as pH, Cu(II) ions initial concentration, adsorbent dose, contact time and temperature were optimized for maximum Cu(II) adsorption. At pH 5, adsorbent dose 0.1 g, contact time 45 min, Cu(II) ions initial concentration 75 mg/L and temperature 45 °C, maximum Cu(II) adsorption was achieved. Desorption studies revealed that biocomposite is recyclable. Langmuir, Freundlich and Harkins-Jura isotherms as well as pseudo-first and pseudo-second-order kinetics models were applied to understand the adsorption mechanism. Thermodynamic parameters (ΔG(0), ΔH(0) and ΔS(0)) suggest that the adsorption process was spontaneous and endothermic in nature. The pseudo-second-order kinetic model and Langmuir isotherm fitted well to the adsorption data. Results showed that biocomposite was more efficient for Cu(II) adsorption in comparison to individuals native Eriobotrya japonica seed biomass and Na-bentonite.

Eriobotrya japonica Water Extract Characterization: An Inducer of Interferon-Gamma Production Mainly by the JAK-STAT Pathway

Eriobotrya japonica (Thunb.) Lindl. (Loquat) (EJ) has been used as a medicinal plant to treat chronic bronchitis, coughs, phlegm, high fever and gastro-enteric disorders. Since the traditional use of EJ is related to modulating inflammation processes, our earlier studies on EJ leaves were performed on the water extract to investigate specific cytokines’ modulation. These earlier studies, however, have shown that EJ leaf water extract (WE) and the water phase (WP) induce cytokines’ production in in vitro and in vivo models. Therefore, the aim of this study was to specify the group(s) of compounds in EJ leaves that have this immunomodulatory activity and their mechanism of action. WE was obtained from boiling the leaves followed by butanol extraction, yielding a butanol-water phase (WP). WP was then subjected to methanol:acetone fractionation, yielding upper (MAU) and lower (MAL) phases. For further fractionation, MAU was subjected to column chromatography followed by elution with ethanol:water (EW), methanol:ethanol (ME) and, lastly, acetone:water (AW), respectively, to reveal three sub-fractions; MAU-EW, MAU-ME and MAU-AW. MAU-AW significantly increased IFN-γ production from unstimulated and stimulated mouse spleen cells, as well as CD3+ T cells and natural killer cells. Furthermore, the fold increase of IFN-γ production by MAU-AW was concentration dependent, higher than the parent extract or any of the other sub-fractions, and such an IFN-γ increase was reversed by two JAK-STAT inhibitors. In addition, MALDI-TOF-MS analysis of the extracts and sub-fractions showed compounds with molecular weights of >500 Daltons. The MAU-AW sub-fraction contained more polar compounds, such as flavonol and caffeic glycosides. In conclusion, these polar compounds in the EJ extract are responsible for inducing IFN-γ production. Further chemical elucidation is warranted to lead to a specific IFN-γ inducer and an immunomodulator in polarizing immune cells and balancing immune responses in certain diseases.

Evaluation of antioxidant activity of loquat fruit (Eriobotrya japonica lindl.) skin and the feasibility of their application to improve the oxidative stability of soybean oil

The effects of ultrasound-assisted, supercritical CO2 and solvent extraction techniques on antioxidant activity of loqua (Eriobotrya japonica Lindl.) skin extract in oxidation stability of soybean oil was evaluated. The antioxidant efficacy of extracts was determined using 2, 2-diphenyl-1-picrylhydrazyl (DPPH(•)) radical scavenging capacity, β-carotene/linoleic acid, and Rancimat test system. Results showed that solvent extract of loquat fruit skin at 400 ppm had the highest antioxidant activity compared to ultrasound-assisted and supercritical CO2 extracts. Further, solvent extraction was the most effective method for extraction of phenolic compounds. Protective effects of extracts in stabilization of soybean oil during both frying and storage conditions were tested and compared to tert-butyl hydroquinone (TBHQ) by measuring their peroxide value, free fatty acids, conjugated dienes and trienes value. During frying process solvent extract of skin at 400 ppm (SOEA) exhibited stronger antioxidant activity in oil compared to other oil samples, but this antioxidant potential was lower than TBHQ in storage conditions. Present study showed that loquat fruit skin is a good source of natural antioxidant compounds, and has the potential to be used as a substitute for synthetic antioxidants in vegetable oils.

Anti-inflammatory and antioxidant properties of Eriobotrya japonica leaves extracts

BACKGROUND

In the present work we determined phenolic and flavonoids content of Eriobotrya japonica leaves extracts and fractions and their antioxidant and anti-inflammatory properties.

OBJECTIVES

To evaluate the inhibition of inflammatory PLA2 and antioxidant effects of extracts and fractions from Eriobotrya japonica leaves.

METHODS

Antioxidant activity was evaluated with DPPH radical scavenging assay and anti-inflammatory effect of fractions was measured by their inhibition potency on the human pro-inflammatory phospholipase A2 (group IIA).

RESULTS

The EtOH/EtOAc 2:1 extract exhibited a potent inhibition of the hG-IIA with an IC50 values of 8 µg/ml. It also shows an antioxidant activity measured on DPPH with an IC50 of 42 µg/ml. Fractionation shows that CH2Cl2/MeOH 0:1 fraction was the rich one on flavonoids compounds (4.3 mg/g dry weight) and demonstrates a high antioxidant activity with an IC50 of 12 µg/ml. The anti-inflammatory evaluation demonstrates that the same fraction was the best one to inhibit the pro-inflammatory phospholipase A2 group IIA with an IC50 of 4 µg/ml.

CONCLUSION

Study conducted on Eriobotrya japonica shows that CH2Cl2/MeOH 0:1 fraction inhibits efficiently the hG-IIA phospholipase. which is considered as pro-inflammatory enzyme.

Influence of extraction techniques on antioxidant properties and bioactive compounds of loquat fruit (Eriobotrya japonica Lindl.) skin and pulp extracts

In this study, the bioactive compounds of loquat fruit (Eriobotrya japonica Lindl.) skin and pulp extracted by two extraction methods (solvent and ultrasound-assisted) with three solvents (ethanol, water and ethanol-water) were compared to supercritical fluid extraction. The antioxidant activities of skin and pulp extracts were evaluated and compared to tertiary butylhydroquinone (TBHQ) using 2, 2-diphenyl-1-picrylhydrazyl (DPPH˙) radical scavenging, β-carotene bleaching, and the Rancimat assays. In DPPH assay solvent extracts of skin by ethanol (SSE) and ethanol-water (SSEW) showed strong inhibitory activity. The SSEW also showed the highest inhibition percentage of 85.58% by the β-carotene bleaching assay and longest induction time of 4.78 h by the Rancimat method. The large amount of tocopherols and phenolics contained in the skin extract may cause its strong antioxidant ability. The results indicated that the solvent extraction with ethanol-water produced the maximum extraction yield of phenolic and tocopherol compounds from loquat fruit skin and pulp. Furthermore, solvent extraction was the most effective in antioxidant activity of the extracts compared to other extraction techniques.

A structure-activity relationship study on antiosteoclastogenesis effect of triterpenoids from the leaves of loquat (Eriobotrya japonica)

Our previous results elucidated that the leaves of Eriobotrya japonica possessed the potential to suppress ovariectomy-induced bone mineral density deterioration, and ursolic acid, the major bioactive component in these leaves, suppressed the osteoclast differentiation. The aim of this study was to discover more candidates for development of novel antiosteoclastogenesis agents from the leaves of E. japonica. Phytochemical analysis following a cell-based osteoclastic tartrate-resistant acid phosphatase (TRAP) activity assay revealed 11 more compounds with a potent antiosteoclastogenesis effect. The potency of ursane-type triterpenoids from the leaves of E. japonica prompted us to investigate the structure-activity relationships underlying their antiosteoclastogenesis. The results revealed that both the hydroxyl group at C-3 and the carboxylic group at C-17 played indispensable roles in the antiosteoclastogenesis activity of ursane-type triterpenoids. The configuration at C-3 (a beta-form of the hydroxyl group) was found to be important for this activity. While introducing a hydroxyl group at C-19 increased the inhibitory activity of ursane-type triterpenoids carrying an alpha-form hydroxyl group at C-3. The bioactivity analyses of ursolic acid and oleanolic acid demonstrated that the antiosteoclastogenesis effect of ursolic acid may be related to different positions of the C-29 and C-30 methyl groups on the E-ring, since oleanolic acid showed limited activity. The addition of a hydroxyl group at C-2 would dramatically improve the inhibition of oleanane-type triterpenoids. Collectively, these findings could provide important clues for the improvement of multi-targeted antiosteoclastogenesis agents from the leaves of E. japonica.

Antioxidative effect of loquat (Eriobotrya japonica Lindl.) fruit skin extract in soybean oil

The aim of this study was to compare the effects of solvent and ultrasound-assisted extraction methods with supercritical fluid extraction on antioxidant activity of loquat (Eriobotrya japonica Lindl.) fruit skin extract in stability of soybean oil at 25°C. Oxidative stability alterations of soybean oils containing 400 (SEA) and 1000 ppm (SEB) of ethanol extract, 400 (SSA) and 1000 ppm (SSB) of supercritical CO2 extract, 400 (SUA) and 1000 ppm (SUB) of ultrasound-assisted extract, and 100 ppm of tertiary butylhydroquinone (TBHQ) were monitored by measuring the peroxide value, thiobarbituric acid value, free fatty acids, conjugated dienes and trienes values. Oxidative changes in SEA were lower than that of oils treated with other extracts, but the best protection was observed in soybean oil consisting TBHQ. The solvent extraction method produces the maximum amount of phenolic and tocopherol compounds from loquat fruit skin. Therefore, solvent extraction method had a better effect on antioxidant activity of the loquat fruit skin extract.

Isolation and antimicrobial and antioxidant evaluation of bio-active compounds from eriobotrya japonica stems

PURPOSE

The present study was carried out to evaluate antimicrobial and antioxidant activities from Eriobotrya japonica stems as well investigation of its chemical composition.

METHODS

Methanol 80% extract of Eriobotrya japonica stems was tested for antimicrobial activity against bacterial and fungal strains and for antioxidant activity using oxygen radical absorbance capacity (ORAC) and the trolox equivalent antioxidant capacity (TEAC) assays and also total content of polyphenols with phytochemical analysis of the extract were determined.

RESULTS

The results showed that the extract has a significant antimicrobial activity, it inhibited significantly the growth of Candida albicans suggesting that it can be used in the treatment of fungal infections, and it showed no effect on the other bacterial and fungal strains, the extract has a good antioxidant activity, it has shown high values of oxygen radical absorbance capacity and trolox equivalent antioxidant capacity, while it showed a low value of polyphenol content. Phytochemical analysis of the extract showed the presence of carbohydrates, terpenes, tannins and flavonoids, further phytochemical analysis resulted in the isolation and identification of three triterpenic acids, oleanolic, ursolic and corosolic acids and four flavonoids, naringenin, quercetin, kaempferol 3-O-β-glucoside and quercetin 3-O-α-rhamnoside.

CONCLUSION

These results may help to discover new chemical classes of natural antimicrobial antioxidant substances.

Flavonoids, phenolics, and antioxidant capacity in the flower of Eriobotrya japonica Lindl

Flavonoids and phenolics are abundant in loquat flowers. Methanol had the highest extraction efficiency among five solvents, followed by ethanol. Considering the safety and residue, ethanol is better as extraction solvent. The average content of flavonoids and phenolics of loquat flower of five cultivars were 1.59 ± 0.24 and 7.86 ± 0.87 mg/g DW, respectively, when using ethanol as extraction solvent. The contents of both bioactive components in flowers at different developmental stages and in the various flower tissues clearly differed, with the highest flavonoids and phenolics content in flowers of stage 3 (flower fully open) and petal, respectively. The antioxidant capacity was measured using FRAP, DPPH, and ABTS methods. The values of ABTS method was highest, followed by DPPH, the lowest was FRAP, when using vitamin C equivalent antioxidant capacity (VCEAC) as unit. Correlation analysis showed that the ABTS method showed the highest correlation coefficients with flavonoids and phenolics, i.e., 0.886 and 0.973, respectively.

Determining total phenolic content and total antioxidant capacity of loquat cultivars grown in Hatay

Several fruit characteristics of five loquat (Eriobotrya japonica (Thunb.) Lindl.) cultivars/selections grown in Dörtyol, Hatay, Turkey were investigated in 2008. The cultivars/selections included 'Baduna 5', Güzelyurt 1, 'Hafif Cukurgöbek', 'Ottaviani,' and Type 1. The characteristics evaluated included fruit weight, width, length, seed number and weight, flesh/seed ratio, total soluble solids (TSS), pH, acidity, total phenolic (TP) content, and total antioxidant capacity (TAC), determined by the ferric reducing antioxidant power (FRAP) assay. The analyses were conducted by three replicates, with 30 fruits in each replicate. The results indicated that there were significant differences among the cultivars, for all the traits tested. For example, 'Hafif Cukurgöbek' and 'Ottaviani' had smaller fruits than others, although 'Hafif Cukurgöbek' had heavier seeds. The flesh/seed ratio was the highest in Type 1, while 'Hafif Cukurgöbek' had the highest pH and high soluble solids. 'Baduna 5' and 'Hafif Cukurgöbek' had the highest acidity. The TP ranged from 129 ('Baduna 5') to 578 ('Hafif Cukurgöbek') mg gallic acid equivalent (GAE)/kg fresh fruit (fw). 'Hafif Cukurgöbek' also had the highest FRAP mean (12.1 mmol Trolox Equivalent (TE)/kg fw). The results suggest that loquat cultivars have a variable range of TP content and a relatively high total antioxidant capacity, which is crucial for human health.