Transcriptome and biochemical analyses reveal phenolic compounds-mediated flavor differences in loquat (Eriobotrya japonica Lindl.) cultivars Chunhua No.1 and Dawuxing

The novel loquat cultivar 'Chunhua No.1' (CH1) is a promising commercial cultivar. However, CH1 has texture characteristics different from those of common loquat, and its formation mechanism remains unclear. Here, we first identified the phenolic compounds of CH1 and its parent ('Dawuxing', DWX) and the effect on texture formation. The special presence of stone cells explained the flavor differences in CH1. Chlorogenic acid, neochlorogenic acid, and coniferyl alcohol were the main phenolic compounds in loquat, and the high content of coniferyl alcohol was a potential factor for the rough texture of CH1. Transcriptome reveals that phenylpropanoid metabolism was activated during CH1 fruit texture formation. Kyoto Encyclopedia of Genes and Genomes (KEGG) identified 51 structural genes involved in phenylpropanoid biosynthesis, and Weighted Gene Co-expression Network Analysis (WGCNA) identified four structural genes and 88 transcription factors. These findings provide new insights into the phenolic metabolism and flavor formation of loquat fruit.

in China

Loquat, Rhaphiolepis loquata B.B.Liu & J.Wen (syn. Eriobotrya japonica) (Liu et al., 2020), is a subtropical evergreen fruit tree crop, for which China is the largest producer. Loquat fruit is favored by consumers for its attractive appearance, juicy taste, and rich nutrients (Tian et al., 2007). In May 2020, postharvest fruit rot was observed on loquat (about 10% of the fruits showed disease symptoms) in a local agricultural market (113°36'E, 23°11'N) of the Yuancun district in Guangzhou, China. The symptoms began with white mycelia above the epidermal surface of the fruits, then gradually developed into browning spots and soft lesions. To isolate and identify the pathogen, fruits (n=35) were surface disinfected by 1% NaOCl (1 min), 70% ethanol (30 s) and then washed twice with sterile distilled water and, thirty small pieces (3-5 mm2) were excised from the lesion margins. The excised tissue pieces were cultured on potato dextrose agar (PDA). After the colonies were established on PDA, the fungal strains were purified by the hyphal-tip method. Thirty-four fungal isolates were obtained from the infected isolation fruits (isolation frequency about 76%). Two morphologically similar isolates (PP-8 and PP-9) were used for further study. Fungal colonies were initially white, then turned brown with abundant aerial mycelia, and septate hyphae were 3.9 to 4.5 μm in diameter and branched at right angles with a constriction at the branch point. Binucleate cells were observed using safranin O-KOH solution stain and matched Ceratobasidium spp. (Binucleate Rhizoctonia spp.) morphological descriptions (Zhou et al. 2017). The molecular identity of the isolates was confirmed by sequencing the internal transcribed spacer (ITS) rDNA region and beta-tubulin (TUB) genes using the primer pairs ITS1/4 (White et al. 1990) and BT36F/BT12R, which were used for isolates belonging to the Rhizoctonia species complex (Thon and Royse 1999). BLASTN analysis of the two isolates sequences, which were deposited in GenBank (OP476745 and OP476746 for ITS; OR723969 and OR723968 for TUB), showed 95~97% identity with those of Ceratobasidium sp. (MT796446 and MF992150, DQ085499 and CP059650), respectively. The maximum-likelihood phylogenetic tree was analyzed based on the multiple-gene sequences of ITS and beta-tubulin sequences. The results showed that the isolates (PP-8 and PP-9) were confirmed as Ceratobasidium sp. Pathogenicity test was conducted on loquat. Six healthy fruits were inoculated with mycelial discs (5 mm in diameter) of the isolate after being wounded with a needle or unwounded. As negative control, six fruits were inoculated with PDA agar. All inoculated fruits were incubated in the dark at 26°C and 90% relative humidity for 7 days post inoculation. White mycelia were observed on the epidermal surface of both unwounded and wounded fruits, furthermore, the latter showed browning spots and rot lesions. Control fruits remained asymptomatic. Pathogenicity test was performed three times. The same fungal pathogen was re-isolated from inoculated fruits and identified by morphological observation and molecular analysis, thus confirming Koch's postulates. Ceratobasidium includes pathogens of members of the Annonaceae, Rosaceae, Rubiaceae, Rutaceae and Theaceae families, found in tropical agroecosystems in Africa, Asia and South America (Farr et al. 2022). To our knowledge, this is the first report of Ceratobasidium sp. causing postharvest fruit rot of loquat in China, further monitoring should be performed to quantify yield impacts and develop effective management strategies for this disease.

Valorization of loquat seeds by hydrothermal carbonization for the production of hydrochars and aqueous phases as added-value products

In the framework of circular bio-economy, waste loquat seeds were utilized for the production of two added-value products. The seeds were hydrothermally carbonized at a temperature range of 150-250 °C and time range 2-6 h and the resultant hydrochars and aqueous phases were characterized using various methods. The optimum higher heating value of 30.64 MJ kg-1, ash content of 1.99 wt % and alkali index of 0.05 were achieved for the hydrochar prepared at 250 °C and 6 h, establishing its suitability for energy-related applications. The aqueous phase obtained at 250 °C and 6 h achieved 90% scavenging of the 2,2-diphenyl-1-picryl-hydrazyl-hydrate (DPPH) radical and had a IC50 value of 43.71 μg mL-1. Principal component analysis showed that the production of phenols, ketones, alkenes and organic acids was favored at >200 °C, whereas furans and aldehydes were primarily formed at 150 °C. Conclusively, both added-value products were obtained at the same optimum hydrothermal carbonization conditions of 250 °C and 6 h treatment time. In a bio-refinery context, this has the practical implication that both bio-products be obtained simultaneously, without the need to switch between different temperatures and residence times.

Warm temperature during floral bud transition turns off EjTFL1 gene expression and promotes flowering in Loquat (Eriobotrya japonica Lindl.)

The Rosaceae family includes several deciduous woody species whose flower development extends over two consecutive growing seasons with a winter dormant period in between. Loquat (Eriobotrya japonica Lindl.) belongs to this family, but it is an evergreen species whose flower bud initiation and flowering occur within the same growing year. Vegetative growth dominates from spring to late summer when terminal buds bloom as panicles. Thus, its floral buds do not undergo winter dormancy until flowering, but a summer heat period of dormancy is required for floral bud differentiation, and that is why we used loquat to study the mechanism by which this summer rest period contributes to floral differentiation of Rosaceae species. As for the deciduous species, the bud transition to the generative stage is initiated by the floral integrator genes. There is evidence that combinations of environmental signals and internal cues (plant hormones) control the expression of TFL1, but the mechanism by which this gene regulates its expression in loquat needs to be clarified for a better understanding of its floral initiation and seasonal growth cycles. Under high temperatures (>25ºC) after floral bud inductive period, EjTFL1 expression decreases during meristem transition to the reproductive stage, and the promoters of flowering (EjAP1 and EjLFY) increase, indicating that the floral bud differentiation is affected by high temperatures. Monitoring the apical meristem of loquat in June-August of two consecutive years under ambient and thermal controlled conditions showed that under lower temperatures (<25ºC) during the same period, shoot apex did not stop growing and a higher EjTFL1 expression was recorded, preventing the bud to flower. Likewise, temperature directly affects ABA content in the meristem paralleling EjTFL1 expression, suggesting signaling cascades could converge to refine the expression of EjTFL1 under specific conditions (Tª<25ºC) during the floral transition stage.

Loquat seed starch - Emerging source of non-conventional starch: Structure, properties, and novel applications

Recently, non-conventional sources of starch have attracted attention due to their potential to provide cost-effective alternatives to traditional starch. Among non-conventional starches, loquat (Eriobotrya japonica) seed starch is an emerging source of starch consisting of the amount of starch (nearly 20 %). Due to its unique structure, functional properties, and novel applications, it could be utilized as a potential ingredient. Interestingly, this starch has similar properties as commercial starches including high amylose content, small granule size, and high viscosity and heat stability, making it an attractive option for various food applications. Therefore, this review mainly covers the fundamental understanding of the valorization of loquat seeds by extracting the starch using different isolation methods, with preferable structural, morphological, and functional properties. Different isolation and modification methods (wet milling, acid, neutral and alkaline) are effectively used to obtain higher amounts of starch are revealed. Moreover, insight into various analytical techniques including scanning electron microscopy, differential scanning calorimetry, and X-ray diffraction used to characterize the molecular structure of the starch are discussed. In addition, the effect of shear rate and temperature on rheological attributes with solubility index, swelling power, and color is revealed. Besides, this starch contains bioactive compounds that have shown a positive impact on the enhancement of the shelf-life of the fruits. Overall, loquat seed starches have the potential to provide sustainable and cost-effective alternatives to traditional starch sources and can lead to novel applications in the food industry. Further research is needed to optimize processing techniques and develop value-added products that can be produced at a large scale. However, there is relatively limited published scientific evidence on the structural and morphological characteristics of loquat seed starch. Thus, in this review, we focused on different isolation techniques of loquat seed starch, its structural and functional characteristics, along with potential applications.

Identification and characterization of cytochrome P450 CYP77A59 of loquat (Rhaphiolepis bibas) responsible for biosynthesis of phenylacetonitrile, a floral nitrile compound

MAIN CONCLUSION

Cytochrome P450 CYP77A59 is responsible for the biosynthesis of phenylacetonitrile in loquat flowers. Flowers of some plants emit volatile nitrile compounds, but the biosynthesis of these compounds is unclear. Loquat (Rhaphiolepis bibas) flowers emit characteristic N-containing volatiles, such as phenylacetonitrile (PAN), (E/Z)-phenylacetaldoxime (PAOx), and (2-nitroethyl)benzene (NEB). These volatiles likely play a defense role against pathogens and insects. PAN and NEB are commonly biosynthesized from L-phenylalanine via (E/Z)-PAOx. Two cytochrome P450s-CYP79D80 and "promiscuous fatty acid ω-hydroxylase" CYP94A90, which catalyze the formation of (E/Z)-PAOx from L-phenylalanine and NEB from (E/Z)-PAOx, respectively-are involved in NEB biosynthesis. However, the enzymes catalyzing the formation of PAN from (E/Z)-PAOx in loquat have not been identified. In this study, we aimed to identify candidate cytochrome P450s catalyzing PAN formation in loquat flowers. Yeast whole-cell biocatalyst assays showed that among nine candidate cytochrome P450s, CYP77A58 and CYP77A59 produced PAN from (E/Z)-PAOx. CYP77As catalyzed the dehydration of aldoximes, which is atypical of cytochrome P450; the reaction was NADPH-dependent, with an optimum temperature and pH of 40 °C and 8.0, respectively. CYP77As acted on (E/Z)-PAOx, (E/Z)-4-hydroxyphenylacetaldoxime, and (E/Z)-indole-3-acetaldoxime. Previously characterized CYP77As are known to hydroxylate fatty acids; loquat CYP77As did not act on tested fatty acids. We observed higher expression of CYP77A59 in flowers than in buds; expression of CYP77A58 was remarkably reduced in the flowers. Because the flowers, but not buds, emit PAN, CYP77A59 is likely responsible for the biosynthesis of PAN in loquat flowers. This study will help us understand the biosynthesis of floral nitrile compounds.

Detection of early bruises on loquat using hyperspectral imaging technology coupled with band ratio and improved Otsu method

The bruising is one of the major factors affecting the quality of loquat and the bruised areas of loquat are also prone to harbor bacteria and molds. Therefore, it is critical to detect early bruises of loquat. In this study, a method based on hyperspectral imaging technology coupled with band ratio and improved Otsu method was proposed to detect early bruises of loquat. Firstly, the principal component cluster analysis was used to analyze the three regions of Vis-NIR (397.5-1014.0 nm), Vis (397.5-780.0 nm), and NIR (780.0-1014.0 nm), respectively. It was found that the Vis-NIR and NIR spectral regions along PC1 could be used to effectively distinguish bruised tissues. Then, the key wavelength images corresponding to the two regions were selected according to the load curve, respectively, and two sets of PC images and band ratio images of them were established. After comparison, it was found that the band ratio image Q_{651.3 / 904.3} was the most suitable for subsequent analysis of detecting early bruises of loquat. Finally, in order to evaluate the segmentation effect of the improved Otsu method, the segmentation results of the global threshold and the Otsu method were compared with it, respectively, and it was found that the performance of the improved Otsu method was best. However, since the stem-end area and the bruised area have similar intensity features causing mis-segmentation, the stem-end area was removed by curvature-assisted Hough transform circle detection (CACD) algorithm. And all test set samples were used to evaluate the performance of the proposed method, and the overall accuracy of it was 96.0 %. The results show that the detection method proposed in this study has the potential to detect early bruises of loquat in online practical applications, and it provides a theoretical basis for hyperspectral imaging in the bruise detection of fruit.

Evolutionary origin and functional specialization of Dormancy-Associated MADS box (DAM) proteins in perennial crops

BACKGROUND

Bud dormancy is a phenological adaptation of temperate perennials that ensures survival under winter temperature conditions by ceasing growth and increasing cold hardiness. SHORT VEGETATIVE PHASE (SVP)-like factors, and particularly a subset of them named DORMANCY-ASSOCIATED MADS-BOX (DAM), are master regulators of bud dormancy in perennials, prominently Rosaceae crops widely adapted to varying environmental conditions.

RESULTS

SVP-like proteins from recently sequenced Rosaceae genomes were identified and characterized using sequence, phylogenetic and synteny analysis tools. SVP-like proteins clustered in three clades (SVP1-3), with known DAM proteins located within SVP2 clade, which also included Arabidopsis AGAMOUS-LIKE 24 (AthAGL24). A more detailed study on these protein sequences led to the identification of a 15-amino acid long motif specific to DAM proteins, which affected protein heteromerization properties by yeast two-hybrid system in peach PpeDAM6, and the unexpected finding of predicted DAM-like genes in loquat, an evergreen species lacking winter dormancy. DAM gene expression in loquat trees was studied by quantitative PCR, associating with inflorescence development and growth in varieties with contrasting flowering behaviour.

CONCLUSIONS

Phylogenetic, synteny analyses and heterologous overexpression in the model plant Arabidopsis thaliana supported three major conclusions: 1) DAM proteins might have emerged from the SVP2 clade in the Amygdaloideae subfamily of Rosaceae; 2) a short DAM-specific motif affects protein heteromerization, with a likely effect on DAM transcriptional targets and other functional features, providing a sequence signature for the DAM group of dormancy factors; 3) in agreement with other recent studies, DAM associates with inflorescence development and growth, independently of the dormancy habit.

First report of apple stem grooving virus infection in loquat from India

Loquat, commonly known as Eriobotrya japonica, is a major subtropical fruit from the Rosaceae family that is native to China but also found in most of Europe and Asia, including India. Apple stem grooving virus (ASGV) infecting loquat was detected using leaf samples collected from Himachal Pradesh (India) through DAC-ELISA followed by RT-PCR assays targeting coat protein (CP), movement protein (MP) and replicase (Rep) regions of ASGV genome. Sequencing of RT-PCR amplicons and sequence analyses revealed that CP, MP and Rep sequences of ASGV loquat Indian isolate of the current study shared a maximum of 98-100% nucleotide sequence identities with the corresponding sequences of available ASGV Indian isolates [LN559078, HE978837, MZ127820, MN912568]. Phylogenetic tree based on each sequenced gene confirmed the genetic diversity of ASGV. To the best of our knowledge, and based on review of the literature, this is the first report of ASGV infection in loquat from India.

Protective mechanisms of loquat leaf extract and ursolic acid against diabetic pro-inflammation

The pharmacological effectiveness of loquat leaf extract (LE) and its important component, ursolic acid (UA), in the treatment of diabetes mellitus, has been well established in traditional medicine; however, the mechanism underlying their action is still unclear. We evaluated the protective effects of LE and UA against hyperglycemia-induced advanced glycation end product (AGE) formations and hepatic pro-inflammation. Oral administration of UA and LE at a dose of 50 mg/kg/day for 15 days yielded no significant hypoglycemic effect in diabetic db/db mice. UA and LE suppressed hepatic oxidative stress and AGE formation in diabetic mice, and this was followed by the downregulated mitogen-activated protein kinase signaling and nuclear factor κ B (NF-κB) activity. To identify the molecular target of LE and UA, a docking simulation was performed, and this predicted UA to bind to liver kinase B1 (LKB1), an upstream of AMP-activated protein kinase (AMPK)/transcription factor forkhead box O3 (FOXO3) axis. UA reversed the high-glucose-induced downregulation of LKB1-AMPK1-FOXO3 activation and antioxidant gene transcription. These findings demonstrated the antioxidant and anti-inflammatory effects of UA and LE against hyperglycemia-induced hepatic inflammation. Furthermore, we speculate that the LKB1/AMPK/FOXO3 pathway is a potential target responsible for these beneficial effects of LE and UA.

Extraction and identification of proanthocyanidins from the leaves of persimmon and loquat

Proanthocyanidins is flavan-3-ol polymers with many activities which attracted a lot of attention. However, most of the proanthocyanidins come from fruits and seeds, resulting in higher costs. The extraction of proanthocyanidins from leaves that were trimmed as wastes from fruit trees is of good economic benefits. The proanthocyanidins in persimmon leaves and loquat leaves were extracted and purified. The purity of persimmon and loquat leaves were 85.33 ± 0.11% and 88.45 ± 0.96% with yield of 3.40% and 2.37% respectively. Detailed structure information was analyzed. Persimmon leaves proanthocyanidins mainly consist of catechin with B-type link along with a small portion of gallocatechin, catechin gallate and A-type link. Loquat leaves proanthocyanidins consist of catechin, gallocatechin, gallocatechin gallate and afzelechin with B-type link along with a small portion of A-type link. The α-amylase inhibition effect of the two leaves was analyzed. Persimmon leaves proanthocyanidins and loquat leaves proanthocyanidins were two mixed-type inhibitors to α-amylase.

Genotyping of polyploid plants using quantitative PCR: application in the breeding of white-fleshed triploid loquats (Eriobotrya japonica)

BACKGROUND

Ploidy manipulation is effective in seedless loquat breeding, in which flesh color is a key agronomic and economic trait. Few techniques are currently available for detecting the genotypes of polyploids in plants, but this ability is essential for most genetic research and molecular breeding.

RESULTS

We developed a system for genotyping by quantitative PCR (qPCR) that allowed flesh color genotyping in multiple tetraploid and triploid loquat varieties (lines). The analysis of 13 different ratios of DNA mixtures between two homozygous diploids (AA and aa) showed that the proportion of allele A has a high correlation (R² = 0.9992) with parameter b [b = a₁/(a₁ + a₂)], which is derived from the two normalized allele signals (a₁ and a₂) provided by qPCR. Cluster analysis and variance analysis from simulating triploid and tetraploid hybrids provided completely correct allelic configurations. Four genotypes (AAA, AAa, Aaa, aaa) were found in triploid loquats, and four (AAAA, AAAa, AAaa, Aaaa; absence of aaaa homozygotes) were found in tetraploid loquats. DNA markers analysis showed that the segregation of flesh color in all F₁ hybrids conformed to Mendel's law. When tetraploid B431 was the female parent, more white-fleshed triploids occurred among the progeny.

CONCLUSIONS

qPCR can detect the flesh color genotypes of loquat polyploids and provides an alternative method for analyzing polyploid genotype and breeding, dose effects and allele-specific expression.

Physiological and transcriptomics analysis of the effect of recombinant serine protease on the preservation of loquat

This study aimed to explore the effects of recombinant serine protease treatment on the development of post-harvest loquat diseases, fruit quality, and disease resistance enzyme activities. It also sought to analyze differential genes expression using RNA-seq technology. Transcriptomics analysis revealed 708 and 398 differentially expressed genes (DEGs) in loquat fruits treated with serine protease for 24 and 48 h. Furthermore, 2198 DEGs were obtained between 24 and 48 h after treatment. The genes encoding JAZ, MYC2 and ERF in the plant signal transduction pathway were significantly up-regulated. The resistance-related genes, such as PPO, PAL, TLP, WRKY, and transcription factors were also significantly up-regulated. These results indicated that the recombinant serine protease can induce plant signal transduction pathway in loquat fruit. The expression of some resistance-related genes enhanced the disease resistance of loquat fruit and revealed the molecular mechanism of loquat fruit resistance induced by recombinant serine protease.

UHPLC-QTOF-MS based metabolomics and biological activities of different parts of Eriobotrya japonica

Eriobotrya japonica, commonly known as loquat, has been used traditionally for the treatment of different diseases. Herein, untargeted profiling based on ultra-high-performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry (UHPLC-QTOF-MS) was used to depict the phytochemical profile of loquat roots, leaves, stems, seeds, and fruits. This allowed the tentative annotation of 349 compounds, representing different phytochemical classes that included flavonoids, phenolic acids, lignans, stilbenes, and terpenoids. Among others, low molecular weight phenolics (tyrosol derivatives) and terpenoids were the most abundant phytochemicals. After that, in vitro antioxidant and enzyme inhibition assays were applied to investigate the biological activity of the different organs of Eriobotrya japonica. Roots of E. japonica exhibited the highest antioxidant capacity, showing 181.88, 275.48, 325.18, 169.74 mg Trolox equivalent (TE)/g in DPPH, ABTS, CUPRAC, and FRAP assays, respectively. Furthermore, the root extract of E. japonica strongly inhibited butyryl cholinesterase (3.64 mg galantamine equivalent (GALAE)/g), whereas leaves, stems, seeds, and fruits showed comparable inhibition of both acetyl and butyryl cholinesterases. All the investigated organs of E. japonica exhibited in vitro tyrosinase inhibition (57.27-71.61 mg Kojic Acid Equivalent (KAE)/g). Our findings suggest a potential food and pharmaceutical exploitation of different organs of E. japonica (mainly roots) in terms of enrichment with health-promoting phenolics and triterpenes.

First report of Fusarium solani Species Complex Causing Root Rot of Loquat (Eriobotrya japonica) in China

Loquat (Eriobotrya japonica), a native fruit tree to China, is a popular edible fruit with medicinal properties (Badenes et al. 2013). A 2016-2019 field survey of ~13,000 loquat trees in two orchards in Chongqing and Fujian provinces showed about 5 to 10% root rot disease incidence. The disease symptoms included leaf yellowing, wilting, rotting of main root, and cracking of lateral roots, eventually leading to defoliation and death. To determine the causative agent, diseased roots from six trees were collected, washed in tap water, cut into 2-3 mm pieces, and disinfected for 3 min in 75% (v/v) EtOH. After rinsing in sterilized water, the root pieces were soaked in 10% NaClO (w/v) for 5-10 min, rinsed thrice in sterile water, and plated on potato dextrose agar (PDA). After 7 days of incubation at 25°C, individual spores were collected from the fungal colonies and replated. Single spore cultures growing on PDA gave rise to woolly-cottony, cream-white colored aerial mycelium and a yellowish pigmented mycelium. The average colony growth rate was 8.6 mm day-1 (n=3). Microscopic observation of the mycelium revealed septate and hyaline hyphae and long cylindrical monophialides. Macroconidia were moderately curved, stout, 3-4 septate, measuring 20.79-48.70 μm × 4.16-10.14 μm (n=50). Microconidia produced from long phialides were kidney-shaped, 0-2 septate, and 5.72-17.28 μm × 2.29-6.51 μm (n=50) in size. The mycelial characteristics and reproductive structures of the isolates fit the morphological description of Fusarium sp. (Summerell et al. 2003). To confirm this identification, translation elongation factor (EF-1α) and RNA polymerase I beta subunit (RPB1) and RNA polymerase II beta subunit (RPB2) regions of the genome were PCR amplified from 3 separate isolates (R2, R4 and R5) using EF1/ EF2, RPB1-Fa/G2R, RPB2-5f2/7cR & RPB2-7cF/11aR primer pairs (O'Donnell et al. 2010) and sequenced. BLASTn comparison of the EF-1α (MT976167), RPB1 (MT967271) and RPB2 (MW233052) regions from isolate R4 showed 99% identity with the EF-1α (GU170620, 675/676 bp), RPB1 (KC808270, 1543/1545 bp) and RPB2 (MK4419902, 1637/1638 bp) sequences of Fusarium solani species complex (FSSC) in GenBank database. The same species level identification was also found using FUSARIUM-ID and FUSARIUM-MLDT databases. Two-year-old seedlings (n=3) of two different cultivars, 'Hunanzaoshu' and 'Huabai No. 1', growing in pots indoors at 25-27 °C were inoculated by drenching the soil with a conidial suspension of isolate R4 (40 mL, 106 conidia mL-1 obtained from 6-10 day old cultures). Control plants (n=3) were inoculated with sterilized water. At 20 days after inoculation (DAI) the leaves of inoculated plants became chlorotic and wilted, defoliated over time, and by 53 DAI 91.67% of plants died. The taproot and lateral roots of inoculated plants appeared brown to black in color and most lateral roots died and decomposed at 53 DAI, whereas the control plant roots remained healthy. All control plants remained symptomless. Based on morphological and molecular characters (TEF-1, RPB1 and RPB2), the re-isolated pathogen from diseased plants was identical to the R4 isolate used for inoculation and the disease assays were repeated thrice. FSSC was recently reported to cause fruit rot disease on loquat in Pakistan (Abbas et al. 2017). Identifying Fusarium solani species complex as a disease agent in Chinese loquat will assist in future development of improved germplasm for this important worldwide tree crop.

Quantification of amygdalin, prunasin, total cyanide and free cyanide in powdered loquat seeds

Amygdalin, prunasin, total cyanide and free cyanide concentrations in 12 powdered loquat seeds were investigated. Loquat (Eriobotrya japonica) is a species of flowering plant in the family Rosaceae, and its fruit is quite popular in Japan. Amygdalin and prunasin were measured using LC-MS/MS. Total cyanide was measured by enzymatic treatment, steam distillation and colorimetric quantification using the pyridine-pyrazolone method. Free cyanide was measured without enzymatic treatment. The mean concentrations of amygdalin, prunasin, total cyanide and free cyanide in powdered loquat seeds were 5900, 760, 410 and 44 mg/kg, respectively. The range of each quantitative value was extensive. Seven out of twelve samples were at risk for exceeding the acute reference dose (ARfD) of cyanide.

Effect of nano-SiO2 packing on postharvest quality and antioxidant capacity of loquat fruit under ambient temperature storage

Effect of nano-SiO₂ packing on postharvest quality and antioxidant capacity of two different loquat cultivars (white-flesh 'Qingzhong' and red-flesh 'Dawuxing') were determined. Results showed that nano-SiO₂ packing significantly inhibited internal browning, retarded the decline of total soluble solids, titratable acidity, ascorbic acid content and extractable juice in both cultivars. Decay index of nano-SiO₂ packing in 'Dawuxing' and 'Qingzhong' was 53.25% and 42.84% lower than control after the day 12, respectively. Meanwhile, nano-SiO₂ packing enhanced the contents of individual phenolic compounds and soluble sugar compounds, induced higher superoxide dismutase and catalase activities, which contributed to improving 1,1-diphenyl-2-picrylhydrazyl and hydroxyl radical scavenging capacity. Furthermore, the contents of total soluble solids, ascorbic acid and soluble sugar were higher in 'Qingzhong' than those in 'Dawuxing', which dedicated to better quality. These results indicated that nano-SiO₂ packing was a promising approach in inhibiting decay, maintaining quality and expanding shelf life of loquats.

Anti-inflammatory and anti-arthritic activity in extract from the leaves of Eriobotrya japonica

ETHNOPHARMACOLOGICAL RELEVANCE

The Eriobotrya japonica (EJ) is a Chinese medicinal plant that is currently grown in Brazil. E. japonica leaves infusion is traditionally used in the treatment of inflammation; however, there are few scientific studies showing the effects of these properties on joint articular and persistent experimental inflammation.

AIM OF THE STUDY

The present research had objective investigation of the effect of infusion obtained from leaves of E. japonica (EJLE) on acute and persistent experimental articular inflammation.

MATERIALS AND METHODS

The Swiss mice were treated orally with EJLE and analyzed for acute pleural inflammation (30, 100, and 300 mg/kg), paw edema induced by carrageenan (100 mg/kg), acute knee inflammation induced by zymosan (100 mg/kg), and persistent inflammation induced by Complete Freund's Adjuvant (CFA) (30 and 100 mg/kg). Mechanical hyperalgesia, cold and edema were analyzed.

RESULTS

The chromatographic analysis of EJLE revealed the presence of corosolic acid, oleanolic acid, and ursolic acid. EJLE presented anti-inflammatory activity in the pleurisy model, inhibiting leukocyte migration, protein extravasation and nitric oxide production. In the articular inflammation model, EJLE reduced the number of leukocytes in the joint cavity, paw edema and hyperalgesia (4 h after induction). In the persistent inflammation model induced by CFA, the extract reduced paw edema after 11 days of mechanical and cold hyperalgesia on day 6.

CONCLUSIONS

The EJLE has anti-inflammatory and antihyperalgesic potential in models of acute and persistent experimental articular inflammation, making this infusion a new possibility for complementary treating acute or chronic articular inflammatory diseases.

Molecular karyotypes of loquat (Eriobotrya japonica) aneuploids can be detected by using SSR markers combined with quantitative PCR irrespective of heterozygosity

BACKGROUND

Aneuploidy, a condition caused by an imbalance between the relative dosages of chromosomes, generally produces a novel phenotype specific to the molecular karyotype. Few techniques are currently available for detecting the molecular karyotypes of aneuploids in plants.

RESULTS

Based on this imbalance in chromosome dosage, a new approach (referred to as 'SSR-qPCR') combining simple sequence repeat (SSR) markers and quantitative real-time PCR (qPCR) has been developed and utilized to detect some common aneuploids irrespective of heterozygosity. We screened 17 specific SSR markers covering all loquat linkage groups and redesigned 6 pairs of primers for SSR markers that can detect loquat chromosome aneuploidies. The SSR-qPCR detection results obtained for hybrid progeny and open-pollination progeny of triploid loquat showed diagnostic accuracies of 88.9% and 62.5%, respectively, compared with the chromosome preparation results.

CONCLUSION

SSR-qPCR can detect loquat aneuploids and be used to construct the entire molecular karyotypes of aneuploid individuals. Therefore, this method offers a novel alternative for the detection of chromosome aneuploidies.

Polysaccharides from loquat (Eriobotrya japonica) leaves: Impacts of extraction methods on their physicochemical characteristics and biological activities

Impacts of hot water extraction (HWE), pressurized water extraction (PWE), high-speed shearing homogenization extraction, microwave assisted extraction (MAE), ultrasound assisted extraction (UAE), ultrasound assisted enzymatic extraction, and ultrasound-microwave assisted extraction (UMAE) on physicochemical characteristics and bioactivities of polysaccharides from loquat (Eriobotrya japonica) leaves (LLPs) were investigated. Results showed that the degrees of esterification, contents of phenolics and uronic acids, constituent monosaccharides, apparent viscosities, and molecular weights of LLPs varied by different extraction methods. Bioactivities of LLPs were also significantly affected by different extraction methods. The high molecular weight and high degree of esterification of LLP-W and LLP-P extracted by HWE and PWE, respectively, might contribute to their strong binding capacities. The strong antioxidant activities and inhibitory effects on α-amylase and α-glucosidase were found in LLP-M and LLP-U extracted by MAE and UAE, respectively, which might be attributed to their contents of uronic acids, contents of total phenolics, and molecular weights. The low molecular weights and viscosities of LLP-U and LLP-UM extracted by UMAE might contribute to their strong prebiotic effects. These findings could provide scientific foundations for selecting appropriate extraction methods to obtain LLPs with desired bioactivities for applications in the pharmaceutical and functional food industries.

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.

Functional characterization of GI and CO homologs from Eriobotrya deflexa Nakai forma koshunensis

The first report of the cloning and characterization of the flowering time-regulating genes GI and CO homologs from loquat. Flowering time is critical for successful reproduction in plants. In fruit trees, it can also influence the fruit yield and quality. In the previous work, we cloned the important florigen one EdFT and two EdFDs from wild loquat (Eriobotrya deflexa Nakai forma koshunensis); however, the upstream transcription factors are still unknown. The photoperiod pathway genes GIGANTEA (GI) and CONSTANS (CO) have been reported to mainly regulate FT expression in model plants. In this work, we first cloned photoperiod pathway orthologs EdGI and EdCO from E. deflexa Nakai f. koshunensis. Phylogenetic analysis showed they are highly conserved to those from Arabidopsis. They are mainly expressed in the leaves. The EdGI and EdCO were localized in the nucleus. Their expression showed in photoperiodic regulation, while the EdCO transcripts reached the peak at different periods from that of CO in Arabidopsis. Moreover, EdCO significantly activated the EdFT promoter activity. In the transgenic Arabidopsis, downstream-flowering genes like FT and AP1 were obviously upregulated, and consequently resulted in early-flowering phenotype compared to the wild type. These data revealed that the EdGI and EdCO may play a similar role as GI and CO in Arabidopsis, and regulate flower initiation in loquat.

Selection of the optimal reference genes for expression analyses in different materials of Eriobotrya japonica

BACKGROUND

Loquat (Eriobotrya japonica) is a subtropical tree bearing fruit that ripens during late spring and early summer, which is the off-season for fruit production. The specific flowering habit of loquat, which starts in fall and ends in winter, has attracted an increasing number of researchers who believe that it may represent an ideal model for studying flowering shift adaptations to climate change in Rosaceae. These studies require an understanding of gene expression patterns within the fruit and other tissues of this plant. Although ACTINs (ACTs) have previously been used as reference genes (RGs) for gene expression studies in loquats, a comprehensive analysis of whether these RGs are optimal for normalizing RT-qPCR data has not been performed.

RESULTS

In this study, 11 candidate RGs (RIBOSOMAL-LIKE PROTEIN4 (RPL4), RIBOSOMAL-LIKE PROTEIN18 (RPL18), Histone H3.3 (HIS3), Alpha-tubulin-3 (TUA3), S-Adenosyl Methionine Decarboxylase (SAMDC), TIP41-like Family Protein (TIP41), (UDP)-glucose Pyrophosphorylase (UGPase), 18S ribosomal RNA (18S), Glyceraldehyde-3-phosphate Dehydrogenase (GAPDH), Plasma Intrinsic Protein 2 (PIP2) and ACTIN(ACT)) were assessed to determine their expression stability in 23 samples from different tissues or organs of loquat. Integrated expression stability evaluations using five computational statistical methods (GeNorm, NormFinder, ΔCt, BestKeeper, and RefFinder) suggested that a RG set, including RPL4, RPL18, HIS3 and TUA3, was the most stable one across all of the tested loquat samples. The expression pattern of EjCDKB1;2 in the tested loquat tissues normalized to the selected RG set demonstrated its reliability.

CONCLUSIONS

This study reveals the reliable RGs for accurate normalization of gene expression in loquat. In addition, our findings demonstrate an efficient system for identifying the most effective RGs for different organs, which may be applied to related rosaceous crops.

Integrating proteomic and transcriptomic analyses of loquat (Eriobotrya japonica Lindl.) in response to cold stress

The expression levels of many genes and the related proteins change and regulate physiological and metabolic processes that help the plant survive harsh environmental conditions under cold stress. Damage due to cold and freezing conditions often causes dynamic loss of loquat fruits in cultivated parts of northern China. To illustrate the mechanism of cold tolerance in the loquat, we combined the transcriptomic analysis with isobaric tags for relative and absolute quantification (iTRAQ) and RNA sequencing (RNA-Seq) data from loquat leaves under 4 °C treatment. The results showed 122,081 genes and 1210 differentially expressed genes (DEGs), while only 4582 proteins and 300 differential proteins (DEPs) were identified. Functional annotation and Kyoto Encyclopaedia of Genes and Genomes (KEGG) pathway analysis indicated that metabolic pathways and biosynthesis of secondary metabolites were the two most common pathways in transcriptional and translational processes in this study. Comparison analysis of the transcriptomic and proteomic profiles, only 27 of 3620 genes were found to be shared both in DEGs and DEPs. Further validation with Real-Time Quantitative RT-PCR analysis showed that the genes expression of NADP-dependent D-sorbitol-6-phosphate dehydrogenase, anthocyanin synthase and phenylalanine ammonia-lyase were consistent with the pattern of transcriptome profile, which suggested that these three genes might play vital roles in cold tolerance in loquat.

Comparison of structural and functional properties of starches from five fruit kernels

Starch was isolated from the kernels of jackfruit, longan, loquat, litchi, and mango fruits, which contained approximately 56, 59, 71, 53, and 64% starch, respectively, indicating that these fruit kernels are good starch sources. The structural and functional properties of these isolated starches were investigated and compared. The starches had irregular, truncated, spherical, and elliptical shapes with central hila and exhibited different sizes, with mango starch being the largest and jackfruit and longan starches being the smallest. The five starches had similar amylose contents but exhibited significantly different crystalline properties including crystalline type, relative crystallinity, short-range ordered structure, and lamellar intensity. Among the five starches, the jackfruit and loquat starches had the highest and lowest gelatinization temperature and enthalpy, respectively, and the litchi and mango starches had the highest and lowest pasting viscosity, respectively. The longan and loquat starches were more susceptible to enzyme hydrolysis than the other starches.

Targeted Quantification of Isoforms of a Thylakoid-Bound Protein: MRM Method Development

Targeted mass spectrometric methods such as selected/multiple reaction monitoring (SRM/MRM) have found intense application in protein detection and quantification which competes with classical immunoaffinity techniques. It provides a universal procedure to develop a fast, highly specific, sensitive, accurate, and cheap methodology for targeted detection and quantification of proteins based on the direct analysis of their surrogate peptides typically generated by tryptic digestion. This methodology can be advantageously applied in the field of plant proteomics and particularly for non-model species since immunoreagents are scarcely available. Here, we describe the issues to take into consideration in order to develop a MRM method to detect and quantify isoforms of the thylakoid-bound protein polyphenol oxidase from the non-model and database underrepresented species Eriobotrya japonica Lindl.

Volatile metabolite profiling reveals the changes in the volatile compounds of new spontaneously generated loquat cultivars

In recent years, the advantageous traits of three new loquat cultivars have drawn the attention of breeders and growers. All three have spontaneously arisen from the 'Algerie' cultivar: the new 'Xirlero' cultivar is a bud mutant of 'Algerie', while 'Amadeo' and 'Raúl' arose as chance seedlings. Following a non-targeted approach based on HS-SPME-GC-MS, the volatile compounds profile of the fruits from the new cultivars were obtained and compared to the original 'Algerie' cultivar. Carboxylic acids clearly dominated the volatile profile of all the loquat cultivars, but esters, aldehydes, ketones and alcohols were also predominant compounds. Interestingly when the bud mutant event did not lead to marked changes in the volatile compounds complement, pronounced changes in the volatile composition of chance seedling-generated cultivars 'Amadeo' and 'Raúl' were observed. 'Amadeo' fruits showed lower levels of 2-methyl butanoic acid and much higher levels of methylhexanoate, methylbutanoate and 2-hydroxy-5-methylacetophenone. The 'Raúl' cultivar also had a distinctive volatile profile characterised by high levels of C6-aldehydes, (E)-2-hexanal, 2-hexenal, (Z)-3-hexenal and hexanal, and several carotenoid-derived volatiles; e.g. 2-pentene-1,4-dione 1-(1,2,2-trimethylcyclopentyl), (S)-dihydroactinidiolide, isodurene, cis-geranyl acetone, β-damascenone, β-ionone, α-ionone and 3,4-dehydro-β-ionone. These changes in volatiles were associated with a more intense flavour in cultivars 'Amadeo' and 'Raúl', according to the sensory evaluation of the flavour intensity carried out by a semi-trained panel. A metabolomic correlation network analysis provided insights as to how volatiles were regulated, and revealed that the compounds modified in 'Amadeo' were uncoupled from the rest of the volatilome, while the volatiles modified in 'Raul' changed according to specific groups. To conclude, this work provides a holistic view of how the loquat volatilome was affected, and this information was integrated with the physical-chemical-sensory attributes to understand the changes that occur in the new cultivars.

Comparative transcriptome profiling of freezing stress responses in loquat (Eriobotrya japonica) fruitlets

Loquat (Eriobotrya japonica Lindl.) is an important subtropical, commercial fruit in China. It blossoms during autumn and winter in most areas of China and its fruitlets usually suffer from freezing stress. However, studies about the mechanisms underlying freezing stress in loquat are very limited. The gene expression profiles of loquat fruitlets subjected to freezing (G2 library) versus non-treated ones (G1 library) were investigated using Illumina sequencing technology to elucidate the molecular mechanisms and identify the genes that play vital roles in the freezing stress response. The results showed that approximately 157.63 million reads in total were obtained from freeze-treated and non-treated loquat fruitlets. These reads were assembled into 87,379 unigenes with an average length of 710 bp and an N50 of 1,200 bp. After comparing the profiles obtained from the G1 and G2 libraries, 2,892 differentially expressed genes were identified, of which 1,883 were up-regulated and 1,009 were down-regulated in the treated samples compared to non-treated ones. These unigenes showed significant differences in expression for carbohydrate transport and metabolism, amino acid metabolism, energy metabolism, and lipid metabolism, which are involved in defense against freezing stress. Glycolysis/gluconeogenesis was one of the most significantly regulated pathways. Freezing also significantly damaged the membrane system of loquat fruitlets, and several defense mechanisms were induced. Some selected genes related to low temperature resistance were validated by quantitative real-time PCR (qRT-PCR). The results revealed many genes and pathways that are part of freezing resistance processes and expand our understanding of the complex molecular events involved in freezing stress.

Ethylene biosynthesis and perception during ripening of loquat fruit (Eriobotrya japonica Lindl.)

In order to gain insights into the controversial ripening behavior of loquat fruits, in the present study we have analyzed the expression of three genes related to ethylene biosynthesis (ACS1, ACO1 and ACO2), two ethylene receptors (ERS1a and ERS1b), one signal transduction component (CTR1) and one transcription factor (EIL1) in peel and pulp of loquat fruit during natural ripening and also in fruits treated with ethylene (10μLL^-1) and 1-MCP (10μLL^-1), an ethylene action inhibitor. In fruits attached to or detached from the tree, a slight increase in ethylene production was detected at the yellow stage, but the respiration rate declined progressively during ripening. Accumulation of transcripts of ethylene biosynthetic genes did not correlate with changes in ethylene production, since the maximum accumulation of ACS1 and ACO1 mRNA was detected in fully coloured fruits. Expression of ethylene receptor and signaling genes followed a different pattern in peel and pulp tissues. After fruit detachment and incubation at 20°C for up to 6days, ACS1 mRNA slightly increased, ACO1 experienced a substantial increment and ACO2 declined. In the peel, these changes were advanced by exogenous ethylene and partially inhibited by 1-MCP. In the pulp, 1-MCP repressed most of the changes in the expression of biosynthetic genes, while ethylene had almost no effects. Expression of ethylene perception and signaling genes was barely affected by ethylene or 1-MCP. Collectively, a differential transcriptional regulation of ethylene biosynthetic genes operates in peel and pulp, and support the notion of non-climacteric ripening in loquat fruits. Ethylene action, however, appears to be required to sustain or maintain the expression of specific genes.

Complete plastid genome of Eriobotrya japonica (Thunb.) Lindl and comparative analysis in Rosaceae

Eriobotrya japonica (Thunb.) Lindl (loquat) is an evergreen Rosaceae fruit tree widely distributed in subtropical regions. Its leaves are considered as traditional Chinese medicine and are of high medical value especially for cough and emesis. Thus, we sequenced the complete plastid genome of E. japonica to better utilize this important species. The complete plastid genome of E. japonica is 159,137 bp in length, which contains a typical quadripartite structure with a pair of inverted repeats (IR, 26,326 bp) separated by large (LSC, 89,202 bp) and small (SSC, 19,283 bp) single-copy regions. The E. japonica plastid genome encodes 112 unique genes which consist of 78 protein-coding genes, 30 tRNA genes and 4 rRNA genes. Gene structure and content of E. japonica plastid genome are quite conserved and show similarity among Rosaceous species. Five large indels are unique to E. japonica in comparison with Pyrus pyrifolia and Prunus persica, which could be utilized as molecular markers. A total of 72 simple sequence repeats (SSRs) were detected and most of them are mononucleotide repeats composed of A or T, indicating a strong A or T bias for base composition. The Ka and Ks ratios of most genes are lower than 1, which suggests that most genes are under purifying selection. The phylogenetic analysis described the evolutionary relationship within Rosaceae and fully supported a close relationship between E. japonica and P. pyrifolia.

Benzenoid biosynthesis in the flowers of Eriobotrya japonica: molecular cloning and functional characterization of p-methoxybenzoic acid carboxyl methyltransferase

p -Methoxybenzoic acid carboxyl methyltransferase (MBMT) was isolated from loquat flowers. MBMT displayed high similarity to jasmonic acid carboxyl methyltransferases, but exhibited high catalytic activity to form methyl p -methoxybenzoate from p -methoxybenzoic acid. Volatile benzenoids impart the characteristic fragrance of loquat (Eriobotrya japonica) flowers. Here, we report that loquat produces methyl p-methoxybenzoate, along with other benzenoids, as the flowers bloom. Although the adaxial side of flower petals is covered with hairy trichomes, the trichomes are not the site of volatile benzenoid formation. Here we identified four carboxyl methyltransferase (EjMT1 to EjMT4) genes from loquat and functionally characterized EjMT1 which we found to encode a p-methoxybenzoic acid carboxyl methyltransferase (MBMT); an enzyme capable of converting p-methoxybenzoic acid to methyl p-methoxybenzoate via methylation of the carboxyl group. We found that transcript levels of MBMT continually increased throughout the flower development with peak expression occurring in fully opened flowers. Recombinant MBMT protein expressed in Escherichia coli showed the highest substrate preference toward p-methoxybenzoic acid with an apparent K m value of 137.3 µM. In contrast to benzoic acid carboxyl methyltransferase (BAMT) and benzoic acid/salicylic acid carboxyl methyltransferase, MBMT also displayed activity towards both benzoic acid and jasmonic acid. Phylogenetic analysis revealed that loquat MBMT forms a monophyletic group with jasmonic acid carboxyl methyltransferases (JMTs) from other plant species. Our results suggest that plant enzymes with same BAMT activity have evolved independently.

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.

Loquat (Eriobotrya japonica) leaf extract inhibits the growth of MDA-MB-231 tumors in nude mouse xenografts and invasion of MDA-MB-231 cells

BACKGROUND/OBJECTIVES

The present study was conducted to examine the inhibitory effect of loquat leaves on MDA-MB-231 cell proliferation and invasion.

MATERIALS/METHODS

Female athymic nude mice were given a subcutaneous (s.c.) inoculation of MDA-MB-231 cells and randomly grouped to receive a s.c. injection of either 500 mg/kg ethanol, water extract or vehicle five times a week. Tumor growth, mitotic rate and necrosis were examined. MDA-MB-231 cells were cultured with DMSO or with various concentrations of loquat water or ethanol extract. Proliferation, adhesion, migration, invasion and matrix metalloproteinase (MMP) activity were examined.

RESULTS

Tumor growth of xenograft nude mouse was significantly reduced by loquat extracts. The results of mitotic examination revealed that loquat extracts reduced tumor cell division. Both ethanol and water extracts significantly inhibited MDA-MB-231 cell proliferation. The protein expression of ErbB3 was significantly down-regulated by loquat leaf extracts. Loquat leaf extracts increased apoptosis of MDA-MB-231 cells following 24 hour incubation and the ethanol extract was more potent in inducing apoptosis than the water extract. Furthermore, loquat extracts inhibited adhesion, migration and invasion of MDA-MB-231 cells. MMP activity was significantly inhibited by loquat extracts.

CONCLUSION

Our results show that extracts of loquat inhibit the growth of tumor in MDA-MB-231 xenograft nude mice and the invasion of human breast cancer cells, indicating the inhibition of tumor cell proliferation and invasion.

Activator- and repressor-type MYB transcription factors are involved in chilling injury induced flesh lignification in loquat via their interactions with the phenylpropanoid pathway

Lignin biosynthesis and its transcriptional regulatory networks have been studied in model plants and woody trees. However, lignification also occurs in some fleshy fruit and has rarely been considered in this way. Loquat ( Eriobotrya japonica ) is one such convenient tissue for exploring the transcription factors involved in regulating fruit flesh lignification. Firmness and lignin content of 'Luoyangqing' loquat were fund to increase during low-temperature storage as a typical symptom of chilling injury, while heat treatment (HT) and low-temperature conditioning (LTC) effectively alleviated them. Two novel EjMYB genes, EjMYB1 and EjMYB2, were isolated and were found to be localized in the nucleus. These genes responded differently to low temperature, with EjMYB1 induced and EjMYB2 inhibited at 0 °C. They also showed different temperature responses under HT and LTC conditions, and may be responsible for different regulation of flesh lignification at the transcriptional level. Transactivation assays indicated that EjMYB1 and EjMYB2 are a transcriptional activator and repressor, respectively. EjMYB1 activated promoters of both Arabidopsis and loquat lignin biosynthesis genes, while EjMYB2 countered the inductive effects of EjMYB1. This finding was also supported by transient overexpression in tobacco. Regulation of lignification by EjMYB1 and EjMYB2 is likely to be achieved via their competitive interaction with AC elements in the promoter region of lignin biosynthesis genes such as Ej4CL1.

Effect of MeJA treatment on polyamine, energy status and anthracnose rot of loquat fruit

The effect of methyl jasmonate (MeJA) on changes in polyamines content and energy status and their relation to disease resistance was investigated. Freshly harvested loquat fruit were treated with 10 μmol l(-1) MeJA and wound inoculated with Colletotrichum acutatum spore suspension (1.0 × 10(5) spores ml(-1)) after 24h, and then stored at 20 °C for 6 days. MeJA treatment significantly reduced decay incidence. MeJA treated fruit manifested higher contents of polyamines (putrescine, spermidine and spermine) compared with the control fruit, during storage. MeJA treatment also maintained higher levels of adenosine triphosphate, and suppressed an increase in adenosine monophosphate content in loquat fruit. These results suggest that MeJA treatment may inhibit anthracnose rot by increasing polyamine content and maintaining the energy status.