Loquat Trees Research Articles

Genomic Survey of LRR-RLK Genes in Eriobotrya japonica and Their Expression Patterns Responding to Environmental Stresses.

The impact of global warming is increasing and thus exacerbating environmental stresses that affect plant yield and distribution, including the Eriobotrya japonica Lindl (Loquat tree). Eriobotrya japonica, a member of the Rosaceae family, is valued not only for its nutritious fruit but also for its medicinal purposes, landscape uses, and other pharmacological benefits. Nonetheless, the productivity of Eriobotrya japonica has raised a lot of concern in the wake of adverse environmental conditions. Understanding the characteristics of the LRR-RLK gene family in loquat is crucial, as these genes play vital roles in plant stress responses. In this study, 283 LRR-RLK genes were identified in the genome of E. japonica that were randomly positioned on 17 chromosomes and 24 contigs. The 283 EjLRR-RLK proteins clustered into 21 classes and subclasses in the phylogenetic analysis based on domain and protein arrangements. Further explorations in the promoter regions of the EjLRR-RLK genes showed an abundance of cis-regulatory elements that functioned in growth and development, phytohormone, and biotic and abiotic responses. Most cis-elements were present in the biotic and abiotic responses suggesting that the EjLRR-RLK genes are invested in regulating both biotic and abiotic stresses. Additional investigations into the responses of EjLRR-RLK genes to abiotic stress using the RT-qPCR revealed that EjLRR-RLK genes respond to abiotic stress, especially heat and salt stresses. Particularly, EjapXI-1.6 and EjapI-2.5 exhibited constant upregulation in all stresses analyzed, indicating that these may take an active role in regulating abiotic stresses. Our findings suggest the pivotal functions of EjLRR-RLK genes although additional research is still required. This research aims to provide useful information relating to the characterization of EjLRR-RLK genes and their responses to environmental stresses, establishing a concrete base for the following research.

Two FT genes synergistically regulate the reproductive transition of loquat

Unlike annual flowering plants that exhibit a single reproductive cycle encompassing vegetative growth, flowering, and senescence within a single year, perennial woody trees undergo a transition between vegetative and reproductive growth every year after a long juvenile phase. Most woody fruit trees bloom when it turns warm in spring, and the fruit ripens in summer or autumn. However, as a member of the Maloideae subfamily, the loquat tree blooms in the cold autumn and winter, and the fruit matures in the spring. To explore the regulatory mechanism of loquat flowering, we characterized two FLOWERING LOCUS T homologous genes in loquat, EjFT1 and EjFT2. qRT-PCR results revealed that EjFT1 and EjFT2 exhibited nearly opposite expression patterns in various tissues. EjFT1 was mainly expressed in young tissues; EjFT2 was mainly expressed in mature leaves, open flowers, and fruits. EjFT2 exhibited an obvious circadian rhythm and was regulated by EjCO. After the trees were exposed to short-day conditions or sprayed with exogenous GA3, the expression of EjFT2 was strongly inhibited, and the loquat tree did not produce floral buds. Furthermore, the yeast two-hybrid, bimolecular fluorescence complementation, and Dual-luciferase assay experiments revealed that both EjFT1 and EjFT2 interacted with EjFD, with the EjFT2-EjFD protein complex enhancing the activity of EjAP1-1 and EjAP1-2 promoters, while EjFT1-EjFD inhibited the activity of the EjAP1-1 promoter. Protein structural analysis of EjFT1 and EjFT2 suggested that differences in amino acid residues at Val123/Leu123, Ser157/Ala157, and Val158/Ala158 may be the reason for their functional differences. Our results showed that EjFT1 and EjFT2 may cooperatively regulate the floral bud differentiation of loquat by competitively binding with EjFD. EjFT2 regulates the onset of loquat floral bud differentiation by responding to photoperiod and gibberellin signals, while EjFT1 is involved in the vegetative growth of loquat. These findings provide important clues for the investigation of the regulatory mechanism of loquat flowering and advance the exploration into the multiple roles of FT homologous genes in regulating the reproductive transformation and vegetative growth of flowering plants.

Characterization of Erwinia amylovora causing Twig Blight of Loquat Tree in Loquat Growing Areas of Punjab and KPK, Pakistan

Characterization of Erwinia amylovora causing Twig Blight of Loquat Tree in Loquat Growing Areas of Punjab and KPK, Pakistan

First Report of Fusarium luffae Causing Leaf Blight on Loquat in Eastern China.

During May-June 2021 and 2022, leaf blight symptoms were observed on loquat leaves (Eriobotrya japonica cv. 'Mogi') in Jiangsu Province (Xuzhou municipality, 117.17° E, 34.13° N) in China. Approximately 10% of the leaves on the two hundred trees studied in a six-year-old loquat orchard exhibited round lesions that changed from light yellow to reddish-brown in 8-10 days. Approximately 3% of the infected leaves exhibited numerous lesions that coalesced, leading to expansive blighted areas. Twenty-five samples of symptomatic tissue, approximately 0.2 cm2 in size, were collected in May 2022 from five different trees (five samples per tree), sterilized in 2% NaOCl for 1 min, washed twice with sterilized ddH2O, and incubated at 26°C for 5 days on PDA medium containing 50 µg/mL chloramphenicol. Six isolates were obtained via single spore isolation. ITS (OQ954852-OQ954857), TUB2 (OQ968488-OQ968493), EF1-α (OQ971890-OQ971895), RPB1 (OQ971896-OQ971901), and RPB2 (OR037266-OR037271) genes were amplified using the ITS1/ITS4, T1/T22, EF1-728F/EF1-986R, RPB1-R8/RPB1-F5, and fRPB2-7CF/fRPB2-11aR primers, respectively (O'Donnell et al. 2010). The species was identified using the Fusarioid ID database (Crous et al. 2021), revealing that all obtained isolates showed high homology to representative F. luffae strains. Upon combining the ITS, TUB2, EF1-α, RPB1, and RPB2 sequences, the isolates showed 99.42%-97.85% and 99.59%-98.10% identity to F. luffae CGMCC 3.19497 (ex-type strain) and NRRL 32522, respectively. A molecular phylogenetic tree was constructed using MEGA X, with a selection of representative Fusarium strains. Microscope observations showed septate mycelium, microconidia (6.86 ± 0.91 µm length, 1.67 ± 0.24 µm width, containing 1 septum; number of observations = 21), fusiform macroconidia (15.88 ± 1.43 µm length, 1.66 ± 0.24 µm width, containing 1 septum; number of observations = 45), and linear chlamydospores (79.36 ± 28.36 µm length, 12.03 ± 3.37 µm width; number of observations = 152). These observations are consistent with the morphology of F. luffae (Wang et al. 2019). All isolates exhibited identical morphological characteristics. All isolates were evaluated for pathogenicity in vivo using healthy non-detached loquat leaves. A total of 15 leaves from 5 different three-month-old 'Mogi' loquat trees were used for each isolate. Experiments were performed three times. A suspension of 1 × 106 spores/mL obtained from a seven-day-old colony (10 mL per 15 leaves), was sprayed on non-wounded leaves for inoculation. Sterilized ddH2O was used in the control experiment. Inoculated trees were stored at 26°C and 70% relative humidity for four days. Leaf blight symptoms were observed in all inoculated leaves, and the symptoms were observed in all repeated trials. The pathogen was recovered, and its identity was confirmed by ITS sequencing and morphological analysis, fulfilling Koch's postulates. In recent years, F. luffae has been reported to cause fruit rot on muskmelon, flower rot on kiwifruit, soybean pod rot, and leaf spot on cherry in China (Yu et al. 2022; Zhang et al. 2022; Zhao et al. 2022; Zhou et al. 2022), demonstrating the host promiscuity of this pathogen. Although F. solani has been identified as the causal agent of root rot and fruit rot on loquat (Abbas et al. 2017; Wu et al. 2021), this is the first report of F. luffae causing leaf blight on loquat worldwide. This report will help to understand the pathogens affecting loquat orchards in China.

Loquat, a non-native plant in Türkiye, is a key seasonal host in the life cycle of Thrips hawaiiensis (Morgan, 1913) (Thysanoptera: Thripidae)

The Hawaiian flower thrips, Thrips hawaiiensis (Morgan, 1913) (Thysanoptera: Thripidae) is an important pest of several fruit crops in Türkiye’s Mediterranean region, one of the world’s major citrus-growing regions. In this study, the population fluctuation of T. hawaiiensis and other thrips species was investigated in citrus orchards, weeds, and nearby loquat trees. Results showed significant differences in populations of T. hawaiiensis among citrus varieties. The highest population density and damage ratio of T. hawaiiensis among citrus species were recorded in lemon variety (Kütdiken). Thrips hawaiiensis was detected on Daucus carota L. and Amaranthus albus L. among weeds as well as on flowers of loquat in the sampling area. The life cycle of T. hawaiiensis switched seasonally among citrus, weed, and loquat host plants. In addition, Melanthrips pallidior (Priesner, 1919) was the predominant species on weeds in the sampling area. These data suggest that T. hawaiiensis populations may be affected by climatic variations and hosts in and around the citrus orchard. The results are important in optimizing thrips monitoring and management strategies in citrus.

Quiescent Infection of Flowers by the Causal Agents of Loquat Fruit Rot, Neopestalotiopsis sp. and Pestalotiopsis sp.

Loquat fruit rot, caused by Pestalotiopsis sensu lato, is a key problem for loquat producers in Nagasaki Prefecture, the area with the highest loquat fruit production in Japan. In a previous study, it was postulated that fruit rot pathogens latently infect flowers, with the corresponding disease symptoms occurring in wounded fruits. To reveal whether the pathogens responsible for the development of fruit rot disease are found in the asymptomatic flowers and immature fruits of loquat trees, we sprayed a conidial suspension of nitrate-nonutilizing mutants, containing strains derived from pathogenic Neopestalotiopsis sp. (TAP18N004) and Pestalotiopsis sp. (TAP18N010), onto the flowers of “Mogi” and “Nagasaki-wase” trees. Both inoculated mutants were reisolated using selective media (minimal media with chlorate) from the part of the asymptomatic immature fruit that includes the flower apex. Symptoms were observed in the mature fruits of both cultivars, and mutants were specifically detected in the symptomatic tissues of all rotted fruits. Additionally, all reisolated mutants were reconfirmed by assessing corresponding nitrate auxotrophy characteristics. Thus, it was revealed that both fruit rot pathogens that latently infect loquat flowers can cause fruit rot after maturation. [Formula: see text] The author(s) have dedicated the work to the public domain under the Creative Commons CC0 “No Rights Reserved” license by waiving all of his or her rights to the work worldwide under copyright law, including all related and neighboring rights, to the extent allowed by law, 2023.

Dried Loquat Fruit Extract Containing Chlorogenic Acid Prevents Depressive-like Behaviors Induced by Repeated Corticosteroid Injections in Mice.

Eriobotrya japonica (loquat tree) has been used in traditional medicine to treat respiratory ailments, inflammation, and skin diseases; however, its potential antidepressant-like effects have not been extensively investigated. In this study, we evaluated the antidepressant-like effects of E. japonica fruit extract (EJFE) in a mouse model of corticosterone (CORT)-induced depression. An HPLC analysis revealed that chlorogenic acid (CGA) is the major compound in EJFE. Male ICR mice (5weeks-old) were injected with CORT (40 mg/kg, intraperitoneally) once daily for 21 days to induce depressive-like behaviors. Various behavioral tests, including the open field test, rotarod test, elevated plus maze (EPM), passive avoidance test (PAT), tail suspension test (TST), and forced swim test (FST), were conducted 1 h after the oral administration of EJFE at different doses (30, 100, and 300 mg/kg) and CGA (30 mg/kg). High-dose EJFE and CGA significantly alleviated CORT-induced depressive-like behaviors, as indicated by the reduced immobility times in the TST and FST. A decrease in the step-through latency time in the PAT, without an effect on locomotor activity, suggested an improvement in cognitive function. Moreover, EJFE- and CGA-treated mice exhibited significantly reduced anxiety-like behaviors in the EPM. Our results imply the promising potential of EJFE containing CGA as a therapeutic candidate for depression.

Exogenously applied zinc improves sugar-acid profile of loquat (Eriobotrya japonica Lindl.) by regulating enzymatic activities and expression of their metabolism-related genes

Soluble sugars and organic acids are the most abundant components in ripe fruits, and they play critical roles in the development of fruit flavor and taste. In this study, loquat trees were sprayed with 0.1, 0.2 and 0.3% zinc sulphate. The contents of soluble sugars and organic acids were determined using HPLC-RID and UPLC-MS, respectively. The activities of key enzymes involved in sugar-acid metabolism were measured and expression profiling of related genes was done using RT-qPCR. The results revealed that 0.1% zinc sulphate was a promising treatment among other Zn applications with respect to the increased levels of soluble sugars and decreased acid contents in loquats. Correlation analysis showed that the enzymes i.e., SPS, SS, FK, and HK were may be involved in the regulation of fructose and glucose metabolism in the fruit pulp of loquat. While, the activity of NADP-ME showed negative and NAD-MDH showed a positive correlation with malic acid content. Meanwhile, EjSPS1-4, EjSS2-4, EjHK1-3, and EjFK1-6 may play an important role in soluble sugar metabolism in the pulp of loquat fruits. Similarly, EjPEPC2, EjPEPC3, EjNAD-MDH1, EjNAD-MDH3-5, EjNAD-MDH6 and EjNAD-MDH13 may have a vital contribution to malic acid biosynthesis in loquat fruits. This study provides new insights for future elucidation of key mechanisms regulating soluble sugars and malic acid biosynthesis in loquats.

Paramicrosphaeropsis eriobotryae sp. nov., a new agent of loquat canker in Iran

AbstractLoquat (Eriobotrya japonica) is a subtropical evergreen plant, important in terms of both horticulture and green space in the urban environment. In recent years, symptoms of branch and trunk canker, dieback and decline have been observed in the main cultivation areas of this tree in Iran. To study the aetiology of loquat canker in Fars Province, branches and trunks of loquat trees with disease symptoms were sampled from 2018 to 2019. Several isolates of an unknown Paramicrosphaeropsis species (Didymellaceae, Pleosporales, Dothideomycetes) were recovered from the trunks and branches of infected loquat trees. Phylogenetic analysis of the isolates based on a multigene phylogeny of the ribosomal internal transcribed spacer (ITS), partial β‐tubulin gene (tub2) and the second‐largest subunit of RNA polymerase II (rpb2) loci revealed that the isolates belonged to a new taxon, Paramicrosphaeropsis eriobotryae sp. nov. Pathogenicity tests revealed that this species was able to cause canker, trunk flaking, dieback, decline, leaf yellowing, defoliation and growth reduction in loquat trees. A host range evaluation on detached branches of some important horticultural trees occurring adjacent to loquat tree orchards of Fars Province showed that P. eriobotryae might have a broader host range, as it was also able to infect almond and olive trees.

First Report of Aspergillus Leaf Spot on Loquat (Eriobotrya japonica) Caused by Aspergillus fumigatus in Iraq

Leaf spots were noticed commonly on loquat trees in Alhussiania city, Karbala Province, Iraq. The associated fungus was isolated and identified as Aspergillus fumigatus based on the morphology (cultural and microscopic features) and molecular analysis (sequence of internal transcribed spacer rDNA). The pathogenicity of isolated fungus was confirmed through Koch’s postulates that were implemented by comparing the disease symptoms with those of naturally appeared and re-isolated from the inoculated leaves and re-identified. To best of our knowledge, this is the first record of A. fumigatus as causative agent of leaf spot on loquat (E. japonica) tree in Iraq and worldwide.

Sorbitol induces flower bud formation via the MADS-box transcription factor EjCAL in loquat.

Sorbitol is an important signaling molecule in fruit trees. Here, we observed that sorbitol increased during flower bud differentiation (FBD) in loquat (Eriobotrya japonica Lindl.). Transcriptomic analysis suggested that bud formation was associated with the expression of the MADS-box transcription factor (TF) family gene, EjCAL. RNA fluorescence in situ hybridization showed that EjCAL was enriched in flower primordia but hardly detected in the shoot apical meristem. Heterologous expression of EjCAL in Nicotiana benthamiana plants resulted in early FBD. Yeast-one-hybrid analysis identified the ERF12 TF as a binding partner of the EjCAL promoter. Chromatin immunoprecipitation-PCR confirmed that EjERF12 binds to the EjCAL promoter, and β-glucuronidase activity assays indicated that EjERF12 regulates EjCAL expression. Spraying loquat trees with sorbitol promoted flower bud formation and was associated with increased expression of EjERF12 and EjCAL. Furthermore, we identified EjUF3GaT1 as a target gene of EjCAL and its expression was activated by EjCAL. Function characterization via overexpression and RNAi reveals that EjUF3GaT1 is a biosynthetic gene of flavonoid hyperoside. The concentration of the flavonoid hyperoside mirrored that of sorbitol during FBD and exogenous hyperoside treatment also promoted loquat bud formation. We identified a mechanism whereby EjCAL might regulate hyperoside biosynthesis and confirmed the involvement of EjCAL in flower bud formation in planta. Together, these results provide insight into bud formation in loquat and may be used in efforts to increase yield.

Sugar and acid profile of loquat (Eriobotrya japonica Lindl.), enzymes assay and expression profiling of their metabolism-related genes as influenced by exogenously applied boron.

Soluble sugars and organic acids are the most abundant components in ripe fruits, and they play critical roles in the development of fruit flavor and taste. Some loquat cultivars have high acid content which seriously affect the quality of fruit and reduce the value of commodity. Consequently, studying the physiological mechanism of sugar-acid metabolism in loquat can clarify the mechanism of their formation, accumulation and degradation in the fruit. Minerals application has been reported as a promising way to improve sugar-acid balance of the fruits. In this study, loquat trees were foliar sprayed with 0.1, 0.2 and 0.3% borax, and changes in soluble sugars and organic acids were recorded. The contents of soluble sugars and organic acids were determined using HPLC-RID and UPLC-MS, respectively. The activities of enzymes responsible forthe metabolism of sugarsand acids were quantified and expressions of related genes were determined using quantitative real-time PCR. The results revealed that 0.2% borax was a promising treatment among other B applications for the increased levels of soluble sugars and decreased acid contents in loquats. Correlation analysis showed that the enzymes i.e., SPS, SS, FK, and HK were may be involved in the regulation of fructose and glucose metabolism in the fruit pulp of loquat. While the activity of NADP-ME showed negative and NAD-MDH showed a positive correlation with malic acid content. Meanwhile, EjSPS1, EjSPS3, EjSS3, EjHK1, EjHK3, EjFK1, EjFK2, EjFK5, and EjFK6 may play an important role in soluble sugars metabolism in fruit pulp of loquat. Similarly, EjPEPC2, EjPEPC3, EjNAD-ME1, EjNAD-MDH1, EjNAD-MDH5-8, EjNAD-MDH10, and EjNAD-MDH13 may have a vital contribution to malic acid biosynthesis in loquat fruits. This study provides new insights for future elucidation of key mechanisms regulating soluble sugars and malic acid biosynthesis in loquats.

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

BackgroundBud 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.ResultsSVP-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.ConclusionsPhylogenetic, 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.

Comparative faunistic analysis of mite species on neglected and conventional pome fruit trees in Turkey

The paper presents the comparative faunistic analysis of leaf inhabiting mite species on neglected and conventionally grown pome fruit trees in Turkey as well as their diversity and distributions. For this purpose, twelve sampling areas were chosen in the Ordu region of Turkey. The study was carried out on four fruit tree species, apple (Malus domestica), pear (Pyrus communis), quince (Cydonia oblonga), and loquat (Eriobotrya japonica), between 2014 and 2019. In the study, a total of 42 mite species were identified from 12 families belonging to two orders. 92.43% of all species were found on the neglected trees, while 7.57% were reported in the conventional orchards. Among phytophagous mites, Cenopalpus pulcher on the neglected trees and Amphitetranychus viennensis in the conventional orchards showed the greatest overall constancy. The most abundant and common predatory species were Phytoseius finitimus on the neglected trees and Transeius wainsteini in the conventional orchards. A high faunistic similarity was found between the conventionally grown apple fruit trees and neglected apple, pear, quince, loquat trees. Considering together predatory and tetranychoid mites, the highest interspecific association index was revealed for the pair T. wainsteini -- C. pulcher. Additionally, the pair Z. mali -- T. wainsteini within the predatory mites and A. viennensis -- C. pulcher within the tetranychoid mites had the highest index of association.

Declining abundance of pollinating insects drives falls in loquat (Eriobotrya japonica) fruit yields in the Pothwar region of Pakistan

Insects perform numerous vital ecosystem services, so widespread reports of insect declines are of considerable concern. However, there are huge knowledge gaps with regard to the extent and scale of insect declines, with most studies being from Europe and North America and very few long-term data sets on insect population change in Asia, Africa or South America. The current study describes trends in abundance of insect pollinators visiting loquat (Eriobotrya japonica) over 13 years (2006–2018) in ten widely-spaced orchards in the Pothwar region of Pakistan. Results reveal a significant and concerning decline of 89.9% in overall abundance of flower-visitors across the study period. All pollinator species declined; for example numbers of Apis dorsata fell by 97%, A. mellifera by 96%, A. cerana by 93%, and Bombus haemorrhoidalis by 84%. Declines were non-linear, being most rapid in 2006–2009. In parallel, the average yield per loquat tree fell by 61%; sugar and organic acid content also declined. Total flower-visiting insect abundance was a strong predictor of crop yield and quality over time and across sites, while pollinator species richness was less powerful. Trees that were given supplemental pollination by caging them with small honeybee colonies during flowering showed no decrease in yield or fruit quality. These results indicate that declines in populations of wild pollinators are negatively impacting loquat production and the livelihood of the small farmers of the area. Further research to identify the cause of these insect declines is urgently needed, alongside development of conservation strategies for pollinators in this region.

Stilbocrea banihashemiana sp. nov. a New Fungal Pathogen Causing Stem Cankers and Twig Dieback of Fruit Trees.

Stem cankers and twig dieback were the most serious disease of fig (Ficus carica) and loquat (Eriobotrya japonica) noticed in a survey of fruit tree orchards in the Fars Province, Iran. Isolates of Bionectriaceae were consistently recovered from symptomatic fig and loquat trees. Phylogenetic analyses of multiple nuclear loci, internal transcribed spacer regions (ITS) of rDNA, RNA polymerase II subunit 2 (rpb2), and translation elongation factor 1-α (tef1), combined with morphological observations, revealed that isolates could be referred to a still unknown taxon, which was formally described as Stilbocrea banihashemiana sp. nov. Phylogenetically, isolates from fig and loquat trees clustered in a well-supported monophyletic group within the Stilbocrea clade of Bionectriaceae, closely related to S. walteri. Stilbocrea banihashemiana sp. nov. was characterized by the lack of stilbella-like asexual structure in both natural substrates and pure cultures and produced two morphologically distinct types of conidia, globose and cylindrical, formed on short and long simple phialides. In pathogenicity tests, S. banihashemiana sp. nov. induced stem cankers in both fig and loquat, wood discoloration in fig and twig dieback in loquat. Pathogenicity tests also showed that the potential host range of this novel pathogen includes other economically relevant horticultural trees.

Effect of insecticides on the larvae of loquat psyllid, <i>Cacopsylla biwa</i> Inoue

The toxicities of various insecticides were determined using a bait twig method on larvae of the loquat psyllid, Cacopsylla biwa, collected from loquat trees in Wakayama Prefecture. Chlorpyrifos, malathion, methidathion, phenthoate, ethiprole, fenpropathrin, tralomethrin, acetamiprid, clothianidin, imidacloprid, and cartap were toxic and resulting in a corrected mortality rate >90%.

Effects of insecticides on adult loquat psyllids, <i>Cacopsylla biwa</i>

We investigated the toxicity of 31 insecticides to adult loquat psyllids, Cacopsylla biwa, collected from loquat trees in Wakayama Prefecture. Alanycarb, chlorpyrifos, malathion, methidathion, phenthoate, ethiprole, silafluofen, and cartap were toxic, resulting in a corrected mortality of more than 90%.

Effects of Solanum photeinocarpum and its post grafting generations straw on cadmium accumulation of loquat seedlings

ABSTRACT Herein, we prepared a pot experiment to explore the potential effects of cadmium (Cd) hyperaccumulator Solanum photeinocarpum and its post grafting generations straw on Cd accumulation in loquat seedlings. Two varieties (‘Dawuxing’ and ‘Chuanzao’) of loquat seedlings were planted in Cd-contaminated soil together with the straw of S. photeinocarpum (UG) and its post grafting generations with self-rooted grafting involving one S. photeinocarpum seedling (SG), self-rooted grafting involving two S. photeinocarpum seedling developmental stages (DG), and grafting on wild potato rootstock (PG). With the application of DG and PG straw, biomass of the root, stem, leaf, and shoot of loquat seedlings were slightly higher, whereas UG and SG straw had no apparent effects. DG and PG straw increased the Cd contents in various organs of loquat seedlings and elevated the Cd extractions in various organs of loquat seedlings to some extent while UG and SG had no apparent effects on that. These findings demonstrate that the straw of DG and PG can promote growth and increase the phytoremediation ability of loquat seedlings (not suitable for the resulting loquat tree), with PG as the best choice.

Removal of the main inflorescence to induce reflowering of loquat

Loquat (Eriobotrya japonica Lindl.) is an evergreen fruit tree species of the Rosaceae, and its unique flowering time greatly hinders its production. To explore the artificial regulation of loquat flowering time, we removed the main inflorescence (by cutting it) to induce reflowering. For different loquat tree cultivars with different stages, the inflorescence was removed by cutting the main floral axis at two alternative positions: the upper or the lower position beneath the inflorescence, and it was found that the proportion of reflowering resulting from removing the upper position of the main floral axis of yellow-flesh loquat cultivars during the full-bloom stage was the highest. In addition, compared with those of the normal-growing panicles, the number of flower buds and branch axes of the reflowering panicles decreased significantly after cutting. Importantly, these newly produced inflorescences flowered 2–4 months later than normal-growing inflorescences did, effectively prolonging both the flowering and fruiting time. In addition, qRT-PCR results showed that EjFT1, EjFT2, EjAP1–1 and EjAP1–2 were highly expressed in the floral axis. These findings highlighted a new method for extending the production cycle of loquat and provided a reference for the flowering regulation of loquat and other economically important fruit tree species.