scholarly journals Identification, Virulence and Fungicide Sensitivity of Colletotrichum gloeosporioides s.s. Responsible for Walnut Anthracnose Disease in China

Plant Disease ◽  
2020 ◽  
Vol 104 (5) ◽  
pp. 1358-1368 ◽  
Author(s):  
Qing-Hai Wang ◽  
Kun Fan ◽  
De-Wei Li ◽  
Chuan-Ming Han ◽  
Yong-Yun Qu ◽  
...  
Keyword(s):  
Colletotrichum Gloeosporioides ◽  
Phylogenetic Analyses ◽  
Juglans Regia ◽  
Population Diversity ◽  
Intraspecific Diversity ◽  
Effective Control ◽  
Maximal Effect ◽  
Fungicide Sensitivity ◽  
Geographic Regions ◽  
Walnut Leaves

Walnut (Juglans regia L.) is an economically important woody nut and edible oil tree all over the world. However, walnut production is limited by walnut anthracnose, which is a disastrous disease that causes significant yield losses. Studying the etiology of anthracnose on walnut and the pathogens’ virulence and sensitivities to fungicides would be beneficial for effective control. This study was conducted to identify the pathogen of walnut anthracnose and reveal the population diversity of pathogens through virulence, sensitivities to fungicides, and genetic variation. A total of 13 single-spore Colletotrichum isolates were collected from walnut anthracnose-diseased fruits and leaves from 13 walnut commercial orchards in Henan, Hubei, Shandong, and Shaanxi provinces in China. The isolates were identified as Colletotrichum gloeosporioides sensu stricto (s.s.) according to multilocus phylogenetic analyses (internal transcribed spacer, actin, glyceraldehyde-3-phosphate dehydrogenase, and chitin synthase), morphological as well as cultural characters, and pathogenicity. When the same walnut tissue was inoculated with different isolates, the disease lesion size was different. The results showed that the virulence of all isolates was considerably different, and the differences were not correlated with geographic origins. The virulence to walnut leaves and fruits inoculated with the same isolate was significantly different. Based on the virulence to walnut leaves and fruits, the 13 isolates were divided into three groups. Virulence of 69.2% of the isolates to walnut fruits was higher than that to leaves; 15.4% of isolates had no difference in pathogenicity, and the virulence to walnut leaves was higher for 15.4% of isolates. Tebuconazole, difenoconazole, flusilazole, and carbendazim inhibited the growth of fungal mycelia, and the concentration for 50% of maximal effect (EC50) values were 0.4 to 20.5, 0.6 to 2.6, 0.2 to 1.6, and 0.002 to 0.2 µg/ml, respectively, with average values of 6.5 ± 6.9, 1.5 ± 0.6, 0.9 ± 0.4, and 0.1 ± 0.05 µg/ml, respectively. All isolates were more sensitive to difenoconazole, flusilazole, and carbendazim than tebuconazole (P < 0.01). Isolate sensitivities to the same fungicide were different. Isolates SL-31 and TS-09 were the least sensitive to carbendazim and tebuconazole, respectively, and the resistance ratios were 87.3 and 51.6, respectively. Sensitivities to difenoconazole and flusilazole were largely consistent among all isolates, and the resistance ratios were from 1 to 4.6 and from 1 to 7, respectively. Therefore, difenoconazole and flusilazole could be chosen for disease control. The differences of pathogenicity and fungicide sensitivity were not correlated with geographic regions. These results indicated that there was high intraspecific diversity of populations in C. gloeosporioides s.s. that caused walnut anthracnose. For effective management, the targeted control strategy should be implemented based on the different geographic regions.

scholarly journals Fungicide Sensitivity and Phylogenetic Relationship of Anthracnose Fungi Isolated from Various Fruit Crops in Japan

Plant Disease ◽  
2006 ◽  
Vol 90 (4) ◽  
pp. 506-512 ◽  
Author(s):  
Wen-Hsin Chung ◽  
Hideo Ishii ◽  
Kumiko Nishimura ◽  
Masako Fukaya ◽  
Kazutaka Yano ◽  
...  
Keyword(s):  
Phylogenetic Relationship ◽  
Colletotrichum Gloeosporioides ◽  
Phylogenetic Analyses ◽  
Interspecific Variation ◽  
Fruit Crops ◽  
Fungicide Sensitivity ◽  
Genetic Groups ◽  
Molecular Phylogenetic ◽  
Relationship Of ◽  
The Relationship

Anthracnose diseases of fruit crops are mainly caused by Colletotrichum gloeosporioides and C. acutatum. In these Colletotrichum species, intra- and interspecific variation in fungicide sensitivity has been reported; however, the relationship between fungicide sensitivity and molecular phylogeny has not been analyzed. Fifty-one isolates from 10 fruit crops, acacia, and tea were tested for their sensitivities to thiophanate-methyl, diethofencarb, and iminoctadine-triacetate, and their internal transcribed spacer (ITS) and 5.8S regions of rDNA were analyzed. C. gloeosporioides isolates were divided into sensitive, less sensitive, intermediate resistant, or resistant to the three fungicides. In contrast, C. acutatum isolates were all less sensitive. In molecular phylogenetic analyses, C. gloeosporioides isolates fell into the same genetic group, whereas C. acutatum isolates were placed into two genetic groups. Although phylogenetic relationship was not closely related to fungicide sensitivity, the isolates of C. gloeosporioides most resistant to iminoctadine-triacetate were found in the same phylogenetic subgroup.

scholarly journals Morphometric and Molecular Diversity among Seven European Isolates of Pratylenchus penetrans

Plants ◽  
2021 ◽  
Vol 10 (4) ◽  
pp. 674
Author(s):  
Mesfin Bogale ◽  
Betre Tadesse ◽  
Rasha Haj Nuaima ◽  
Bernd Honermeier ◽  
Johannes Hallmann ◽  
...  
Keyword(s):  
Phylogenetic Analyses ◽  
Management Strategies ◽  
Ornamental Plants ◽  
Geographic Origin ◽  
Tail Length ◽  
Nematode Species ◽  
Intraspecific Diversity ◽  
Effective Control ◽  
Pratylenchus Penetrans ◽  
The Usa

Pratylenchus penetrans is an economically important root-lesion nematode species that affects agronomic and ornamental plants. Understanding its diversity is of paramount importance to develop effective control and management strategies. This study aimed to characterize the morphological and genetic diversity among seven European isolates. An isolate from the USA was included in the molecular analyses for comparative purposes. Morphometrics of the European P. penetrans isolates generally were within the range of the original descriptions for this species. However, multiple morphometric characteristics, including body length, maximum body width, tail length and length of the post-vulval uterine sac showed discrepancies when compared to other populations. Nucleotide sequence-based analyses revealed a high level of intraspecific diversity among the isolates. We observed no correlation between D2-D3 rDNA- and COXI-based phylogenetic similarities and geographic origin. Our phylogenetic analyses including selected GenBank sequences also suggest that the controversy surrounding the distinction between P. penetrans and P. fallax remains.

scholarly journals First Report of Leaf Spot Disease Caused by Colletotrichum gloeosporioides on Chinese Bean Tree in China

Plant Disease ◽  
2013 ◽  
Vol 97 (1) ◽  
pp. 138-138 ◽  
Author(s):  
B. Z. Fu ◽  
M. Yang ◽  
G. Y. Li ◽  
J. R. Wu ◽  
J. Z. Zhang ◽  
...  
Keyword(s):  
Leaf Spot ◽  
Colletotrichum Gloeosporioides ◽  
Disease Incidence ◽  
Phylogenetic Analyses ◽  
Morphological Characteristics ◽  
Leaf Spot Disease ◽  
First Report ◽  
Spot Disease ◽  
Rdna Its ◽  
Its Sequence Analysis

Chinese bean tree, Catalpa fargesii f. duciouxii (Dode) Gilmour, is an ornamental arbor plant. Its roots, leaves, and flowers have long been used for medicinal purposes in China. During July 2010, severe outbreaks of leaf spot disease on this plant occurred in Kunming, Yunnan Province. The disease incidence was greater than 90%. The symptoms on leaves began as dark brown lesions surrounded by chlorotic halos, and later became larger, round or irregular spots with gray to off-white centers surrounded by dark brown margins. Leaf tissues (3 × 3 mm), cut from the margins of lesions, were surface disinfected in 0.1% HgCl2 solution for 3 min, rinsed three times in sterile water, plated on potato dextrose agar (PDA), and incubated at 28°C. The same fungus was consistently isolated from the diseased leaves. Colonies of white-to-dark gray mycelia formed on PDA, and were slightly brown on the underside of the colony. The hyphae were achromatic, branching, septate, and 4.59 (±1.38) μm in diameter on average. Perithecia were brown to black, globose in shape, and 275.9 to 379.3 × 245.3 to 344.8 μm. Asci that formed after 3 to 4 weeks in culture were eight-spored, clavate to cylindrical. The ascospores were fusiform, slightly curved, unicellular and hyaline, and 13.05 to 24.03 × 10.68 to 16.02 μm. PCR amplification was carried out by utilizing universal rDNA-ITS primer pair ITS4/ITS5 (2). Sequencing of the PCR products of DQ1 (GenBank Accession No. JN165746) revealed 99% similarity (100% coverage) with Colletotrichum gloeosporioides isolates (GenBank Accession No. FJ456938.1, No. EU326190.1, No. DQ682572.1, and No. AY423474.1). Phylogenetic analyses (MEGA 4.1) using the neighbor-joining (NJ) algorithm placed the isolate in a well-supported cluster (>90% bootstrap value based on 1,000 replicates) with other C. gloeosporioides isolates. The pathogen was identified as C. gloeosporioides (Penz.) Penz. & Sacc. (teleomorph Glomerella cingulata (Stoneman) Spauld & H. Schrenk) based on the morphological characteristics and rDNA-ITS sequence analysis (1). To confirm pathogenicity, Koch's postulates were performed on detached leaves of C. fargesii f. duciouxii, inoculated with a solution of 1.0 × 106 conidia per ml. Symptoms similar to the original ones started to appear after 10 days, while untreated leaves remained healthy. The inoculation assay used three leaves for untreated and six leaves for treated. The experiments were repeated once. C. gloeosporioides was consistently reisolated from the diseased tissue. C. gloeosporioides is distributed worldwide causing anthracnose on a wide variety of plants (3). To the best of our knowledge, this is the first report of C. gloeosporioides causing leaf spots on C. fargesii f. duciouxii in China. References: (1) B. C. Sutton. Page 1 in: Colletotrichum: Biology, Pathology and Control. CAB International. Wallingford, UK, 1992. (2) T. J. White et al. Page 315 in: PCR Protocols: A Guide to Methods and Applications. Academic Press, San Diego, 1990. (3) J. Yan et al. Plant Dis. 95:880, 2011.

scholarly journals Optimization of the Extraction of Bioactive Compounds from Walnut (Juglans major 209 x Juglans regia) Leaves: Antioxidant Capacity and Phenolic Profile

Antioxidants ◽  
2019 ◽  
Vol 9 (1) ◽  
pp. 18 ◽  
Author(s):  
Adela Fernández-Agulló ◽  
Aída Castro-Iglesias ◽  
María Sonia Freire ◽  
Julia González-Álvarez
Keyword(s):  
Antioxidant Capacity ◽  
Antioxidant Activities ◽  
Juglans Regia ◽  
Ultra Performance Liquid Chromatography ◽  
Extraction Yield ◽  
Effect Of Temperature ◽  
Antioxidant Power ◽  
Linear Effect ◽  
Flight Mass Spectrometry ◽  
Walnut Leaves

This work studies the extraction of phenolic compounds from walnut leaves of the hybrid Juglans major 209 x Juglans regia based on extract antioxidant capacity. Once the solid/liquid ratio was selected (1/10 g/mL), by means of a Box-Benkhen experimental design, the influence of temperature (25–75 °C), time (30–120 min), and aqueous ethanol concentration (10–90%) on extraction yield and ferric reducing antioxidant power (FRAP), 2,2-diphenyl-1-picrylhydrazyl (DPPH), and 2,2’-azinobis-3-ethylbenzothiazoline-6-sulfonic acid (ABTS) antioxidant activities were analyzed. In all cases, the quadratic effect of % EtOH was the most significant, followed by the linear effect of temperature and, for most of the responses, the effect of time was almost negligible. Response surface analysis allowed to select the optimal extraction conditions: 75 °C, 120 min and 50% ethanol, which led to the following extract properties: extraction yield, 30.17%; FRAP, 1468 nmol ascorbic acid equivalents (AAE)/mg extract d.b.; DPPH, 1.318 mmol Trolox equivalents (TRE)/g extract d.b.; DPPH EC50, 0.11 mg/mL; ABTS, 1.256 mmol TRE/g extract (on dry basis) and ABTS EC50, 0.985 mg/mL. Quercetin 3-β-D-glucoside, neochlorogenic acid, and chlorogenic acid, in this order, were the main compounds identified in this extract by ultra-performance liquid chromatography coupled with electrospray ionization and time-of-flight mass spectrometry (UPLC/ESI-QTOF-MS), with various potential applications that support this valorization alternative for walnut leaves.

scholarly journals Avirulence gene based RFLP and rep-PCR distinguish the genetic variation of Xanthomonas oryzae pv. oryzae pathotypes in Bangladesh

2022 ◽  
Vol 9 (1) ◽  
pp. 29-40
Author(s):  
Mohammad Mahbubul Haque ◽  
Md. Mostafa Masud ◽  
Samrin Bashar ◽  
Mohammad Iqbal Hossain ◽  
Md. Zahangir Alam ◽  
...  
Keyword(s):  
Genetic Variation ◽  
Bacterial Blight ◽  
Phylogenetic Analyses ◽  
Control Measures ◽  
Avirulence Gene ◽  
Effective Control ◽  
Repeat Domain ◽  
Relationship Of ◽  
The Relationship ◽  
Pcr Techniques

Bacterial blight (BB) caused by X. oryzae pv. oryzae is one of the devastating diseases of rice mostly in Asia. Genomes of X. oryzae pv. oryzae is highly variable due to rearrangement of the large contents of transposable elements and dynamic changes of X. oryzae pv. oryzae population regulated efficiency of the control measures used for BB management of rice worldwide. In this study, genetic variation of X. oryzae pv. oryzae pathotypes of Bangladesh was studied using aviruelnce gene based RFLP and rep-PCR techniques aimed to formulate pathogen targeted effective control measures against BB of rice. Eight pathotypes of X. oryzae pv. oryzae field isolates were identified based on their reactions against 10 Near Isogenic Lines (NILs). Among eight pathotypes, pathotypes IV and V contained higher number of isolates which were 30.13% and 23.01% respectively while pathotype VIII revealed as minimum containing only 2.51% of total isolates. These eight pathotypes were studied for their genetic variation by RFLP using avrBs3 repeat domain as probe. The results conceded that Bangladeshi X. oryzae pv. oryzae strains seem carrying a minimum of two and maximum of nine avrBs3 family genes homologs. The resistance phenotype on IRBB7 and IRBB10 NILs also indicated presence of two major avrBs3 family genes viz. avrxa7 and avrXa10 in some pathotypes. Relationship of phylogenicity exhibited that X. oryzae pv. oryzae pathotypes assorted into two RFLP haplotypes as well as these haplotypes are largely distributed in Bangladesh. Phylogenetic analyses carried out by (REP, ERIC), rep-PCR and BOX depicted the presence of two main molecular haplotypes of X. oryzae pv. oryzae pathotypes. The relationship between pathotypes and molecular haplotypes of X. oryzae pv. oryzae in Bangladesh indicated that the same lineage possesses different pathotypes and different lineage possesses different pathotypes. The results indicated that eight different pathotypes might have originated from common inherited haplotypes with a wide genetic variation.

scholarly journals Phenotypic and molecular characterization of fluoroquinolone resistant Pseudomonas aeruginosa isolates in Palestine

2022 ◽  
Vol 82 ◽  
Author(s):  
G. Adwan ◽  
G. Omar
Keyword(s):  
Antimicrobial Agents ◽  
West Bank ◽  
Phylogenetic Analyses ◽  
Haplotype Diversity ◽  
Population Diversity ◽  
Control Measures ◽  
Clinical Samples ◽  
North West ◽  
The North ◽  
Medical Centers

Abstract Fluoroquinolones are important antimicrobial agents for the treatment of Pseudomonas infections. A total of 11 isolates of P. aeruginosa were collected from different clinical samples from different medical centers in the North West Bank-Palestine during 2017. In this study, resistance to fluoroquinolones and secretions of β-lactamases were detected by phenotypic methods, while presence of β-lactamase gene sequences and other virulence factors were detected by PCR technique. PCR product for gyrA, parC and parE genes were sequenced for further analyses. The phylogenetic analyses, population diversity indices and haplotypes determination were conducted using computer programs MEGA version 6, DnaSP 5.1001 and median-joining algorithm in the program Network 5, respectively. Results of this study showed that the MIC for ciprofloxacin and norfloxacin had a range of 32-256 µg/ml. In addition, all isolates carried either exoT or exoT and exoY genes, different β-lactamase genes and 82% of these isolates harbored class 1 integrons. Analyses of the gyrA, parC and parE sequences were found to be polymorphic, had high haplotype diversity (0.945-0.982), low nucleotide diversity (0.01225-0.02001) and number of haplotypes were 9 for each gyrA and parE genes and 10 haplotypes for parC gene. The founder haplotypes being Hap-1 (18%), Hap-2 (27.3%) and Hap-6 (9.1%) for gyrA, parC and parE genes, respectively. Two of ParE haplotypes were detected as indel haplotypes. The Median-joining- (MJ) networks constructed from haplotypes of these genes showed a star-like expansion. The neutrality tests (Tajima’s D test and Fu’s Fs test) for these genes showed negative values. Palestinian fluoroquinolone resistant P. aeruginosa strains showed high MIC level for fluoroquinolones, β-lactamase producers, carried type III secretion exotoxin-encoding genes, most of them had integrase I gene and had high level of mutations in QRDR regions in gyrA, parC and parE genes. All these factors may play an important role in the invasiveness of these strains and make them difficult to treat. Isolation of these strains from different medical centers, indicate the need for a strict application of infection control measures in Medical centers in the North West Bank-Palestine that aim to reduce expense and damage caused by P. aeruginosa infections. Molecular analyses showed that Palestinian fluoroquinolone resistant P. aeruginosa haplotypes are not genetically differentiated; however, more mutations may exist in these strains.

scholarly journals First Report of Anthracnose Caused by Colletotrichum gloeosporioides in Pumpkin in Trinidad

Plant Disease ◽  
2010 ◽  
Vol 94 (8) ◽  
pp. 1062-1062
Author(s):  
S. N. Rampersad
Keyword(s):  
Colletotrichum Gloeosporioides ◽  
Phylogenetic Analyses ◽  
Pcr Amplification ◽  
Positive Control ◽  
Universal Primers ◽  
Conidial Suspension ◽  
Specific Primers ◽  
First Report ◽  
Main Production ◽  
Species Specific

In Trinidad, pumpkin (Cucurbita pepo L. and C. moschata L.) is extensively grown for local and international export markets. In November 2008, symptoms of foliar chlorosis and necrosis were observed in 15 commercial pumpkin fields located in the main production areas of St. George East, Caroni, Victoria, and St. Patrick counties. Severely infected plants were unable to support fruit maturation, which resulted in yield loss. The pathogen was isolated from surface-sterilized tissues of symptomatic plants. Colonies on potato dextrose agar (PDA) were white to cream with gray spore masses in the center. Conidia were hyaline, cylindrical with rounded ends, aseptate, and measured 12.5 to 16.5 μm × 3.5 to 5.0 μm. PCR amplification was carried out with ITS4/5 universal primers (4) and species-specific primers, CgInt/ITS4 (1), using a positive control of Colletotrichum gloeosporioides (courtesy of D. Perez-Brito). Species-specific primers generated a single amplicon, ~450 bp long, which corresponded with the positive control. The ITS1 region (1) of pumpkin isolates (GenBank No. GU320190) was 100% identical to cognate sequences of C. gloeosporioides isolates (GenBank Nos. AY841136 and FJ624257). Phylogenetic analyses (MEGA 4 – Molecular Evolutionary Genetic Analysis Software version 4 for Windows) using the neighbor-joining (NJ) algorithm placed the pumpkin isolates in a well-supported cluster (>90% bootstrap value based on 1,000 replicates) with other C. gloeosporioides isolates. The tree was rooted with C. crassipes (GenBank No. AJ536230). The pathogen was similar to C. gloeosporioides (Penz.) Penz. & Sacc. (3). In pathogenicity tests, six plants (cv. Jamaican squash) for each of five isolates were spray inoculated to runoff with a conidial suspension (1.0 × 106 conidia/ml). Negative controls were sprayed with sterile distilled water. In repeated tests, plants were symptomatic of infection 7 days postinoculation. There were no symptoms on control plants. Koch's postulates were fulfilled with the reisolation of the pathogen from symptomatic leaf tissues. Anthracnose is a serious threat to cucurbit production; however, infection is not common in pumpkin and squash (2). To my knowledge, this is the first report of C. gloeosporioides causing widespread anthracnose infection in pumpkin in Trinidad. References: (1) A. E. Brown et al. Phytopathology 86:523, 1996. (2) G. Kelly. Acta Hortic. (ISHS) 731:479, 2007. (3) B. C. Sutton. Page 1 in: Colletotrichum: Biology, Pathology and Control. CAB International. Wallingford, UK, 1992. (4) T. J. White et al. Page 315 in: PCR Protocols: A Guide to Methods and Applications. Academic Press, San Diego, 1990.

scholarly journals Genome-wide identification and characterization of long non-coding RNAs conferring resistance to Colletotrichum gloeosporioides in walnut (Juglans regia)

2020 ◽  
Author(s):  
Shan Feng ◽  
Hongcheng Fang ◽  
Xia Liu ◽  
Yuhui Dong ◽  
Qingpeng Wang ◽  
...  
Keyword(s):  
Disease Resistance ◽  
Plant Disease Resistance ◽  
Molecular Mechanisms ◽  
Target Genes ◽  
Colletotrichum Gloeosporioides ◽  
Juglans Regia ◽  
Bioinformatic Analysis ◽  
Genome Wide ◽  
Phenylpropanoid Biosynthesis ◽  
Non Coding Rnas

Abstract Background: Walnut anthracnose caused by Colletotrichum gloeosporioides (Penz.) Penz. and Sacc. is an important walnut production problem in China. Although the long non-coding RNAs (lncRNAs) are important for plant disease resistance , the molecular mechanisms underlying resistance to C. gloeosporioides in walnut remain poorly understood.Results: The anthracnose-resistant F26 fruits from the B26 clone and the anthracnose-susceptible F423 fruits from the 4-23 clone of walnut were used as the test materials. Specifically, we performed a comparative transcriptome analysis of F26 and F423 fruit bracts to identify differentially expressed LncRNAs (DELs) at five time-points (tissues at 0 hpi, pathological tissues at 24 hpi, 48 hpi, 72 hpi, and distal uninoculated tissues at 120 hpi). Compared with F423, a total of 14525 DELs were identified, including 10645 upregulated lncRNAs and 3846 downregulated lncRNAs in F26. The number of upregulated lncRNAs in F26 compared to in F423 was significantly higher at the early stages of C. gloeosporioides infection. A total of 5 modules related to disease resistance were screened by WGCNA and the target genes of lncRNAs were obtained. Bioinformatic analysis showed that the target genes of upregulated lncRNAs were enriched in immune-related processes during the infection of C. gloeosporioides, such as activation of innate immune response, defense response to bacterium, incompatible interaction and immune system process, and enriched in plant hormone signal transduction, phenylpropanoid biosynthesis and other pathways. And 124 known target genes for 96 hub lncRNAs were predicted, including 10 known resistance genes. The expression of 5 lncRNAs and 5 target genes was confirmed by qPCR, which was consistent with the RNA-seq data.Conclusions: The results of this study provide the basis for future functional characterizations of lncRNAs regarding the C. gloeosporioides resistance of walnut fruit bracts.

scholarly journals First Report of Leaf Spot Caused by Colletotrichum fructicola on Myrica rubra in China

Plant Disease ◽  
2021 ◽  
Author(s):  
Shucheng Li ◽  
Liuhua Xiao ◽  
Fan Wu ◽  
Yinbao Wang ◽  
Mingshu Jia ◽  
...  
Keyword(s):  
Leaf Spot ◽  
Juglans Regia ◽  
Morphological Characteristics ◽  
Effective Control ◽  
Bootstrap Support ◽  
Sterile Water ◽  
First Report ◽  
Myrica Rubra ◽  
Initial Symptoms ◽  
Colletotrichum Fructicola

Myrica rubra is an important fruit tree with high nutritional and economic value, which is widely cultivated in multiple regions of China. In January 2021, an unknown disease which caused leaf spot with approximately 20% (n=100 investigated plants) of incidence was discovered on the leaves of M.rubra in Jiujiang City of Jiangxi Province (29.71° N, 115.97° E). The initial symptoms were small pale brown spots (1 to 2 mm diameter) on the leaves, which gradually expanded into round or irregular dark brown spots with the occurrence of the disease, and the lesion developed necrotic tissues in the center at later stages, eventually leading the leaves to chlorotic and wilted. Ten diseased leaves with typical symptoms were collected and the leaf tissue (5 × 5 mm) at junction of diseased and healthy portion were cut. The surfaces were disinfected with 75% ethanol for 45 s, 1% sodium hypochlorite for 1 min, and rinsed in sterile water for 3 times then transferred to potato dextrose agar (PDA) at 28 ± 1 ℃ for 3 days. Five fungal single isolates with similar morphology were purified from single spores. On PDA medium, the colonies initially appeared white with numerous aerial hyphae, and the center of the colony turned gray at later stages, less sporulation. While on modified czapek-dox medium (Peptone 3g, K2HPO4 1g, MgSO4·7H2O 0.5g, KCl 0.5g, FeSO4 0.01g, Maltose 30g, Agar 15g, Distilled water 1000 mL, pH=7.0), the mycelia of the colony were sparse and produced a large number of small bright orange particles (conidial masses). Conidia were single-celled, transparent, smooth-walled, 1-2 oil globule, cylindrical with slightly blunt rounded ends, 14.45-18.44 × 5.54-6.98 μm (av=16.27 μm × 6.19 μm, n=50) in size. These morphological characteristics of the pathogen were similar to the descriptions of Colletotrichum fructicola (Ruan et al, 2017; Yang et al, 2021). To further confirm the identity of the pathogen, genomic DNA from a representative isolate was extracted with DNA Extraction Kit (Yeasen, Shanghai, China), and the internal transcribed spacer (ITS), glyceraldehyde-3-phosphatedehydrogenase (GAPDH), calmodulin gene (CAL), actin (ACT) and chitin synthase 1 (CHS 1) were amplified by using the primers ITS1/ITS4 (Gardes et al, 1993), GDF/GDR (Templeton et al, 1992), CL1C/CL2C (Weir et al, 2012), ACT-512F/ACT-783R and CHS-79F/CHS-345R (Carbone et al, 1999), respectively. The PCR amplified sequences were submitted to GenBank (GenBank Accession No. ITS, MW740334; GAPDH, MW759805; CAL, MW759804; ACT, MW812384; CHS-1, MW759803) and aligned with GenBank showed 100% identity with C. fructicola (GenBank Accession No. ITS, MT355821.1 (546/546 bp); GAPDH, MT374664.1 (255/255 bp); CAL, MK681354.1 (741/741 bp); ACT, MT364655.1 (262/262 bp); CHS, MT374618.1 (271/271 bp)). Phylogenetic tree using the maximum likelihood methods with Kimura 2-parameter model and combined ITS-ACT-GAPDH-CHS-CAL concatenated sequences, bootstrap nodal support for 1000 replicates in MEGA7.0, revealed that the isolate was assigned to C. fructicola strain (ICMP 18581 and CBS 125397) (Yang et al. 2021) with 98% bootstrap support. Pathogenicities of were tested on fifteen healthy M. rubra plants (five for wounded inoculation, five for nonwounded inoculation, and five for controls) in the orchard. Twenty leaves were marked from each plant, and disinfected the surface with 75% ethanol. Ten μL spore suspension (1.0 × 106 conidia/ml) of each isolate from 7-day-old culture were inoculated on the surface of 20 needle-wounded and 20 nonwounded leaves, respectively. Healthy leaves were inoculated with sterile water as controls by the same method. All inoculated leaves were sprayed with sterile water and covered with plastic film to remained humidification. After 5 days, all the wounded leaves which were inoculated with C. fructicola showed similar symptoms to those observed on the original leaves. Symptoms of nonwounded leaves were milder than the wounded inoculated leaves, while control leaves remained healthy. Finally, the C. fructicola was re-isolated from the inoculated leaves. C. fructicola has been reported on Juglans regia, Peucedanum praeruptorum, Paris polyphylla var. Chinensis in China (Wang et al, 2017; Ma et al, 2020; Zhou et al, 2020). As far as we know, this is the first report of C. fructicola causing leaf spot on M.rubra in China. This result contributes to better understand the pathogens causing diseases of M.rubra in this region of China and develop effective control strategies.

scholarly journals The Mechanism of Foliar Zinc Absorption in Pistachio and Walnut

1999 ◽  
Vol 124 (3) ◽  
pp. 312-317 ◽  
Author(s):  
Qinglong Zhang ◽  
Patrick H. Brown
Keyword(s):  
Juglans Regia ◽  
Leaf Age ◽  
Absorption Capacity ◽  
Metabolic Inhibitors ◽  
Stable Isotope Labelling ◽  
Zn Uptake ◽  
Detached Leaves ◽  
Uptake Process ◽  
High Concentrations ◽  
Walnut Leaves

The characteristics and mechanisms of foliar Zn uptake and translocation in pistachio (Pistachio vera L.) and walnut (Juglans regia L.) were investigated using 68Zn labelling in both intact and detached leaves. Following washing, mature walnut and pistachio leaves retained 8% and 12% of the total Zn applied, respectively. About half of retained Zn (3.5% and 6.5% of total Zn respectively) was absorbed into the leaf and translocated outside the treated area. Leaf age affected the Zn absorption capacity of pistachio but not walnut. Immature pistachio leaves absorbed more Zn than mature leaves. The absorption of Zn by walnut leaves at high concentrations (7.5 to 15 mm Zn) was not significantly affected by the pH of the solution. In pistachio Zn absorption was greatest at pH 3.5 and declined as pH increased to 8.5. The uptake process was not affected by light or addition of metabolic inhibitors. Foliar leaf absorption was only slightly affected by changes in temperature with an average Q10 of 1.2 to 1.4. This study suggests that foliar Zn uptake is dominated by an ion exchange and/or diffusion process rather than an active one. This study also demonstrates the usefulness of stable isotope labelling in studies of foliar Zn absorption.

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