查看更多>>摘要：Abstract Thuja occidentalis L. is an evergreen coniferous species of high medicinal value with fan‐like branches and scaly leaves. Leaf yellowing symptoms were recorded on T. occidentalis plants in 2019 at Mukteshwar, Uttarakhand, India. Using the universal 16S rRNA and secA gene phytoplasma‐specific primers, the expected amplicons of ~1.25?kb and 480?bp were consistently obtained in ten symptomatic thuja leaf samples. Virtual RFLP profiles showed that the thuja phytoplasma strains were associated with Ca. Phytoplasma australasia (16SrII‐D subgroup)‐related strain by matching the restriction patterns of the 16S rRNA gene. This is the first time a phytoplasma from the 16SrII‐D subgroup has been recorded with thuja yellows disease in the world.
查看更多>>摘要：Abstract A severe outbreak of foot rot and head rot disease of cabbage was observed during September 2017 to November 2019 in major cabbage growing regions of southern Karnataka state of India. The disease incidence ranged between 3% and 28%. The initial symptoms were observed as tan, water‐soaked lesions at the point of infection and development of mycelia, followed by quick wilting of the whole plant. Subsequently, numerous sclerotia were produced. The pathogen isolated on PDA medium produced white fluffy aerial mycelia and numerous reddish‐brown sclerotia after 7?10?days. A total of 18 fungal isolates were used for mycelial compatibility analysis. Isolate SrBoC28 was used to test for pathogenicity on cabbage, marigold, chilli and brinjal plants. Typical disease symptoms on leaves, stem and roots were evident 5, 8 and 10?days’ post‐inoculation respectively. The isolate was pathogenic on all tested hosts, and the identity was confirmed by re‐isolation and morpho‐cultural and molecular studies. The latter were based on amplification of ITS‐rDNA and phylogenetic analysis which showed 100% sequence similarity with reference sequences. The identity was confirmed as S. rolfsii. This is a well‐known pathogen and causes disease on various economically important crop plants. To date, there are no reports on the association between S. rolfsii and foot and head rot disease of cabbage in India and elsewhere. Thus, to the best of our knowledge, this is the first report of foot rot and head rot of cabbage caused by S.?rolfsii in India.
查看更多>>摘要：Abstract Zhi mu (Anemarrhena asphodeloides Bunge.) is an important medicinal plant in China, and its growth is greatly threatened by the fungal disease anthracnose, which can be caused by a number of species of Colletotrichum. Studying the phytopathogen and its sensitivities to fungicides will help to control anthracnose on zhi mu. Ten isolates of Colletotrichum were collected from zhi mu in Hebei, Anhui and Shanxi Provinces in China for this study. The isolates were identified as C.?gloeosporioides, C.?liriopes and C.?spaethianum based on multi‐locus phylogenetic analyses, including ACT, CHS‐1, GADPH, HIS3 and ITS, micromorphological characteristics and the characteristics of colonies. Koch's postulates were confirmed by inoculating the leaves of zhi mu in vitro. The levels of virulence of 10 isolates varied significantly. Isolate YC‐1 was the most virulent, while BZ‐2 was the least virulent. The sensitivity of isolates YC‐1, BY‐1 and BY‐2 (C.?spaethianum, C.?gloeosporioides and C.?liriopes respectively) to fungicides were examined. The EC50?values of BY‐1, BY‐2, and YC‐1 to tebuconazole, difenoconazole, prochloraz, fludioxonil, pyraclostrobin, carbendazim and azoxystrobin confirm that all of the isolates were markedly sensitive to the seven fungicides tested, strongly suggesting that these fungicides could be used to control anthracnose on zhi mu in the field.
Anowara AkterSheikh Arafat Islam NihadMd. Jamil HasanLutful Hassan...
9页
查看更多>>摘要：Abstract Bacterial blight (BB) disease, caused by Xanthomonas oryzae pv. oryzae (Xoo), is one of the major bottlenecks of rice (Oryza sativa) production. The present study was undertaken to identify BB‐resistant parental lines of hybrid rice based on pathogenicity tests and molecular screening. Three virulent races of Xoo, i.e. BXo93, BXo822 and BXo887 were used to evaluate the 66?maintainers and 200 elite restorer lines against BB. Based on the pathogenicity test, none of the maintainer lines was found resistant, whereas 16 restorers were resistant against the three races and 15 restorers were resistant to a single race (Bxo93). These 31 restorer lines were selected to detect the presence of major bacterial blight resistance genes, i.e. Xa4, xa5, Xa7, xa13, Xa21 and Xa23 using molecular markers. Thirteen restorer lines carried the Xa4?gene but were not resistant to all three races of BB. Fourteen restorers and one restorer had two (Xa4?+?xa5; Xa4?+?Xa7; Xa4?+?Xa21 and Xa7?+?Xa21) and three (Xa4?+?xa5?+?Xa7) BB resistance genes, respectively. Genotypes having Xa21, Xa7?+?Xa21 or Xa4?+?Xa21?had reduced lesion lengths that ranged from 1.4?cm (against BXo93)–3.0?cm (against BXo887), 1.6?cm (against BXo93)–2.0?cm (against BXo822 and BXo887) and 2.5?cm (against BXo887)–3?cm (against BXo822), respectively, and were found to be the most effective resistance genes against bacterial blight. The restorer lines having the Xa21, Xa7?+?Xa21 or Xa4?+?Xa21 could be used as parental lines for the development of bacterial blight‐resistant hybrid varieties.
查看更多>>摘要：Abstract Iris lactea is a wide ground cover plant of importance throughout courtyards, trees and roads. From May to September in 2020 and 2021, I.?lactea planted in Beijing showed white to yellow spots with black conidiomata and could lead blight expanded down from the tip of leaves. In this study, ninety‐six diseased leaves were collected from nineteen regions in Beijing, and a total of fifty‐nine Colletotrichum isolates were obtained from the leaf spots. All isolates were identified as Colletotrichum truncatum by polyphasic analyses, combing morphology and phylogeny of combined the internal transcribed spacer of rDNA region (ITS), actin (act), chalcone synthetase (chs), the genes of glyceraldehyde‐3‐phosphate dehydrogenase (gapdh) and β‐tubulin (tub2). Koch's postulates were confirmed by a pathogenicity test using conidial suspensions (1?×?106 conidia/ml) on fresh leaves of the host, re‐isolation and identification. Until now, this is the first confirmed report of a new anthracnose disease of I. lactea caused by C. truncatum in China.
查看更多>>摘要：Abstract Xanthomonas campestris pv. campestris (Xcc), the pathogen of black rot of crucifers, could be induced into the viable but nonculturable (VBNC) state under stress, such as being induced by low concentration of Cu2+ and acid condition induction. The main objective of current study was to select the optimal reference genes for data normalization by qPCR in the VBNC state of Xcc. In this study, Xcc was induced into VBNC state by Cu2+ with an initial concentration of OD600 = 0.18 and OD600 = 0.45, and all viable bacterial cells lost the culturability and entered into the VBNC state at 24?h and 48?h respectively. The concentration of VBNC cells was 3.3 × 107 cells/ml and 1.5 × 107 cells/ml respectively. Eight candidate reference genes (gyrB, pbpA, gapA, rpoB, tufA, 16S rRNA, ugpC and recA) were selected to assess the expression stability in the VBNC state of Xcc by four algorithms (geNorm, NormFinder, delta‐Ct and BestKeeper), while RefFinder was used to integrate the output from the four algorithms in fine. According to the algorithm analysis and validation of clpX expression analysis, the most suitable reference gene this study identified was the combination of ugpC and pbpA, and the least suitable gene was 16S rRNA in the Xcc VBNC state. In this study, we identified the most stable internal controls under Cu2+‐inducing conditions for calibration qRT‐PCR analyses of Xanthomonas campestris pv. campestris and will be helpful to explore the stress resistance mechanism in this bacterium.
Jéssica Maria Israel JesusAna Beatriz Lemes RodriguesKássia Lorrany Marques PaulaMarcos Gomes Cunha...
6页
查看更多>>摘要：Abstract Among the main ornamental plants grown in Brazil, Adenium obesum stands out for its appearance, drought resistance and beautiful flowers. However, diseases can be a limiting factor because they affect crop quality and yield. The aim of this study was to report the first occurrence of Pestalotiopsis microspora as the causal agent of leaf spots on desert rose. A.?obesum leaves with necrotic spots on the edges and/or tips were collected for indirect isolation of the pathogen. Three morphologically similar fungal isolates were obtained. In pathogenicity testing, healthy leaves were inoculated with mycelial disks and controls with disks containing potato dextrose agar (PDA) medium. Symptom development was assessed on a daily basis, followed by reisolation. The DNA of pure cultures was extracted and submitted to PCR using the primers ITS1 and ITS4. The PCR product was sequenced. The inoculated leaves initially developed symptoms of chlorosis that progressed to necrosis. The fungal colonies exhibited white mycelia with radial, cottony growth and the formation of dark masses of conidia and hyaline, branched septate hyphae. The euseptate conidia had two hyaline cells (apical and basal) and three dark‐coloured fusiform median cells. The morphological characteristics of the isolates were similar to those described for the genus Pestalotiopsis. When compared to sequences deposited in GenBank, the sequences of the ITS gene showed 100% identity with the Pestalotiopsis microspora species. These results extend the range of known hosts of this pathogen, since this is the first report of P.?microspora attack in Adenium obesum.
查看更多>>摘要：Abstract Amongst the fungi that cause damage to common bean (Phaseolus vulgaris) and are disseminated by seeds, Colletotrichum lindemuthianum stands out. This fungus causes anthracnose in common bean plants. The use of natural compounds, for example essential oils (EO), is a viable and safer option than chemicals to manage this disease. According to the results of the in vitro assay, we observed complete inhibition of the growth of C.?lindemuthianum with the use of Cinnamomum cassia EO and its major component (E)‐cinnamaldehyde, presenting MIC of 125?μg/ml, whilst the commercial fungicide presented MIC of 30.6?μg/ml. In addition in vivo assay, where seeds naturally infected with C.?lindemuthianum were treated with the EO and the substance in a solution with commercial soybean oil, we observed reducing the incidence of anthracnose over the days evaluated, as well as for the commercial fungicide used (thiophanate‐methyl). In addition, the treatments did not affect germination and initial seed vigour. This is the first study to demonstrate the efficacy of Ci.?cassia essential oil and (E)‐cinnamaldehyde on the control of C.?lindemuthianum through the treatment of common bean seeds.
查看更多>>摘要：Abstract The genus Orthotospovirus contains a variety of viruses that infect more than 1000 plant species of 82 families. Nine medicinal plant species were found to exhibit symptoms that are typical of plant viral infections. Foliar samples of diseased plants were taken, and double‐antibody sandwich ELISA (DAS‐ELISA) and reverse transcription polymerase chain reaction (RT‐PCR) analyses were used to detect the viruses in the diseased plants. The results revealed that Capsicum chlorosis orthotospovirus (CaCV) was present in Salvia miltiorrhiza and Valeriana jatamansi. Impatiens necrotic spot orthotospovirus (INSV) was identified in Plantago asiatica, Scrophularia ningpoensis and Iris tectorum. Tomato spotted wilt orthotospovirus (TSWV) was detected in Perilla frutescens, while Tomato zonate spot orthotospovirus (TZSV) was found in Codonopsis spp., Marsdenia tenacissima and Dipsacus asper. Phylogenetic tree analysis also reflected the high consistency of sequences. To our knowledge, this is the first report of CaCV in Salvia miltiorrhiza and Valeriana jatamansi and INSV in Plantago asiatica, Scrophularia ningpoensis and Iris tectorum. This is also the first report of TSWV infecting Perilla frutescens and TZSV infecting Codonopsis spp., Marsdenia?tenacissima and Dipsacus asper.
Ana Carolina Lyra BrumatLouise Larissa May De MioDauri José TessmannCelso Garcia Auer...
9页
查看更多>>摘要：Abstract Persimmon fruit (Diospyros kaki L.) from commercial orchards located in southern Brazil, in Curitiba, Paraná, showed dark firm rot. The incidence in the field was about 2% in an evaluation in the 2016 growing season, and from these infected fruit, three Phytophthora sp. isolates were obtained. Therefore, this study aimed to identify the causal agent of the disease through morphophysiological and molecular analysis of the isolates. Initially, the pathogenicity test was performed on persimmon fruit to fulfil Koch's postulates. Mycelial growth at eight temperatures ranging from 8°C to 35°C was evaluated for taxonomic purposes. Next, the morphological characteristics of sporangia, chlamydospores and oospores were evaluated. For molecular characterization, sequencing of the ITS‐rDNA region and portions of the COXI and TEF1α genes and phylogenetic analysis were performed. All isolates were pathogenic, causing symptoms of firm and dark rot similar to those observed in the orchards. Mycelial growth was not observed at 35°C. There was an abundant production of ellipsoid, papillate, deciduous sporangia with long pedicels and the formation of globose chlamydospores. The isolates were heterothallic, all belonging to group A1, in which the production of plerotic oospores with amphigenous antheridia was verified. The morphophysiological and molecular characterization allowed the identification of the isolates as Phytophthora tropicalis. To our knowledge, this is the first report of persimmon fruit rot caused by P.?tropicalis.
NSTL
Wiley