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Effectiveness of a detached‐leaf assay as a proxy for stem inoculations in backcrossed chestnut (Castanea) blight resistance breeding populations 
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下载免费PDF全文 A recently developed detached‐leaf blight resistance assay has generated interest because it could reduce the amount of time needed to evaluate backcrossed hybrid trees in the American chestnut blight resistance breeding programme. We evaluated the leaf inoculation technique on a sample of advanced progeny from the Indiana state chapter American Chestnut Foundation breeding programme, along with susceptible American chestnut (Castanea dentata), the recurrent parent, and resistant Chinese chestnut (Castanea mollissima), the donor parent for blight resistance. In experiments over 2 years using two pathogen isolates, we found no biologically meaningful relationship between leaf lesion size and the size (length and width) or severity (1–5 canker severity rating) of stem cankers on 5‐year‐old trees. Chinese chestnuts did develop significantly smaller leaf lesions than American or backcrossed chestnuts. We conclude that while the detached‐leaf assay may have utility in some chestnut breeding applications, it is not a suitable proxy for the established practice of stem inoculations. 相似文献
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Ten 5‐year‐old Betula pendula clones were studied for their rust resistance in the field. The trees were treated by inoculating 10 leaves on a shoot with Melampsoridium betulinum urediniospore suspension or spraying the control leaves with water. The birch clones differed significantly in their resistance to M. betulinum leaf rust fungus and the clones also varied in their responses to the local rust strain and the inoculated rust strains. However, natural rust infections and inoculation treatment were positively correlated. The older leaves had fewer infections than the younger ones on the tip of the shoot in the control trees, but in the inoculation treatment no significant correlation was found between the leaf ages and rust infection. The factors behind the different leaf susceptibilities are discussed. 相似文献
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Physiological and biochemical differences among Ulmus minor genotypes showing a gradient of resistance to Dutch elm disease 下载免费PDF全文
下载免费PDF全文 M. Li R. López M. Venturas J. A. Martín J. Domínguez G. G. Gordaliza L. Gil J. Rodríguez‐Calcerrada 《Forest Pathology》2016,46(3):215-228
Dutch elm disease (DED) spread across Europe and North America in the 20th century killing most natural elm populations. Today, breeding programmes aim at identifying, propagating and studying elm clones resistant to DED. Here, we have compared the physiology and biochemistry of six genotypes of Ulmus minor of variable DED resistance. Leaf gas exchange, water potential, stem hydraulic conductivity and biochemical status were studied in 5‐year‐old trees of AB‐AM2.4, M‐DV2.3, M‐DV2 × M‐CC1.5 and M‐DV1 and 6‐year‐old trees of VA‐AP38 and BU‐FL7 before and after inoculation with Ophiostoma novo‐ulmi. Leaf water potential and net photosynthesis rates declined, while the percentage loss of hydraulic conductivity (PLC) increased after the inoculation in susceptible trees. By the 21st day, leaf predawn and midday water potential, stomatal conductance to water vapour and net photosynthesis rates were lower, and PLC was higher in trees of susceptible (S) genotypes inoculated with the pathogen than in control trees inoculated with water, whereas no significant treatment effect was observed on these variables in the resistant (R) genotypes. Fourier transform infrared spectroscopy analyses revealed a different biochemical profile for branches of R and S clones. R clones showed higher absorption peaks that could be assigned to phenolic compounds, saturated hydrocarbons, cellulose and hemicellulose than S clones. The differences were more marked at the end of the experiment than at the beginning, suggesting that R and S clones responded differently to the inevitable wounding from inoculation and repeated sampling over the experimental course. We hypothesize that a weak activation of the defence system in response to experimental wounding can contribute to the susceptibility of some genotypes to O. novo‐ulmi. In turn, the decline in shoot hydraulic conductivity and leaf carbon uptake caused by the infection further exacerbates tree susceptibility to the fungus. 相似文献
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Alternaria leaf spot of Ailanthus excelsa is generally considered as minor disease in India. Recently, severe disease outbreaks were recorded in the nursery of the Forest Research Institute, Dehradun, progeny trial at Jhumpa, Haryana, and in a nearby farm field. Leaf symptoms included small circular, brown, necrotic spots with a chlorotic halo. With severe infections, leaf spots coalesced and resulted in leaf blight. A small‐spored Alternaria with concatenated conidia was isolated consistently from the leaf samples with spot symptoms. Sequence analyses of the internal transcribed spacer (ITS) region of ribosomal DNA (rDNA) and the translation elongation factor 1‐alpha (tef‐1α) gene region of two fungal isolates confirmed the species as A. alternata. In detached leaf assays, both isolates produced symptoms similar to those observed on the nursery/field‐grown plants. To validate the detached leaf assay result, pathogenicity was also demonstrated on whole plants in a glasshouse. Koch's postulates were fulfilled by re‐isolating A. alternata from the inoculated leaves. This work is the first to confirm that A. alternata is associated with leaf spot and blight disease of A. excelsa in India. 相似文献
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The multi‐use tree Canthium dicoccum (Rubiaceae) growing in shrub forests of Mysore, Mandya and Chamarajanagar (India) was severely affected by a leaf blight disease. The ascomycete Pestalotiopsis mangiferae was consistently isolated from symptomatic leaves and identified by micromorphology and ITS rDNA sequencing analysis. Pathogenicity test was performed and Koch's postulates were fulfilled. This is the first report of P. mangiferae causing leaf blight of C. dicoccum in India. 相似文献
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Marthin Tarigan Michael J. Wingfield Yosep M. A. N. Marpaung Alvaro Durán Nam Q. Pham 《Forest Pathology》2023,53(5):e12829
The Eucalyptus plantation industry in Indonesia has expanded rapidly during the last few decades. During routine nursery disease surveys, symptoms of a leaf and shoot blight disease were detected on Eucalyptus mother plants. Isolates were obtained from symptomatic tissues and identified using DNA sequence analyses. Phylogenetic analyses showed that the isolates were those of Quambalaria eucalypti. Pathogenicity tests were conducted with isolates of Q. eucalypti on clones of E. pellita and E. grandis × E. pellita hybrids. These resulted in symptoms similar to those observed on naturally infected plants. Eucalyptus genotypes tested showed variation in their susceptibility, highlighting the potential to select and breed for resistance and thus to manage future outbreaks of the disease. This is the first report of the pathogen in Indonesia as well as in Southeast Asia. 相似文献
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The presumed resistance of individual ash trees to ash dieback caused by invasive pathogen Hymenoscyphus fraxineus is an important issue for the maintenance of ash in European forests. All known studies regarding the resistance of ash trees to ash dieback were conducted in plantations and stands of F. excelsior; however, no such data exist for F. angustifolia. Crown damage assessments were performed over four consecutive years between 2009 and 2012 at a F. angustifolia clonal plantation in Hra??ica, Slovenia. Inoculation of H. fraxineus into the branches of the most and least damaged clones of F. angustifolia and leaf phenology assessments was performed to verify the presence of defence mechanisms that limit fungal growth or promote disease escape. Additionally, root collars of selected clones were inspected for fungal infections. The crown damage assessments showed considerable differences among F. angustifolia clones, indicating genetic variability in susceptibility to ash dieback. Crown dieback progressed significantly over the 4‐year time period; the mean crown damage of individual clones in 2012 varied between 16.7% and 83.8%. Significant differences among F. angustifolia clones were found in the inoculation trials and leaf phenology assessments. However, defence mechanisms such as early leaf flushing, early leaf shedding and the ability to inhibit pathogen growth in host tissues were not confirmed. High frequency of Armillaria spp. and H. fraxineus root collar infection demonstrated the need for whole tree inspection to determine causal agent of damages on individual ash trees. Armillaria spp. may be highly associated with ash decline epidemiology. 相似文献
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Ratnaboli Bose Shailesh Pandey Pooja Joshi Sabyasachi Banerjee Amit Pandey Maneesh S. Bhandari 《Forest Pathology》2021,51(1):e12658
Eucalyptus spp. and their hybrids are frequently cloned and mass planted across farmland tracts and commercial plantations in northern India. It is a viable feeder species to the paper and pulp industries in this region. In 2018 and 2019, during field surveys conducted in northern India, a serious leaf blight disease was frequently observed in E. tereticornis plantations. Isolation from the blighted leaf samples consistently yielded fungal isolates having Calonectria‐like morphology. Morphological features coupled with sequence analysis of partial β‐tubulin (TUB2) and partial translation elongation factor‐alpha (TEF1) gene regions of two fungal isolates confirmed the species as Ca. cerciana. In detached leaf assays and glasshouse inoculation experiments, both isolates produced symptoms similar to those observed on the naturally infected leaves. Koch's postulates were fulfilled by re‐isolating Ca. cerciana from the inoculated leaves. This work is the first to confirm that Ca. cerciana is associated with a serious leaf blight disease of Eucalyptus in northern India and is an important addition to the taxonomy of Calonectria fungi in India. 相似文献
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A 3‐year field study was carried out to determine the effect of wastewater irrigation and previous differences in mineral fertilization on the occurrence of willow leaf rust (Melampsora epitea). The experiment was conducted in two energy forest plantations: one designed for wastewater purification and the other as a mineral fertilization experiment. The severity of leaf rust on different clones and sites with different treatments was assessed by counting the number of uredinia per leaf unit area. Generally, plants irrigated with wastewater consistently had more leaf rust, irrespective of the study years or willow clones. Previous mineral fertilization had mixed effects on different clones 2 years after the last application. Three years after the last fertilizer application, however, no impact of the treatment on rust disease development was detected. In general, the rust levels differed from year to year probably due to climate. In this study, no correlation was detected between shoot age and rust severity, whereas climate and treatments strongly influenced leaf rust levels on some willow clones. 相似文献
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Thirty-six Hevea clones were inoculated with conidia of Microcyclus ulei, the causal agent of South American Leaf Blight in an air-conditioned chamber. Components of disease resistance such as latent period, infectious period, lesion size, percentage of damaged leaf area, number of lesions, spore production and stromatic generation period were studied during a single infection cycle. The clones were easily separated on the basis of these characters that were evaluated under controlled conditions. The main components that were highly correlated were the spore production, lesion size and number of lesions with the percentage of damaged leaf area. Others, such the stromatic generation period, were slightly correlated with all other components; latent period and infectious period was slightly correlated with the lesion size; and lesion size was slightly correlated with lesion density. For screening of varieties, damaged leaf area and spore production were the two components that should be considered the most important. Furthermore, the clones were tested for their capacity to produce scopoletin, a phytoalexin of Hevea, and to produce lignins in their infection sites. A strong correlation was observed between scopoletin accumulation and clone resistance. Moreover, strong lignin accumulation was often associated with a longer stromatic generation period. These two physiological reactions could interfere by limiting fungal development in several clones. However, neither scopoletin nor lignin accumulation could individually explain the behaviour of all clones. 相似文献
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在西双版纳采集优良无性系RRIM600、GT1和IAN873开放授粉种子(花粉来源复杂),繁殖成3个家系用作砧木试验,对其实生苗木逐株编号,在嫁接前测量6个性状指标并进行变异分析。结果表明,在家系内株高、地径、每蓬叶数、大叶柄长、小叶长、小叶宽等6个性状变异系数为11.19%~27.17%;IAN873种子苗木平均株高为222.14 cm,平均地径为22.48 mm,显著大于RRIM600和GT1种子苗木的株高和地径(P<0.01);3个家系苗木株高和地径基本符合正态分布,株高和地径与叶子4个性状相关密切。橡胶树的这3个家系间和家系内单株间都存在丰富的遗传变异。 相似文献
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Ganoderma lucidum is a serious root rot pathogen of trees and is known to cause large scale mortality in Dalbergia sissoo. Clones prepared from selected plus trees of D. sissoo have been established in a clonal seed orchard and a seed production area in northern India where 5‐year‐old plants of various clones were attacked by G. lucidum to varying degrees. Regular assessment was carried out for further 5 years to screen disease progress in the field and to identify clones of greater and lesser resistance. Data for height, clear bole and girth were collected to select trees with better growth form and disease resistance. Five highly resistant and five susceptible clones were categorized on the basis of total score for growth form characters and disease development. 相似文献
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本文比较测定了对叶枯病具有高度抗性的侧柏单株叶片中木质素和纤维素含量、苯丙氨酸解氨酶（ＰＡＬ）和超氧化物歧化酶（ＳＯＤ）、以及细胞含水量和肉质化程度。结果表明,抗病单株叶片细胞中木质素和纤维素的含量显著地高于普通的感病侧柏;抗病单株的ＰＡＬ活性和ＳＯＤ活性也明显高于感病株。并且发现ＰＡＬ活性和木质素含量之间具有高度相关性。抗病单株的细胞含水量和肉质化程度则显著地低于感病株。综上指标说明,抗病单株在生理生化和遗传上,明显地区别于普通感病株。 相似文献
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Talyta G. Zarpelon Andr C. da Silva Andr F. Santos Camila da S. Freitas Marcelo M. Coutinho Nairam F. de Barros Rodrigo G. de Freitas Acelino C. Alfenas 《Forest Pathology》2019,49(6)
Calonectria pteridis causes Calonectria leaf blight (CLB), and consequently severe defoliation in eucalypt plantations, which results in losses in wood volume. To reduce the negative impacts of this disease in eucalypt, this study aimed to assess the application of different doses and combinations of the macronutrients N, P and K on the percentage of symptomatic leaf area (SLA) and defoliation induced by the pathogen. Cuttings of a clone of Eucalyptus grandis were transplanted to pots containing soil that received different dose combinations of N, P and K, according to an incomplete factorial design. At 200 days after transplanting, leaf samples were analysed for N, P and K contents, and then, the plants were inoculated. Forty‐five days post‐inoculation, SLA and percentage of defoliation were quantified. Potassium doses above 75 mg/dm3 of soil significantly reduced SLA and defoliation. The influence of N and P on defoliation was dependent on K doses, but both reduced symptomatic leaf area. The best control of the disease, expressed by decreased defoliation and symptomatic leaf area, was achieved with leaf content of N, P and K of 9.8, 0.8 and 10.4 g per kg leaf, respectively, obtained with doses of 55, 82.5 and 143 mg/dm3of soil, respectively. Therefore, N, P and K nutrition can be a component of an integrated management programme for the control of CLB in eucalypts. 相似文献
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H. G. M. Ferraz G. A. Demuner L. M. S. Guimarães D. A. A. Arriel A. C. da Silva N. B. Junior R. G. Mafia A. C. Alfenas 《Forest Pathology》2016,46(3):240-247
The dieback and wilting caused by Erwinia psidii are emerging eucalypt diseases that have been observed since 2014 in the south and central‐south regions of Brazil. Field observations have shown variability in disease severity resistance among Eucalyptus spp. clones and species. It is hypothesized that this variability is due to genetic resistance. To confirm this hypothesis, inoculations in genetically distinct eucalypt plants are necessary. However, lack of an inoculation method and disease assessment makes difficult to select resistant genotypes for use in commercial plantations or genetic breeding programmes. Three inoculation methods were tested on eight clones of Eucalyptus spp. Among them, inoculum deposition with bacteria‐impregnated toothpick on the axillary buds was the simplest and most effective, capable to reproduce the disease symptoms observed under conditions of natural infection. We also developed a rating scale for disease assessment. Among eight clones tested, only Clone 1 (Eucalyptus saligna) and Clone 2 (Eucalyptus urophylla) were resistant. 相似文献
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Bacteria wilt (BW) of Casuarina equisetifolia L. Johnson, caused by Ralstonia solanacearum (E. F. Smith) Yabuuchi, is one of the most important diseases of C. equisetifolia L. Johnson, the main coastal protective forest tree in southeast China. The resistance of 33 C. equisetifolia L. Johnson clones to BW was determined by means of hydroponic and pot inoculation methods with the suspension of R solanacearum (E. F. Smith) Yabuuchi as inocula in the two‐step procedure. The results showed that clones FJ11 and FJ13 were highly resistant to BW with the lowest disease incidences of 10.8 and 15.8%, respectively, whereas clones FJ9 and GD15 were the most susceptible ones with the highest disease incidences of 100.0%. The analysis of AFLP markers was performed on clones FJ11, FJ13, FJ9 and GD15, and the results indicated that three DNA fragments E‐AAA/M‐CCG, E‐AAG/M‐CGC and E‐AGG/M‐CAA were found to be linked to the BW resistance. BLAST searches revealed that the first two fragments (GenBank accession numbers: KC111411 and KC135871) had no identities to any sequences, and the third one showed a high similarity to some sequences which code for heat shock protein. Taken together, the two resistant clones screened in our research were undoubtedly the valuable resistant resources of C. equisetifolia L. Johnson, and the three AFLP markers could be used in marker‐assisted selection of C. equisetifolia L. Johnson in the future. 相似文献
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R. Ghini R. E. de O. Mac Leod A. Torre Neto D. C. Cardoso W. Bettiol L. A. S. de Morais B. Vique 《Forest Pathology》2014,44(5):409-416
Evaluation of impacts of high CO2 atmospheric concentration is strategically important for the development of adaptation measures and sustainable crop management. The objective of this study was to evaluate the effects of increased atmospheric CO2 concentration on eucalypt rust (Puccinia psidii), C:N ratio, yield and chemical composition of essential oils and growth of eucalypt clonal plantlets. Two clones with different levels of rust resistance were studied: a Eucalyptus urophylla × E. camaldulensis hybrid (VM 01) and an E. urophylla (clone MN 463). The experiments were performed in open‐top chambers (OTCs) with CO2 mean concentrations (μmol mol?1) of 399 (unenclosed control), 412 (OTCs with ambient CO2 concentration) and 508 (OTCs with high CO2 concentration) and in closed chambers (CCs) with CO2 mean concentrations of 390, 405, 520 and 700. Increased atmospheric CO2 concentrations resulted in a decrease in rust pustules per leaf, uredinia per leaf area, spores per uredinia and area under the disease progress curve in VM 01 (hybrid) clonal plantlets. The disease did not occur in MN 463 clonal plantlets, which demonstrated that high CO2 concentrations did not change the level of rust resistance. Plant growth of the two clones was stimulated by up to 23% in height and 26% in stem diameter in OTCs and by 18% for both clones in CCs. An increased C:N ratio in leaves, stems and roots was observed only for the VM 01 clonal plantlets. Essential oils produced by VM 01 (2.8 g 100 g?1) and MN 463 (1.4 g 100 g?1), as well as the major essential oil compounds (80% 1.8‐cineole for VM 01; 50% 1.8‐cineole and 32% α‐pinene for MN 463), were not altered. In this study, increased concentrations of atmospheric CO2 favourably impacted eucalypt growth and reduced rust severity, while not influencing the production of essential oils. 相似文献
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Poplars are affected by a large number of foliar pathogens in nurseries and in the field, which result in biomass reductions. Management of these diseases is essential to minimise losses. During field surveys between 2008 and 12, an unrecognized leaf spot disease was observed on several commercial clones of P. deltoides (G‐48, Udai, WSL‐22 & WSL‐39). The pathogen was identified as Curvularia eragrostidis. Pathogenicity was proven on all host clones. This paper is the first report of the pathogen affecting poplars. 相似文献