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1.
Clones of jarrah (Eucalyptus marginata), micropropagated from glasshouse-grown seedlings selected for resistance or susceptibility to Phytophthora cinnamomi, were planted in a former bauxite mine-site in the jarrah forest and inoculated with P. cinnamomi. Mortality after 13 years in resistant clones was 0–30%, while that of susceptible clones was 40–100%. Mean heights of resistant clones after 13 years were 7.8–13.6 m, while heights of surviving susceptible clones were 0.9–6.7 m. The resistance character of the seedling ortets was transmitted consistently to the clones. The field mortality of clones of some rare, apparently resistant seedlings selected from susceptible half-sib families was low after 1 year, but approached that of the susceptible clones after 2 years. The results show that Phytophthora-resistant jarrah ortets can be selected using stem-inoculation of glasshouse-grown seedlings; the resistance of the resulting clones has been validated in the field in an inoculation trial.  相似文献   

2.
The epidemic of bud rot disease affecting oil palm in Colombia is primarily caused by Phytophthora palmivora. The pathogen has a cosmopolitan presence that includes Southeast Asia, but to date, bud rot has not been reported in this region. This study provides an overview of the potential risk of Malaysian P. palmivora isolates cross‐infecting other host species, including cocoa, durian, rubber and Malaysian oil palm planting materials (Dura × Pisifera, D × P). On cocoa pods, the durian isolate PP7 caused dark brown necrotic lesions. Detached leaf bioassays showed that P. palmivora isolates PP3 and PP7 infected different hosts, except rubber foliage without wounding. Inoculation tests on cocoa, durian and rubber seedlings caused brown necrotic lesions when stems were wounded, with 10% mortality in cocoa and durian at 17 days post‐inoculation (dpi). However, no further infection was observed, and lesions closed within 14–28 dpi on the non‐wounded seedlings. Pathogenicity tests of oil palm seedlings inoculated with isolates PP3 and PP7 indicated that Malaysian P. palmivora isolates were not pathogenic to oil palms based on localized infection observed only through wounding. Overall, the work demonstrated that Malaysian P. palmivora isolates were able to cross‐infect multiple hosts but did not show severe infections on oil palms.  相似文献   

3.
Bud rot disease or “Pudricion del cogollo” (PC) of oil palm is a major constraint on production in Colombia and neighbouring countries such as Brazil, Costa Rica, Ecuador, Nicaragua, Panama, Peru and Surinam. To date, there are no documented reports of Phytophthora disease of oil palm in South‐East Asia. This research, therefore, was conducted to determine the pathogenic potential of Phytophthora palmivora and Phytophthora nicotianae on oil palm using both in vitro and nursery inoculation experiments. In vitro inoculation of both P. palmivora and P. nicotianae on immature oil palm leaflets caused discoloration within 2 days of inoculation and incubation at 25 ± 1.5°C, 100% RH. Similarly, in nursery trials, lesions formed on the buds (unopened leaflets) 3 days after inoculation with P. palmivora or P. nicotianae zoospore suspensions. No lesions developed on untreated leaflets in either in vitro or nursery inoculation experiments. Phytophthora spp. were re‐isolated from leaflet lesions and confirmed as the inoculated pathogens.  相似文献   

4.
In a few plant pathosystems, defeated major genes have been shown to contribute to partial resistance to disease. This hypothesis has never been tested before in a forest tree, but pathogenic variation associated with recent hybridization in poplar rust in the Pacific northwest provided an opportunity. An F2 progeny of 256 poplar clones in the field near Corvallis, Oregon, USA, has been monitored for rust severity and infection type since the advent of the new hybrid rust, Melampsora × columbiana, in the mid‐1990s. All 256 clones displayed a susceptible infection type in 1997 and again in 2000, and yet variation in uredinial density (i.e. partial resistance) was still observed. To determine which clones possessed a defeated resistance gene, a greenhouse inoculation was performed with an isolate of M. medusae, one of the parents of M. × columbiana. Clones that would have been resistant to M. medusae, prior to the advent of M. × columbiana, were thus identified. The inoculation resulted in a 1 : 1 segregation (χ2=0.772; p=0.38) for resistance, indicating the presence of a major gene. However, the F2 clones possessing the defeated resistance gene displayed the same level of partial resistance in the field in both 1997 and 2000 as their full siblings lacking the gene.  相似文献   

5.
In Brazil, the selection and planting of eucalyptus clones resistant to Ceratocystis fimbriata is the pre‐eminent control strategy for the wilt pathogen. However, little is known about host defence responses associated with resistance of eucalyptus to C. fimbriata infection. In this work, enzymatic activity, sugars, lignin, total phenols and phenolic compounds involved in the defence response of eucalyptus clones resistant (RC) and susceptible (SC) to the Ceratocystis wilt were evaluated. Changes were detected in the sugars produced by RC clones, with higher concentrations occurring compared with SC. A similar response occurred with lignin content at 28 days after inoculation (dai) in RC plants. SC plants had an increase in polyphenol oxidase and peroxidase activities at 7 dai. In contrast, RC plants demonstrated high activity of the same enzymes at 2 and 4 dai, decreasing afterwards. There was no difference in phenylalanine ammonia‐lyase activity between resistant and susceptible clones. Hydroxycinnamic acid concentration was higher in RC than in SC; however, there was no difference between RC and SC in flavonoid concentrations. RC had high concentrations catechin, chlorogenic acid and caffeic acid. Histochemical tests demonstrated the presence of phenolic compounds and lignin, at higher intensities, in xylem of RC plants. Inoculation with C. fimbriata induced defence responses in both resistant and susceptible eucalyptus clones, but both the intensity and speed of the responses were higher in RC. Alterations in the concentrations of sugars and lignin, as well as certain enzymes and phenolic compounds, could be used to predict the relative susceptibilities to Ceratocystis wilt of different phenotypes of eucalyptus clones.  相似文献   

6.
Ash dieback caused by the pathogenic fungus Hymenoscyphus fraxineus [previously known as H. pseudoalbidus (sexual stage) and Chalara fraxinea (asexual stage)] is a widespread problem in Europe. Here, we assess crown damage from natural infection and necrosis development following artificial controlled inoculations on full‐sib and half‐sib progeny from Danish Fraxinus excelsior clones with contrasting and well‐characterized levels of susceptibility to the disease. The inoculation assay was performed on a total of 123 offspring, and necrosis development monitored over two years. The offspring from low susceptible mother clones developed smaller necroses when compared to offspring from susceptible clones. Their crown damage due to natural infections was also significantly less. The correlation coefficient between average crown damages of mother clones and the average of their progeny was 0.85 (natural infections), while the correlation between crown damage of mother clones and the average necrosis development in their progeny after controlled inoculation was 0.73. The correlation between resistance of parent trees and crown damage/necrosis development on their offspring confirms the presence of heritable resistance and indicates that a bioassay based on controlled inoculations has the potential of becoming a fast and cost‐effective tool for estimation of dieback susceptibility in breeding programmes for resistance in ash trees.  相似文献   

7.
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   

8.
The oomycete Phytophthora cinnamomi is an aggressive plant pathogen, detrimental to many ecosystems including cork oak (Quercus suber) stands, and can inflict great losses in one of the greatest ‘hotspots’ for biodiversity in the world. Here, we applied Fourier transform‐infrared (FT‐IR) spectroscopy combined with chemometrics to disclose the metabolic patterns of cork oak roots and P. cinnamomi mycelium during the early hours of the interaction. As early as 2 h post‐inoculation (hpi), cork oak roots showed altered metabolic patterns with significant variations for regions associated with carbohydrate, glycoconjugate and lipid groups when compared to mock‐inoculated plants. These variations were further extended at 8 hpi. Surprisingly, at 16 hpi, the metabolic changes in inoculated and mock‐inoculated plants were similar, and at 24 hpi, the metabolic patterns of the regions mentioned above were inverted when compared to samples collected at 8 hpi. Principal component analysis of the FT‐IR spectra confirmed that the metabolic patterns of inoculated cork oak roots could be readily distinguished from those of mock‐inoculated plants at 2, 8 and 24 hpi, but not at 16 hpi. FT‐IR spectral analysis from mycelium of P. cinnamomi exposed to cork oak root exudates revealed contrasting variations for regions associated with protein groups at 16 and 24 h post‐exposure (hpe), whereas carbohydrate and glycoconjugate groups varied mainly at 24 hpe. Our results revealed early alterations in the metabolic patterns of the host plant when interacting with the biotrophic pathogen. In addition, the FT‐IR technique can be successfully applied to discriminate infected cork oak plants from mock‐inoculated plants, although these differences were dynamic with time. To a lesser extent, the metabolic patterns of P. cinnamomi were also altered when exposed to cork oak root exudates.  相似文献   

9.
A protocol has been developed for inoculation of rust disease in Dalbergia sissoo using urediniospores of Maravilia achroa. This is the first time that disease symptoms caused by M. achroa were artificially produced. The method has been successfully employed for screening 15 clones of D. sissoo against rust disease. Clone S‐167 was the most resistant remaining free from infection. Clones S‐57, S‐106 and S‐124 were also resistant. Clones S‐19, S‐24 and S‐89 were susceptible.  相似文献   

10.
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   

11.
Migration of the pine wood nematode (PWN), Bursaphelenchus xylophilus, in susceptible and resistant pines was investigated at the tissue level. PWN was inoculated onto the top cross‐cut surface of 20‐cm stem cuttings of susceptible Pinus thunbergii and resistant pines (P. strobus, P. rigida and P. thunbergii of a resistant family Namikata‐(t)‐73 (half‐sib)). PWNs were mainly distributed in cortical resin canals of susceptible P. thunbergii down to 15 cm from the inoculated surface by 6 h after inoculation (HAI) and all tissues (including cortical and xylem resin canals) down to the bottom at 192 HAI. In P. strobus, P. rigida and P. thunbergii family Namikata‐(t)‐73 (half‐sib), PWN was distributed in cortical resin canals down to 5 cm by 6 HAI and down to the base at 192 HAI. However, the distribution of PWN in xylem resin canals of the resistant pines was restricted near inoculated surfaces down to 5 cm, even at 192 HAI. These results demonstrated that migration of PWN in resistant pines was slowed in cortical resin canals and restricted in xylem axial resin canals, features which may be associated with the resistance.  相似文献   

12.
By 70 days after inoculation, resistant and tolerant clones of field-grown Cupressus sempervirens restricted penetration of the bark by Seiridium cardinale, forming ligno-suberized boundary zones which included four to six layers of cells with suberized cell walls. This response contrasted with that in susceptible clones, where only two to four layers of suberized cells were formed in discontinuous bands around inoculation sites. Detection of multiple layers of thin suberized boundary zones in susceptible clones indicated repeated penetration of the wound/infection-induced barrier by S. cardinale during a single growing season. The methods described will be valuable in the development of rapid, early and accurate screening programmes for durable resistance to Seiridium canker in Cupressus species.  相似文献   

13.
The activity of cell wall-degrading enzymes, produced in poplar cultivars infected Melampsora laricipopulina Kleb., was studied. The results show that PMG, PMTE, CX and β-glucosidase played roles during the infection. After inoculation, the activity of PMG in both susceptible and resistant cultivars had two peak values in 2 dpi and 5 dpi. The activities of PMTE and β-glucosidase had a peak value in 3 dpi, and CX in 2 dpi. Among these cell wall-degrading enzymes, the activities of PMG and PMTE were higher and the activities of CX and β-glucosidase were relatively lower. The activities of these cell wall-degrading enzymes were significantly higher in susceptible cultivars than those in resistant cultivars. All these demonstrated that these cell wall-degrading enzymes played certain roles in the infection of M. larici-populina. __________ Translated from Scientia Silvae Sinicae, 2008, 44(5): 79–83 [译自: 林业科学]  相似文献   

14.
The ascomycete Cryphonectria cubensis causes severe losses in Eucalyptus plantations in South Africa and selection programmes for disease tolerance are necessary. The aim of this study was to use two C. cubensis inoculation trials, planted at different locations to assess the disease susceptibility of the clones and the effect of the environment on disease development. These two trials consisted each of 21 Eucalyptus clones (E. grandis, E. grandis × camaldulensis and E. grandis × urophylla). All trees were inoculated with a single virulent strain of C. cubensis and lesion widths measured 6 and 12 months after inoculation. Clones differed significantly in their tolerance to C. cubensis. Further, disease severity differed depending on the geographical location of the trial. A significant clone × locality (genotype × environment) interaction was observed. Therefore, screening for disease resistance should take place only in areas where clones will be commercially grown.  相似文献   

15.
Artificial inoculation of rooted Eucalyptus grandis cuttings with Cryphonectria cubensis in the glasshouse showed that significant differences exist in the susceptibility of various Eucalyptus clones to the pathogen. A 61.3% difference in susceptibility was observed between the most resistant and susceptible group of clones. Results appeared, however, to have been influenced by genotype × environment interaction.  相似文献   

16.
Conventionally hybrid elm clones obtained within breeding programs for Dutch elm disease (DED) resistance were selected to meet requirements for use as ornamentals. However, it has been long and commonly observed that these clones may show hybrid vigour and enhanced growth. Nowadays DED resistant hybrid elm clones, which have been released to the market or are under evaluation for an upcoming release, are numerous enough to be considered for timber production or short rotation coppice (SRC). But experimental testing of the growth performances of these clones in different environments is still lacking. In this paper, growth and stability of performance of 24 DED resistant hybrid elm clones planted at three experimental sites with contrasting environmental conditions in Italy were studied. Height and diameter were measured yearly from 2001 to 2009, and the mean yearly increments after plant establishment were calculated. The study revealed a general good growth performance of the majority of the clones with mean height increments above 1 m/year, and an excellent growth performance of some genotypes. Analysis of variance showed significant effects of clone, site and clone × site interaction, for both height and diameter increments. Stability analysis of diameter and height increments was performed by using two parametric (CV% and W2) and two non-parametric (Hühn's Si(1) and Si(2)) indexes. According to all indexes, two clones showed superior and stable growth. These clones may be suitable for planting in a range of environments. In addition, several other clones had high growth in general or at a particular site. The results support our belief that these elm clones could be successfully used for timber and biomass production, and provide new knowledge for an informed choice of the most suitable genotypes.  相似文献   

17.
普通油茶无性系抗炭疽病评价   总被引：2，自引：0，他引：2       下载免费PDF全文
[目的]评价110个普通油茶无性系对炭疽病的抗病性,为油茶炭疽病抗性种质材料筛选和优良品种推广提供科学依据。[方法]采用田间调查方法和病情指数法,调查2014、2016年两年中110个普通油茶无性系的抗病性。[结果]在参试的110个普通油茶无性系中,未发现免疫(I)、高抗(HR)、高感(HS)无性系,抗病无性系10个,中抗无性系30个,中感无性系65个,感病无性系5个,其中9号、21号、27号、40号、45号、66号、150号、164号、177号、219号是10份抗病无性系。[结论]综合两年调查结果筛选出9号等10份抗病无性系,为深入研究普通油茶抗炭疽病机制和抗病育种提供了育种基础材料和参考依据。  相似文献   

18.
The foliage of seven different genera of conifers including 10 species and 17 different cultivars was tested for its susceptibility against two isolates of Phytophthora lateralis from two different lineages. Detached green shoot tips were floated in zoospore suspension and the lesion size was assessed after 7 days. xCupressocyparis leylandii, Juniperus media and Cedrus deodara were the most resistant hosts, whereas Chamaecyparis obtusa was most susceptible. Thuja plicata and Thuja occidentalis, Chamaecyparis pisifera and Chamaecyparis lawsoniana, Taxus baccata and Cupressus macrocarpa were of medium susceptibility. For comparison, a small subset of four hosts was also tested for stem susceptibility. The stems of whole potted plants were inoculated with the same two isolates as used for the leaf susceptibility tests. Chamaecyparis lawsoniana was highly susceptible, whereas the stems of xC. leylandii, T. baccata and T. plicata were not susceptible. Most conifers were similarly affected by both tested lineages of P. lateralis although the isolate of the Pacific Northwest lineage caused slightly longer lesions on C. lawsoniana in the stem inoculation tests.  相似文献   

19.
Eucalyptus polybractea (blue mallee) is the key species used in the commercial production of pharmaceutical-grade (>70% 1,8-cineole) eucalyptus oil in Australia. The establishment of plantations based on clones of selected, elite oil-producing plants has been recognized as the best means by which to increase oil and cineole yields. Blue mallee can be micropropagated using axillary bud proliferation of explants collected from the coppicing lignotubers of decapitated plants. To date, this has been successful for ortets from three different ontogenetic stages: 8-month-old ‘seedlings’, 4-year-old ‘saplings’ and ‘mature’, biannually harvested plants of indeterminate age. The issue of ontogenetic control of oil quality and quantity is an important consideration when selecting ortets for cloning and also when examining the success of a cloning programme. Our aim is to examine if clones derived from ortets of the three different ages reflect their respective ortets, in terms of oil quantity and quality (cineole proportion), and to appraise at what age the clones best reflect the ortets for these traits. Our results suggest that the age of ortets prior to explant collection does not influence micropropagation success or clonal consistency, and that clones generally exhibit the leaf oil traits of their respective ortets. Leaf oil quantity accumulation in ramets followed the ontogenetic trajectory of a relatively rapid increase to a maximum between 3 and 9 months, followed by a period of relative constancy for at least 12 months before beginning to gradually decrease after 21 months. Although oil quality of ramets reflected their corresponding ortets relatively well after 9 months, apparent ontogenetic constraints to cineole accumulation suggest that harvesting at a time between 9 and 21 months may better reflect the ortets for both traits. It appears likely that the proliferation of selected blue mallee genotypes using micropropagation will result in selection gains for key oil traits, thus potentially increasing cineole yields in future plantations.  相似文献   

20.
The pine wilt disease (PWD) is caused by Bursaphelenchus xylophilus and poses great environmental and economic challenges. Thus, the development of sustainable techniques for the control of this epidemic disease is of major importance. This work aimed at evaluating if the application of different molecular weight (MW) chitosans as a soil amendment could be used to control the PWD in maritime pine (Pinus pinaster, very susceptible to the disease) and stone pine (Pinus pinea, less susceptible). At the end of the experimental period (24 days after inoculation), P. pinaster and P. pinea untreated plants presented ca. 3825 ± 100 and 70 ± 47 nematodes, respectively. In P. pinaster, the high‐MW chitosan prompted the most drastic results, inducing a 21.9‐fold reduction in nematodes numbers, whereas in P. pinea, the most effective was the low MW chitosan, which reduced nematodes numbers up to 7‐fold, compared with untreated plants. P. pinea seems to be highly resistant to the disease, presenting nematode numbers up to 54.6‐fold lower than P. pinaster and less severe chlorophyll loss (ca. 2‐fold).  相似文献   

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