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1.
Tika B. Adhikari Boovaraghan Balaji Jill Breeden Stephen B. Goodwin 《Physiological and Molecular Plant Pathology》2007,71(1-3):55-68
Large-scale cDNA-AFLP profiling identified numerous genes with increased expression during the resistance response of wheat to the Septoria tritici blotch fungus, Mycosphaerella graminicola. To test whether these genes were associated with resistance responses, primers were designed for the 14 that were most strongly up-regulated, and their levels of expression were measured at 12 time points from 0 to 27 days after inoculation (DAI) in two resistant and two susceptible cultivars of wheat by real-time quantitative polymerase chain reaction. None of these genes was expressed constitutively in the resistant wheat cultivars. Instead, infection of wheat by M. graminicola induced changes in expression of each gene in both resistant and susceptible cultivars over time. The four genes chitinase, phenylalanine ammonia lyase, pathogenesis-related protein PR-1, and peroxidase were induced from about 10- to 60-fold at early stages (3 h–1 DAI) during the incompatible interactions but were not expressed at later time points. Nine other genes (ATPase, brassinosteroid-6-oxidase, peptidylprolyl isomerase, peroxidase 2, 40S ribosomal protein, ADP-glucose pyrophosphorylase, putative protease inhibitor, methionine sulfoxide reductase, and an RNase S-like protein precursor) had bimodal patterns with both early (1–3 DAI) and late (12–24 DAI) peaks of expression in at least one of the resistant cultivars, but low if any induction in the two susceptible cultivars. The remaining gene (a serine carboxypeptidase) had a trimodal pattern of expression in the resistant cultivar Tadinia. These results indicate that the resistance response of wheat to M. graminicola is not completed during the first 24 h after contact with the pathogen, as thought previously, but instead can extend into the period from 18 to 24 DAI when fungal growth increases dramatically in compatible interactions. Many of these genes have a possible function in signal transduction or possibly as regulatory elements. Expression of the PR-1 gene at 12 h after inoculation was much higher in resistant compared to susceptible recombinant-inbred lines (RILs) segregating for the Stb4 and Stb8 genes for resistance. Therefore, analysis of gene expression could provide a faster method for separating resistant from susceptible lines in research programs. Significant differential expression patterns of the defense-related genes between the resistant and susceptible wheat cultivars and RILs after inoculation with M. graminicola suggest that these genes may play a major role in the resistance mechanisms of wheat. 相似文献
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A.T. Rodríguez R.M. Cárdenas M.G. Velázquez 《Pesticide biochemistry and physiology》2007,89(3):206-215
Seeds of rice (Oryza sativa L.) were treated with chitosan and hydrolyzed chitosan at 100, 500 and 1000 mg L−1. After 18 days of germination, spore suspension of Pyricularia grisea was applied. The enzyme activity of phenylalanine ammonia-lyase, β-1-3-glucanase, chitinase and chitosanase in leaves of rice seedlings was evaluated after 24, 72, 120 and 168 h of inoculation. Blast affected area (%) was evaluated 7 and 14 days after spraying spore suspension. Chitosan performance to elicit defense response induction was associated with the concentration and type of chitosan. The activity of most of the enzymes tested was induced in leaves of treated seeds with chitosan and hydrolyzed chitosan at 1000 and 500 mg L−1, respectively. The highest enzyme activities were observed with hydrolyzed chitosan after 72 h however, compared to chitosan, the activity was not maintained during the entire post-inoculation period. The highest control (0 = no lesions) of P. grisea in rice seedlings was observed at 1000 mg L−1 in both chitosan and hydrolyzed chitosan treated leaves. Symptoms of infection by P. grisea were evident after 14 days evaluation date, but according to the standard scale proposed by the International Rice Research Institute, these symptoms fell into the resistance category of blast diseases. 相似文献
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Regulation of defense-related enzymes associated with bacterial spot resistance in Tomato 总被引：1，自引：0，他引：1
Twenty tomato (Solanum lycopersicon) cultivars were screened for resistance against bacterial spot disease incited byXanthomonas axonopodis pv.vesicatoria under field conditions with and without pathogen infection. Screening was done by artificially inoculating aX. axonopodis pv.vesicatoria suspension to 4-week-old tomato seedlings and observing them for typical symptoms of the disease. Seedlings were categorized
into highly resistant, resistant, susceptible and highly susceptible cultivars on the basis of disease incidence. Tomato cultivars
were screened for defense-related enzymes, total phenols and lignin contents. The temporal patterns of all these enzymes were
estimated with a moderately susceptible tomato cultivar. Native PAGE analysis of both peroxidase (POX) and polyphenol oxidase
(PPO) was carried out for the time course of enzyme activities and also by selecting three different tomato cultivars, following
infection with the pathogen. Based on the inducible amounts of these enzymes upon pathogen infection, the tomato cultivars
were correlated with the disease incidence under field conditions. A significant (P≤0.05) correlation was observed between the degree of host resistance and the enzyme levels. In highly resistant tomato cultivars
the enzyme levels, total phenols and lignin contents were increased in comparison with highly susceptible tomato cultivars.
Isoform analysis of POX and PPO enzymes indicated a clear difference between resistant and susceptible tomato cultivars in
the number of isoforms and also in the intensity of each isoform in the presence of pathogen infection. The possible regulation
of defense-related enzymes in imparting host resistance is discussed.
http://www.phytoparasitica.org posting March 11, 2008. 相似文献
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Saïd Mouzeyar Felicity Vear Denis Tourvieille de Labrouhe 《European journal of plant pathology / European Foundation for Plant Pathology》1995,101(4):399-404
The mode of action of the fungicide metalaxyl againstPlasmopara halstedii, the causal agent of sunflower downy mildew, was studied following its application before, during and after artificial contamination of seedlings. The development of the fungus within the treated seedlings was examined microscopically and compared to that occuring in untreated genetically susceptible or resistant genotypes. Hypersensitive-like reactions and necrotic zones leading to the inhibition of fungus growth within the hypocotyl were observed for the three modes of application. This suggests that sunflower defence mechanisms activated by genetical resistance are also involved in the control of downy mildew by metalaxyl. 相似文献
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Plasmopara halstedii was isolated from diseased sunflowers collected from eight locations in the Czech Republic from 2007 to 2014. Races of the pathogen were determined based on 84 isolates collected during the study. In total, eight races of P. halstedii were detected using a set of nine sunflower differential lines. Races 700, 704, 705, 710, 714 and 715 were proven by soil drench inoculation, and two additional races (730 and 770) proposed by the previously applied leaf disc inoculation method. Race 700 was the most dominant in the Czech P. halstedii populations, with race 710 being the second most frequent. Races 704 and 714 were found over three seasons, while other races were recorded only in one growing season (race 730 in 2010, and the new races 705 and 715 in 2014). A comprehensive study was further conducted for isolates collected in 2013–14 using an extended differential set consisting of 15 sunflower lines. According to the latter methodology which marks races with five‐digit virulence codes, races 70060, 70471, 70571, 71060, 71461 and 71571 were recorded. The growing complexity of P. halstedii pathogenicity exhibited by the ability to infect higher numbers of differential genotypes and resulting in determination of the new pathogen races (virulence profiles) 70571, 71461 and 71571 is alarming. Although the limited number of isolates studied cannot characterize the entire pathogen diversity in the Czech Republic, the trend towards more diverse virulence in P. halstedii populations is clearly demonstrated by the new records of races 704, 705, 714 and 715, all capable of overcoming the resistance gene Pl6. 相似文献
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Cultivar‐dependent partial resistance and associated defence mechanisms in wheat against Zymoseptoria tritici 
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下载免费PDF全文 M. E. Ors B. Randoux S. Selim A. Siah G. Couleaud C. Maumené K. Sahmer P. Halama P. Reignault 《Plant pathology》2018,67(3):561-572
Septoria tritici blotch caused by the fungus Zymoseptoria tritici is one of the most devastating foliar diseases of wheat. Knowledge regarding mechanisms involved in resistance against this disease is required to breed durable resistances. This study compared the expression of defence and pathogenicity determinants in three cultivars in semicontrolled culture conditions. The most susceptible cultivar, Alixan, presented higher necrosis and pycnidia density levels than Altigo, the most resistant one. In Premio, a moderately resistant cultivar, necrosis developed as in Alixan, while pycnidia developed as in Altigo. In noninfectious conditions, genes coding for PR1 (pr1), glucanase (gluc) and allene oxide synthase (aos) were constitutively expressed at a higher level in both Altigo and Premio than in Alixan, while chitinase2 (chit2), phenylalanine ammonia‐lyase (pal), peroxidase (pox2) and oxalate oxidase (oxo) were expressed at a higher level in Premio only. Except for aos, all genes were induced in Alixan during the first steps of the symptomless infection phase. Only pox2, oxo, gluc and pal genes in Altigo and pal, chs and lox genes in Premio were up‐regulated at some time points. Basal cultivar‐dependent resistance against Z. tritici could therefore be explained by various gene expression patterns rather than high expression levels of given genes. During the necrotrophic phase, Z. tritici cell wall‐degrading enzyme activity levels were lower in Altigo and Premio than in Alixan, and were associated more with pycnidia than with necrosis. Similar tissue colonization occurred in the three cultivars, suggesting an inhibition of the switch to the necrotrophic lifestyle in Altigo. 相似文献
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Owen Wally Jayaraman Jayaraj Zamir Punja 《European journal of plant pathology / European Foundation for Plant Pathology》2009,123(3):331-342
Genes encoding an acidic wheat class IV chitinase (383), an acidic wheat β 1,3-glucanase (638) and a rice cationic peroxidase
(POC1) were introduced into ‘Nantes Coreless’ carrot (Daucus carota) by Agrobacterium-mediated transformation. The genes were introduced singly or in various combinations followed by selection imposed by the
herbicide phosphinothricin. Regenerated plantlets were screened for presence and expression of the three transgenes using
PCR, Southern and Northern hybridisations. Eighteen transgenic lines expressing a single transgene and 2 lines each co-expressing
638/383 and 383/POC1 were assessed for resistance to the necrotrophic fungal pathogens Botrytis cinerea and Sclerotinia sclerotiorum. Percentage leaf area diseased was measured 4 and 7 days after inoculation (dai) and compared to non-transformed control
plants. Six lines expressing β-1,3-glucanase 638 alone had no enhanced resistance to B. cinerea at 4 dai and only slight resistance to S. sclerotiorum; there was no effect at 7 dai. Two out of the six lines expressing 383 alone had enhanced tolerance to both pathogens with
a 20–50% reduction in disease development at 7 dai. Two lines co-expressing 638/383 had slight reductions in disease by (10–20%)
similar to that of the lines expressing chitinase 383 alone. Highest levels of disease resistance were seen in transgenic
lines expressing POC1, alone or in combination with chitinase 383. Disease symptoms were slower to develop and symptoms were
reduced by up to 90% for B. cinerea and 70% for S. sclerotiorum. The 383/POC1 co-expressing plants developed disease at levels similar to that of POC1 alone. Petioles of plants over-expressing
POC1 had higher levels of lignin accumulation constitutively compared to control plants, which was greatly enhanced following
inoculation with S. sclerotiorum. These results indicate that peroxidase over-expression can lead to significant disease reduction against necrotrophic pathogens
in transgenic carrot plants. 相似文献
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Tomato early blight occurs worldwide and it is prevalent wherever tomatoes are grown. Alternaria solani Sorauer, the causal agent, has been recognized as a serious foliar pathogen of tomato and there are very few cultivars which
possess resistance against early blight. Alternaric acid is the major toxin of A. solani. In this study, alternaric acid and fungal culture filtrate were used as an elicitor in NDT-96 (tolerant) and GP-5 (susceptible)
tomato varieties in order to study and compare their abilities to induce defense-related enzymes, viz., catalase, peroxidase, β-1,3 glucanase, phenylalanine-ammonia-lyase (PAL), chitinase and polyphenol-oxidase (PPO) along with
total phenols, and total soluble proteins. NDT-96 showed a rapid induction of all these pathogenesis-related enzymes except
catalase along with total phenols as compared to GP-5 with both the treatments. Differential expression of total soluble proteins
revealed higher protein content in NDT-96 as compared with GP-5. A 49.48 kDa protein was observed to be absent in GP-5. In
addition, 25 microsatellite markers (SSR) were screened for polymorphisms among the above mentioned two tomato varieties.
Of these, SSR 286 revealed a significant polymorphic band of 108 bp in NDT-96. 相似文献
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BACKGROUND: The present study investigated the effect of chitosan seed priming on the induction of disease resistance in pearl millet against downy mildew disease caused by Sclerospora graminicola (Sacc.) Schroet. RESULTS: Pearl millet seeds were primed with chitosan at different concentrations: 0.5, 1.5, 2.5 and 3 g kg?1 seed. Of the different concentrations, 2.5 g kg?1 was found to be optimum, with enhanced seed germination of 99% and seedling vigour of 1782, whereas the untreated control recorded values of 87% and 1465 respectively. At optimum concentration, chitosan did not inhibit sporulation and release of zoospores from sporangia. Furthermore, pearl millet seedlings raised after seed treatment with chitosan showed an increased level of the defence‐related enzymes chitosanase and peroxidase as compared with the untreated pearl millet seedlings on downy mildew pathogen inoculation. The effect of chitosan in reducing downy mildew incidence was evaluated in both greenhouse and field conditions, in which respectively 79.08 and 75.8% disease protection was obtained. CONCLUSION: Chitosan was effective in protecting pearl millet plants against downy mildew under both greenhouse and field conditions by inducing resistance against the pathogen. Thus, chitosan formulation can be recommended for seed treatment in the management of downy mildew disease. Copyright © 2008 Society of Chemical Industry 相似文献
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Ferenc Viranyi Otmar Spring 《European journal of plant pathology / European Foundation for Plant Pathology》2011,129(2):207-220
This review summarises the progress in research on sunflower downy mildew as reported in publications of the past 10 to 15 years,
the period since the last comprehensive review on Plasmopara halstedii. Particular attention is paid to subjects that showed much progress and may be of particular interest to sunflower pathologists,
mycologists or molecular biologists. Accordingly, single sections are devoted to the problems of taxonomic and phylogenetic
aspects, host specificity, the host—pathogen interaction including resistance phenomena, as well as epidemiology and disease
management. Reflecting the progress achieved in some fields and illuminating the deficits in others should stimulate the reader's
interest in this very significant pathosystem. 相似文献
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Yoshikatsu Genda Kyoko Sato Osamu Nunomura Tetsuo Hirabayashi Shinya Tsuda 《Journal of General Plant Pathology》2011,77(3):201-208
The location of Pepper mild mottle virus (PMMoV) within seeds as they developed on inoculated seedlings of pepper (Capsicum annuum) was followed over time by detecting the viral coat protein using immunofluorescence microscopy. Seedlings were inoculated
with PMMoV when the flower buds on the first and second branching nodes were in bloom. Fluorescence indicating the presence
of PMMoV was first observed around immature seeds and placentas in the ovaries on the fourth branching node at 20 days post-anthesis
(20 DPA), which corresponded to 39 days post-inoculation (39 DPI). The area with fluorescence gradually expanded from the
placenta into the integument and the parenchyma, and finally reached the tip of the immature seeds by 34 DPA (53 DPI). The
embryo or endosperm beyond the endothelium never fluoresced during the experiment [i.e., ending at 81 DPA (102 DPI)]. For
visualizing viral routes of invasion from seeds into new seedlings, PMMoV-infected C. annuum seeds that were heterozygous for the L
3
tobamovirus-resistance gene were sown in soil at 30°C. After ~2 weeks, the cotyledon developed virally induced necrosis.
These findings shed light on the infection cycle of PMMoV through vertical transmission in C. annuum. 相似文献
17.
Eleonora Barilli Elena Prats Diego Rubiales 《European journal of plant pathology / European Foundation for Plant Pathology》2010,128(4):483-493
Benzothiadiazole (BTH) and DL-β-aminobutyric acid (BABA) induced systemic resistance was investigated in susceptible and resistant
pea genotypes against Uromyces pisi. Resistance was characterized by reduced infection frequency mainly due to decreases in appressorium formation, stomatal
penetration, growth of infection hyphae and haustorium formation. Changes in β-1,3-glucanase, chitinase, phenylalanine ammonia-lyase
and peroxidase activities and in total phenolics content, demonstrate that U. pisi resistance is induced by BTH and BABA treatments at early and late stages of the fungal infection process, but that the chemicals
operate via different mechanisms. In fact, our study showed that BTH treatment primed the activity of pathogenesis related-proteins
such as β-1,3-glucanase, chitinase and peroxidase in both susceptible and resistant genotypes. On the other hand, BABA treatment
did not increase the enzymatic activities in the studied genotypes, but significantly increased their total phenolic contents. 相似文献
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Tobacco becomes naturally resistant to blue mould caused by Peronospora tabacina as it ages. This age-related resistance is correlated to the time of normal floral development and the senescence of lower leaves: however, it is dependent on neither. β-1,3-Glucanase, chitinase and peroxidase activities increase in tobacco with age. These increases correlate with the development of age-related resistance to blue mould and were independent of floral development. Additionally. β-1,3-glucanase, chitinase, and peroxidase activities were higher in leaf tissue from the main stalk resistant to blue mould) as compared to leaf tissue from suckering stems (susceptible to blue mould) on the same plant. Isozyme patterns of β-1,3-glucanase and chitinase in all resistant tissues are typical of those of tissues systemically protected by either stem injection with Peronospora tabacina or foliar inoculation with TMV. 相似文献
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Pamela Paparu Thomas Dubois Danny Coyne Altus Viljoen 《Physiological and Molecular Plant Pathology》2007,71(4-6):149-157