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1.
Daylily rust fungus, Puccinia hemerocallidis, was proven to host-alternate between a wild daylily, Hemerocallis fulva var. longituba, and a patrinia, Patrinia villosa. No proof was obtained for the early belief that the fungus is pathogenic to plantainlilies, Hosta species, in addition to daylilies, Hemerocallis species. The fungus seems to alternate regularly between daylilies and patrinias in Japan because most daylily species are deciduous, and a vegetatively reproducing stage of the pathogen does not seem capable of successfully overwintering free of the living host tissue. 相似文献
2.
Hadis Shahbazi Heshmatolah Aminian Navazollah Sahebani Dennis A. Halterman 《Phytoparasitica》2011,39(5):455-460
Early blight of potato, caused by Alternaria solani, is a ubiquitous disease in many countries around the world. Our previous screening of several Iranian potato cultivars found that variation in resistance exists between two cultivars: ‘Diamond’ and ‘Granula’. Cultivar Diamond is more resistant to multiple isolates of A. solani when compared to cv. Granula. Furthermore, we have found that different pathogen isolates have varying degrees of infection. We monitored the activities of two pathogen-related (PR) glucanase proteins in Diamond and Granula in response to two isolates of A. solani with different degrees of virulence. ß-1,3-glucanase and ß-1,4-glucanase activities were recorded in healthy and diseased leaves of potatoes up to 10 days after inoculation. Their activities were found to be higher in diseased leaves when compared to those of uninfected leaves. Our data suggest that significantly reduced activities of theses enzymes in potato could be related to a lower degree of resistance or an increased ability of a more aggressive isolate to suppress PR protein expression. 相似文献
3.
H. D. Coletta-Filho E. F. Carlos K. C. S. Alves M. A. R. Pereira R. L. Boscariol-Camargo A. A. de Souza M. A. Machado 《European journal of plant pathology / European Foundation for Plant Pathology》2010,126(1):53-60
The bacterium Candidatus Liberibacter asiaticus (CLas) is associated with huanglongbing (HLB) in citrus in many countries. Despite the fact that many
characteristics of the disease are known, the rate of multiplication of the bacterium within an infected tree is still poorly
understood. To study this feature, we used the quantitative Real-Time polymerase chain reaction (Q-PCR) assay to follow and
to quantify the multiplication of CLas in grafted infected young sweet orange plants. The rate of infection by grafting reached
100% at 120 days post-inoculation (dpi) showing that grafting could easily transmit CLas. A well-adjusted linear regression
equation describing the bacterial growth in planta was obtained independently with measurements taken using repeated sampling in the same plant or different plants through
the analysed period. The bacterial population, measured as copy number (CN) of the 16S rDNA target gene g−1 of tissue, increased 10,000 times from 103 at 30 dpi to approximately 108 CN at 240 dpi indicating that CLas multiplication was fastest in young citrus plants. We observed a direct relationship between
the concentration of pathogen and the expression of symptoms. Yellowed leaves or shoots, are commonly the first observed symptom
of HLB, and were present in trees with a low amount of bacteria (105 CN g−1). Blotchy mottle symptoms were observed in trees with 107 CN g−1 of bacteria after 180 dpi. Buds taken from infected, but non-symptomatic branches were grafted on Rangpur lime and resulted
in transmission rates ranging from 10 to 60%. 相似文献
4.
Nozomu Iwabuchi Ai Endo Norikazu Kameyama Masaya Satoh Akio Miyazaki Hiroaki Koinuma Yugo Kitazawa Kensaku Maejima Yasuyuki Yamaji Kenro Oshima Shigetou Namba 《Journal of General Plant Pathology》2018,84(2):160-164
“Elaeocarpus yellows” (ELY) is a widely reported phytoplasma disease of Elaeocarpus zollingeri trees in Japan. The phytoplasma associated with ELY (ELY phytoplasma) had not been identified at the species level because its 16S rRNA sequence had yet to be reported. Here, we report the results of a sequence analysis based on 16S rRNA and secA gene sequences, which showed that the ELY phytoplasma is related to ‘Candidatus Phytoplasma malaysianum’. To our knowledge, this is the first report showing the occurrence of ‘Ca. P. malaysianum’ outside Malaysia and the infection of E. zollingeri by the phytoplasma. 相似文献
5.
C.A. Antolínez A. Fereres A. Moreno 《European journal of plant pathology / European Foundation for Plant Pathology》2017,147(3):627-637
‘Candidatus Liberibacter solanacearum (Lso)’ is a pathogen of Solanaceae but also causes serious physiological disorders in carrots and celery (Apiaceae). In carrots, this pathogen is transmitted by the psyllids Bactericera trigonica and Trioza apicalis. How vector sex influences Lso transmission has not been yet elucidated. Here we report the probing behaviours of male and female B. trigonica and their impact on Lso titre transmitted, percentage of transmission, and symptoms produced on carrots when Lso is transmitted by males or females of B. trigonica. Vector sex affected the inoculation of Lso; our results suggest that females might inoculate higher Lso titres than males. However, the percentage of transmission was not affected by vector sex at a density of one or eight psyllids per plant. The number of yellow leaves and root weight were not different when Lso was transmitted by males or females at either of the psyllid densities tested, except for groups of females whose Lso transmission resulted in a higher number of yellow leaves than did Lso transmitted by groups of males. Electrical penetration graphs (EPG) showed that the proportion of individuals who reached phloem tissues was similar for males and females. However, EPGs also showed that females probed more times, ingested longer from phloem sieve elements and reached phloem tissues more frequently than did males during an 8-h inoculation access period (IAP). Our study shows that differences in probing behaviours between males and females of B. trigonica could modulate how Lso is inoculated by psyllids. These results highlight the importance of taking sex into consideration in psyllid studies of probing behaviour and bacterial transmission. 相似文献
6.
Citrus scab, caused by Elsinoë fawcettii (anamorph Sphaceloma fawcettii), is a common foliar fungal disease affecting many citrus cultivars, including grapefruit. No commercial grapefruit cultivar is resistant to scab, and the disease results in severely blemished fruit which reduces its marketability. Transgenic ‘Duncan’ grapefruit trees expressing the antimicrobial attE gene were produced via Agrobacterium-mediated transformation. In in vitro leaf and greenhouse assays, several transgenic-lines had significantly lower susceptibility to E. fawcettii compared to the non-transformed control (P?0.0001). In the greenhouse studies, sporulation on all transgenic lines except 1 was significantly reduced (P?0.0001) but the level of sporulation over time did not correspond to disease severity ratings. Lesion size was also significantly reduced on transgenic lines compared to the non-transformed control (P?0.0001) and the least susceptible line A-23 had the smallest lesions, but in general there was no correlation between lesion size and disease susceptibility. The level of attE mRNA was inversely related to the number of copies detected by Southern blot. The least susceptible line had a single inserted copy of the attE transgene whereas more susceptible lines had multiple copies. Since the attacin mode of action was thought to be specific to Gram-negative bacteria, it was unexpected to find that there was a significant activity against E. fawcettii. 相似文献
7.
Niek Hias Anze Svara Johan Wannes Keulemans 《European journal of plant pathology / European Foundation for Plant Pathology》2018,150(2):515-520
Spinach is one of the most nutritious green-leaf vegetables. In the spinach production, diseases cause a significant loss in both yield and quality. Improving disease resistance is one of the major challenges in spinach breeding. Arabidopsis nucleoporin CONSTITUTIVE EXPRESSER OF PATHOGENESIS-RELATED GENES 5 (CPR5) functions as a negative regulator of plant cell death and immunity as cpr5 mutant exhibits spontaneous cell death and heightened immunity. In addition, CPR5 play a role in trichome development as the majority of cpr5 mutant trichomes are branchless whereas wild type trichomes are often three-branched. In the spinach genome, we identified a homolog of Arabidopsis CPR5, referred to as Spinacia oleracea CPR5 (SoCPR5). To investigate the function of SoCPR5, we introduced SoCPR5 into Arabidopsis cpr5 mutant. Our data showed that both spontaneous cell death and heightened immunity were suppressed in the SoCPR5-transgenic cpr5 mutants, verifying that SoCPR5 functions as its Arabidopsis counterpart in plant cell death and immunity. SoCPR5 also fully restored wild type trichome phenotype of the cpr5 mutant. Our study therefore indicates that the function of SoCPR5 is conserved between plant species and SoCPR5 can be applied for genetic manipulation of plant immunity in spinach. 相似文献
8.
Jaroslava Přibylová Karel Petrzik Josef Špak 《European journal of plant pathology / European Foundation for Plant Pathology》2009,124(1):181-185
Four Rhododendron hybridum plants (from cvs Moravanka and Don Juan), all exhibited symptoms of shortened axillary shoots, reduced leaves with
vein clearing and yellowing, undeveloped flowers, and general stunting in a rhododendron nursery garden in southern Bohemia
in 2007. Electron microscopy examination of ultra-thin sections revealed the presence of numerous polymorphic phytoplasma-like
bodies in the phloem tissue of leaf midribs and petioles. The phytoplasma etiology of this disease was further confirmed by
polymerase chain reaction (PCR) using universal phytoplasma primers. Restriction fragment length polymorphism (RFLP) analysis
of amplification products obtained with a R16F2/R16R2 primer pair from all symptomatic plants indicated the presence of phytoplasma
from the 16SrVI-A subgroup. A detailed comparison of the amplified sequences and phylogenetic analysis confirmed that the
phytoplasma belonged to the subgroup 16SrVI-A (clover proliferation phytoplasma group). This is the first report of the natural
occurrence of ‘Candidatus Phytoplasma trifolii’ in plants of Rhododendron hybridum. 相似文献
9.
Yigal Cohen Avia E. Rubin Gilar Kilfin 《European journal of plant pathology / European Foundation for Plant Pathology》2010,126(4):553-573
BABA induced local and systemic resistance in lettuce (Lactuca sativa) against the Oomycete Bremia lactucae. Structure-activity analysis showed no induced resistance by related amino-butanoic acids or β-alanine. The R-enantiomer of BABA induced resistance whereas the S-enantiomer did not, suggesting binding to a specific receptor. Other compounds known to be involved in SAR signaling, including abscisic acid, methyl-jasmonate, ethylene, sodium-salicylate and Bion® (BTH) did not induce resistance. Systemic translocation of 14C-BABA and systemic protection against downy mildew were tightly correlated. BABA did not affect spore germination, appressorium formation, or penetration of B. lactucae into the host. Epifluorescence and confocal microscopy revealed that BABA induced rapid encasement with callose of the primary infection structures of the pathogen, thus preventing it from further developing intercellular hyphae and haustoria. Invaded host cells treated with BABA did not accumulate phenolics, callose or lignin, or express HR. In contrast, cells of genetically-resistant cultivars accumulated phenolics, callose and lignin and exhibited HR within one day after inoculation. The callose synthesis inhibitor DDG did not inhibit callose encasement nor compromised the resistance induced by BABA. PR-proteins accumulated too late to be responsible for the induced resistance. DAB staining indicated that BABA induced a rapid accumulation of H2O2 in the penetrated epidermal host cells. Whether H2O2 stops the pathogen directly or via another metabolic route is not known. 相似文献
10.
Juan Carlos Ochoa-Sánchez Fannie Isela Parra-Cota Katia Aviña-Padilla John Délano-Frier Juan Pablo Martínez-Soriano 《Phytoparasitica》2009,37(4):381-384
Mexico is considered to be one of the centers of origin of grain amaranth species. Recently, plants with abnormal anatomical
features were observed in experimental fields established in Central Mexico. The most noticeable symptoms, which consisted
of excessive stem and bud proliferation, mosaics and unusual coloration, suggested that they might be phytoplasma-induced
disorders. Thus, different accessions of grain amaranth (Amaranthus hypochondriacus and A. cruentus) plants were subjected to polymerase chain reaction (PCR) analysis specifically designed to detect these pathogens. Two universal
phytoplasma-specific primer pairs were tested in a nested PCR assay, with primer pair P1/tint (followed by primer pair R16F2/R16R2). Further DNA sequencing analysis of the resulting amplicons indicated that these
phytoplasmas may be related to others already affecting important agricultural crops in Mexico, such as soybean. Data are
presented that disclose the etiology of these syndromes by the use of molecular techniques. To the best of our knowledge,
this finding constitutes the first report of a phytoplasma-related disease in grain amaranth. 相似文献
11.
Basil N Ziogas Dimitra Nikou Anastasios N Markoglou Anastasios A Malandrakis John Vontas 《European journal of plant pathology / European Foundation for Plant Pathology》2009,125(1):97-107
The molecular basis of resistance to benzimidazole fungicides with laboratory and field mutant isolates of Botrytis cinerea was investigated. After chemical mutagenesis with N-methyl-N-nitrosogouanidine (NMNG) two different benzimidazole-resistant phenotypes were isolated on media containing carbendazim or
a mixture of carbendazim and diethofencarb. The mutant isolates from the fungicide-mixture-containing medium were moderately
resistant to carbendazim with wild-type tolerance to diethofencarb while mutant isolates from carbendazim-containing medium
were highly resistant to carbendazim but sensitive to diethofencarb. The studied field isolates were highly resistant to benzimidazoles
and sensitive to diethofencarb. Study of fitness characteristics of benzimidazole highly-resistant isolates showed that the
resistance mutation(s) had no apparent effect on fitness-determining parameters. Contrary to this, the moderately benzimidazole-resistant
strains, with no increased diethofencarb sensitivity, had a significant reduction in certain ecological fitness-determining
characteristics. Analysis of the sequence of the β-tubulin gene revealed two amino acid replacements in the highly benzimidazole-resistant mutants compared to that of the wild-type
parent strain. One was the glutamic acid (GAG) to alanine (GCG) change at position 198 (E198A), identified in both laboratory
and field highly benzimidazole-resistant isolates, a mutation previously implicated in benzimidazole resistance. The second
was a novel benzimidazole resistance mutation of glutamic acid (GAG) to glycine (GGG) substitution at the same position 198
(E198G), identified in a highly benzimidazole-resistant laboratory mutant strain. Molecular analysis of the moderately benzimidazole-resistant
strains revealed no mutations at the β-tubulin gene. A novel diagnostic PCR-RFLP assay utilising a BsaI restriction site present in the benzimidazole-sensitive (E198) but absent in both resistant genotypes (E198G and E198A)
was developed for the detection of both amino acid replacements at the β-tubulin gene. 相似文献
12.
A detection method specific for Xanthomonas oryzae pv. oryzae, the pathogen responsible for bacterial blight of rice, was based on the polymerase chain reaction (PCR) and designed by amplifying
the 16S–23S rDNA spacer region from this bacterium. The nucleotide sequence of the spacer region between the 16S and 23S rDNA,
consisting of approximately 580-bp, from X. oryzae pv. oryzae, X. campestris pv. alfalfae, X. campestris pv. campestris, X. campestris pv. cannabis, X. campestris pv. citri, X. campestris pv. cucurbitae, X. campestris pv. pisi, X. campestris pv. pruni and X. campestris pv. vitians, was determined. The determined sequences had more than 95% identity. Therefore, a pair of primers, XOR-F (5′-GCATGACGTCATCGTCCTGT-3′)
and XOR-R2 (5′-CTCGGAGCTATATGCCGTGC-3′) was designed and found to specifically amplify a 470-bp fragment from all strains
of X. oryzae pv. oryzae isolated from diverse regions in Japan. No PCR product was amplified from X. campestris pathovars alfalfae, campestris, cannabis, carotae, cucurbitae, dieffenbachiae, glycines, pisi, pruni, vitians or zantedeschiae, except for pathovars citri, incanae and zinniae. The method could also detect the pathogen in infected rice leaves within 3 hr, at a detection limit of 4×101 cfu/ml.
Received 17 December 1999/ Accepted in revised form 10 April 2000 相似文献
13.
14.
Zhengnan Li Zhanmin Wu Hongguang Liu Xingan Hao Chunping Zhang Yunfeng Wu 《Journal of General Plant Pathology》2010,76(4):299-301
Spiraea salicifolia is widely grown in China as an ornamental plant, and its roots and young leaves have many medical uses. On the campus of
Northwest A&F University, we observed diseased S. salicifolia plants that had yellowed, dwarfed, deformed leaves and other symptoms resembling diseases caused by phytoplasma. This study
was aimed at determining the causal agent of the disease. On the basis of phytoplasma-specific DNA amplification by PCR, a
phytoplasma infection of S. salicifolia was confirmed. The phytoplasma was related to “Ca. Phytoplasma ziziphi” according to RFLP and phylogenetic analyses. This report is the first of phytoplasma infection of S. salicifolia in China. 相似文献
15.
The morphology of apple and pear stigma was investigated with confocal laser scanning microscopy and scanning electron microscopy.
The floral colonization process by Erwinia amylovora was studied with gfp-labelled bacteria and confocal laser scanning microscopy to allow the in vivo observation of the pathogen colonization on intact, viable plant tissues without any kind of staining of the specimens. The
interaction on the stigma between Erwinia amylovora and Pantoea agglomerans, both labelled with genes encoding for fluorescent proteins (DsRed-GFP), was also investigated. A stylar groove, covered
by papillae and dwelling from the stigma along the style, was visualized. In laboratory conditions, this groove was shown
to be an important way for E. amylovora migration towards the nectarthodes. Due to its anatomical structure the groove can sustain bacterial multiplication and thus
may play an important role on the interactions between the pathogen and the bacterial antagonist P. agglomerans. 相似文献
16.
The Rhizoctonia solani species consists of multinucleate isolates that belong to anastomosis groups AG1–AG3 and differ in virulence and host affinity. R. cerealis is a binucleate species of anastomosis group AG-D which causes sharp eyespot, a common plant disease in Poland. Rhizoctonia spp. is a ubiquitous soil pathogen that poses a significant threat for global crop production due to the absence of effective crop protection products. The aim of this study was to determine the virulence of R. solani and R. cerealis isolates towards Beta vulgaris, Zea mays, Triticum spelta and T. aestivum seedlings, to confirm the presence of endopolygalacturonase genes pg1 and pg5 in the genomes of the tested isolates and to evaluate the tested isolates’ sensitivity to triazole, strobilurin, imidazole and carboxamide fungicides. All tested isolates infected B. vulgaris seedlings. but none of them were virulent against Z. mays plants. R. solani isolates AG4 PL and AG2-2IIIB PL were characterized by the highest virulence (average infestation score of 2.37 and 2.53 points on a scale of 0–3 points) against sugar beet seedlings. The prevalence of infections caused by most of the analysed isolates (in particular R. solani AG4 J—11.8, and R. cerealis RC2—0.78) was higher in spelt than in bread wheat. The virulence of the analysed isolates was not correlated with the presence of pg1 and pg5 genes. The efficacy of the tested fungicides in controlling Rhizoctonia spp. infections was estimated at 100% (propiconazole + cyproconazole), 98.8% (penthiopyrad), 95.4% (tebuconazole) and 78.3% (azoxystrobin). 相似文献
17.
Aleš Lebeda Michaela Sedlářová Marek Petřivalský Jitka Prokopová 《European journal of plant pathology / European Foundation for Plant Pathology》2008,122(1):71-89
Plant pathogenic oomycetes, including biotrophic downy mildews and hemibiotrophs/necrotrophs such as Phytophthora and Pythium, cause enormous economic losses on cultivated crops. Lettuce breeders and growers face the threat of Bremia lactucae, the causal agent of lettuce downy mildew. This pathogen damages leaf tissues and lettuce heads and is also frequent on wild
Asteraceae plants. The interactions of Lactuca spp. with B. lactucae (abbr. lettuce–Bremia) display extreme variability, due to a long co-evolutionary history. For this reason, during the last 30 years, the lettuce–Bremia pathosystem has been used as a model for many studies at the population, individual, organ, tissue, cellular, physiological
and molecular levels, as well as on genetic variability and the genetics of host–parasite interactions. The first part of
this review summarizes recent data on host–parasite specificity, host variability, resistance mechanisms and genetics of lettuce–Bremia interactions. The second part focuses on the development infection structures. Phenotypic expression of infection, behaviour
of B. lactucae on leaf surfaces, the process of penetration, development of primary infection structures, hyphae and haustoria are discussed
in relation to different resistance mechanisms. In the third part, the components of host resistance and the variability of
defence responses are analysed. The role of reactive oxygen species (ROS), antioxidant enzymes, nitric oxide (NO), phenolic
compounds, reorganization of cytoskeleton, electrolyte leakage, membrane damage, cell wall disruption, hypersensitive reaction
and plant energetics are discussed in relation to defence responses. In general, the extreme variability of interactions between
lettuce and Bremia, and their phenotypic expression, results from diversity of the genetic background. Different mechanisms of resistance are
conditioned by an orchestra of defence responses at the tissue, cell, and molecular levels. The various events responsible
for defence involve a complex interaction of the processes and reactions mentioned above. This review also provides an overview
on the timing of pathogen development, host pathological anatomy, cytology and physiology of lettuce–Bremia associations. The significance of these factors on the expression of different resistance mechanisms (non-host and host resistance,
race-specific and race non-specific resistance, field resistance) is discussed. 相似文献
18.
Sylwia Magdalena Okoń Tomasz Ociepa 《European journal of plant pathology / European Foundation for Plant Pathology》2017,149(3):711-718
The aim of the present study was to determine the virulence structure of powdery mildew of oats (Blumeria graminis DC.f. sp. avena) in Poland in the years 2010–2013. For this purpose, powdery mildew isolates were collected from three experimental stations in Poland. To assess the virulence of the isolates, eight oat varieties with different responses to the pathogen were used. The results showed that a significant proportion of powdery mildew isolates found in Poland overcame the resistance genes of varieties Bruno (Pm6), Jumbo (Pm1) and Mostyn (Pm3). In contrast, lines Av1860 (Pm4), Am27 (Pm5) and Cc3678 (Pm2) were completely resistant to all pathogen isolates involved in the experiment. Changes constantly occurring in the powdery mildew population perfectly reflect diversity indexes, which were the smallest in the first year of observation, where in the following years these parameters were significantly higher. It is worth noting that the presence of powdery mildew is seasonal and local, which is reflected in the prevalence of the disease in a defined area of the country. 相似文献
19.
Peixin He Congcong Li Yingli Cai Ya Zhang Yinbing Bian Wei Liu 《Journal of General Plant Pathology》2018,84(1):65-69
In March 2013, pileus rot disease was first observed on cultivated Morchella importuna. Infected ascomata were covered by white, velvety mycelia mainly on the pileus, and the infection resulted in malformed fruiting bodies. The causal pathogen was identified as Diploöspora longispora based on its morphology and the internal transcribed spacer of its ribosomal DNA sequences. After inoculation of young ascomata with the isolates, the original symptoms were reproduced, and the same pathogen was reisolated from diseased ascomata. This is the first report of pileus rot disease on morels caused by D. longisporain China. 相似文献
20.
Vladimír Šašek Miroslava Nováková Petre I. Dobrev Olga Valentová Lenka Burketová 《European journal of plant pathology / European Foundation for Plant Pathology》2012,133(1):279-289
Resistance to infection in plants can be induced by treatment with various chemicals. One such compound is β-aminobutyric
acid (BABA). Its positive effect on disease resistance has been noted in several pathosystems. Here we demonstrate that treatment
with BABA protects Brassica napus plants from infection by the fungal pathogen Leptosphaeria maculans. Surprisingly, BABA also displayes in vitro antifungal activity against L. maculans with EC50 similar to the fungicide tebuconazole. Both spore germination and hyphal growth were affected. The toxic effect can be reverted
by addition of trypton to the culture medium. We hypothesised that BABA might inhibit inorganic nitrogen assimilation. Suppression
of disease progression in plants and antifungal activity in vitro was weaker for α-aminobutyric acid and negligible for γ-aminobutyric
acid. In contrast to a resistance inducer benzothiadiazole, the effect of BABA on disease development was nearly independent
of the timing of treatment, indicating possible antifungal activity in planta. On the other hand, quantification of multiple hormones and an expression analysis have shown that treatment with BABA induces
a synthesis of salicylic acid (SA) and expression of SA marker gene PR-1, but no evidence was observed for priming of SA responses to L. maculans. While we have not conclusively demonstrated how BABA suppresses the disease progression, our results do indicate that antifungal
activity is another mechanism by which BABA can protect plants from infection. 相似文献