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L. Krstin S. Novak‐Agbaba D. Rigling M. Krajačić M. Ćurković Perica 《Plant pathology》2008,57(6):1086-1096
In order to improve understanding of its diversity, 338 isolates of Cryphonectria parasitica, the causal agent of chestnut blight, were sampled from 10 chestnut populations throughout chestnut‐growing coastal and continental areas of Croatia. Eighteen vegetative compatibility (VC) types were identified. The VC type EU‐1 was the most widespread, comprising 42·9% of the isolates, followed by EU‐2 (21%) and EU‐12 (14·2%). In respect to the occurrence of the main VC types, the C. parasitica populations in Croatia combined features of both northwestern and southeastern European populations. Perithecia and mating‐type ratios of approximately 1 : 1 were found in all populations, suggesting that sexual reproduction of the fungus is common in Croatia. Natural hypovirulence was also evident in all populations, with incidence of hypovirus‐infected isolates ranging from 12·7% in Istria‐Buje to 66·6% in the continental part of the country. A total of 36 hypovirus‐infected isolates sampled throughout Croatia were analysed in ORF‐A and ORF‐B by RT‐PCR/RFLP analysis. All viral isolates belonged to the Italian subtype of Cryphonectria hypovirus 1 (CHV‐1) and were closely related to the isolates found in other European countries. The RFLP patterns found were also identical or similar to the patterns of three isolates collected in Croatia 22 years ago, suggesting a slow evolution of the hypovirus. 相似文献
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Md. Iqbal Faruk Masatoshi Izumimoto Nobuhiro Suzuki 《Journal of General Plant Pathology》2008,74(6):425-433
The type virus of the family Hypoviridae,
Cryphonectria hypovirus 1 strain EP713 (CHV1-EP713), infects Cryphonectria parasitica, the filamentous causal fungus of chestnut blight, and reduces its virulence. This pathosystem serves as a model to study
fungus-mycovirus interactions. We previously developed a genetic screening protocol for host factors associated with symptom
induction by CHV1-EP713 and its mutants. In the procedure the standard field fungal isolate EP155 was transformed by cDNA
from a mild hypovirus mutant Cys(72), launching virus infection, and mutagenized by random plasmid insertion with pHygR conferring
hygromycin resistance. We now report an extension of the study to characterize different mutant strains, with different phenotypes
than their parental strain TCys(72)-1. TCys(72)-1 is moderately reduced in pigmentation and sporulation compared to the uninfected
wild-type strain EP155. Mutants sfb1, sfb2 and k202 were characterized biologically and molecularly in comparison to the previously
isolated mutant (namA) and the parental strain. These mutants harbored one (sfb1) or more copies (sfb2 and k202) of the mutagenic plasmid, pHygR.
The three mutants had similar biological attributes; that is, vegetative growth rate, conidiation and virulence (assay on
apples) was reduced on potato dextrose agar media, relative to the parental strain and pigmentation was the same or slightly
increased. Interestingly, viral dsRNA accumulation levels were apparently unaltered in these mutants. The screening method
was efficient for mining fungal mutants with unusual hypovirus symptoms. Further, characterization of the mutants provides
interesting insights into symptom induction by the hypovirus. 相似文献
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对照.此外,抗病品种酶活性高于中抗品种和感病品种;防御酶的活性与品种抗病性之间呈正相关,毒素作用后防御酶活性的变化可作为衡量板栗抗病性强弱的指标. 相似文献
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报道了海南1种球兰分布新记录萝藦科Asclepaidaceae匙叶球兰Hoya radicalis Tsiang et P.T.Li,凭证标本存放在华南农业大学林学院植物标本馆(CANT). 相似文献
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通过定性因素和定量指标体系相结合的方法对板栗疫病在广西的危险性进行评估,评估结果表明,此病害的危险性综合评价值为1.7128,属于中度危险性的林业有害生物。板栗疫病菌寄主范围广,此病在广西的分布已经相当广泛,但板栗疫病的病原菌不必补充为广西壮族自治区林业检疫性有害生物。通过采取栽培无病苗木、减少枝条和主干的伤口、削除枝条和主干的病斑和进行伤口的消毒、砍除重病枝等措施,可以有效地防治病害的发生。 相似文献
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A single 3 kb segment of double-stranded (dsRNA) was present in three of 30 Brazilian isolates of Cryphonectria cubensis . These dsRNA-containing isolates showed morphological characteristics suggestive of hypovirulence and were significantly less virulent than dsRNA-free isolates. One isolate, however, with morphological characteristics suggestive of hypovirulence, showed reduced virulence, but was free from dsRNA. Conversion of virulent isolates with normal morphology to a morphology associated with hypovirulence was achieved by pairing hypovirulent and virulent isolates of the same vegetative compatibility group (VCG). This suggests that dsRNA can be transmitted to isolates of the same vegetative compatibility group by hyphal anastomosis. Converted isolates exhibited the same hypovirulence-associated traits as those of the original dsRNA-containing hypovirulent isolates. These studies suggest that a single 3 kb segment of dsRNA alters both morphology and virulence by conferring hypovirulence on the pathogen; the first such report for Brazilian isolates of C. cubensis . 相似文献