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Izumi Y Kamei E Miyamoto Y Ohtani K Masunaka A Fukumoto T Gomi K Tada Y Ichimura K Peever TL Akimitsu K 《Phytopathology》2012,102(8):741-748
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Masunaka A Ohtani K Peever TL Timmer LW Tsuge T Yamamoto M Yamamoto H Akimitsu K 《Phytopathology》2005,95(3):241-247
ABSTRACT Two different pathotypes of Alternaria alternata cause Alternaria brown spot of tangerines and Alternaria leaf spot of rough lemon. The former produces the host-selective ACT-toxin and the latter produces ACR-toxin. Both pathogens induce similar symptoms on leaves or young fruits of their respective hosts, but the host ranges of these pathogens are distinct and one pathogen can be easily distinguished from another by comparing host ranges. We isolated strain BC3-5-1-OS2A from a leaf spot on rough lemon in Florida, and this isolate is pathogenic on both cv. Iyokan tangor and rough lemon and also produces both ACT-toxin and ACR-toxin. Isolate BC3-5-1-OS2A carries both genomic regions, one of which was known only to be present in ACT-toxin producers and the other was known to exist only in ACR-toxin producers. Each of the genomic regions is present on distinct small chromosomes, one of 1.05 Mb and the other of 2.0 Mb. Alternaria species have no known sexual or parasexual cycle in nature and populations of A. alternata on citrus are clonal. Therefore, the ability to produce both toxins was not likely acquired through meiotic or mitotic recombination. We hypothesize that a dispensable chromosome carrying the gene cluster controlling biosynthesis of one of the host-selective toxins was transferred horizontally and rearranged by duplication or translocation in another isolate of the fungus carrying genes for biosynthesis of the other host-selective toxin. 相似文献
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Alternaria alternata includes seven pathogenic variants, called pathotypes, which produce host-selective toxins (HSTs) as determinant factors for pathogenicity. The gene clusters for HST biosynthesis were identified from six pathotypes (Japanese pear, strawberry, tangerine, apple, tomato and rough lemon) and were found to reside on small chromosomes of <2.0 Mb in most strains tested. We isolated mutants lacking the small chromosomes from the strawberry, apple and tomato pathotypes and showed that the small chromosomes are dispensable for growth. In this review, we summarize our current understanding of the evolution of pathogenicity controlled by small, dispensable chromosomes in Alternaria alternata pathogens. 相似文献
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SALAMIAH Yukitaka FUKUMASA-NAKAI Hajime AKAMATSU Hiroshi OTANI Keisuke KOHMOTO Motoichiro KODAMA 《Journal of General Plant Pathology》2001,67(1):7-14
Several pathotypes of Alternaria alternata are known to produce host-specific toxins (HSTs) as agents of pathogenicity or virulence. However, investigations into the
genetic controls of HST biosynthesis and pathogenicity of Alternaria pathogens have been limited by the lack of a sexual stage in the life cycle of these pathogens. We report here the development
of a protoplast fusion system and its use for genetic analysis of HST production and specific pathogenicity of the tomato
pathotype of A. alternata that produces AAL-toxin as a HST. Drug-resistant transformants have been isolated by genetic transformation of nonpathogenic
A. alternata (strain O-94) and A. alternata tomato pathotype (strain As-27) with vectors conferring resistance to hygromycin B and geneticin, respectively. Protoplasts
of the respective transformants were fused by polyethylene glycol treatment or electrofusion. Fusion products were selected
by culturing in the presence of both hygromycin B and geneticin, then confirmed by amplification using a polymerase chain
reaction with specific primers to the transforming drug-resistance genes. Stable fusants were purified by successive subcultures
on selective medium and single-spore isolation. The resultant stable fusants, probably inter-strain hybrids, had the same
pathogenicity and toxin production as the wild-type strain As-27. These results suggest that protoplast fusion has potential
applications for genetic analysis of A. alternata pathogens.
Received 8 September 2000/ Accepted in revised form 27 October 2000 相似文献
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中国柑橘黑腐病和褐斑病病原菌的系统发育分析 总被引：4，自引：0，他引：4
近些年链格孢属真菌的分类有了长足的进展,但柑橘褐斑病和黑腐病的病原却还是存在着一些争议。本研究从中国柑橘果实上收集了49株黑腐病菌菌株,并选取了8株从柑橘叶片上分离的具代表性的褐斑病菌菌株,基于Alta1 、endoPG、LSU、OPA10-2、OPAl-3和OPA2-1 等6个基因位点串联序列构建系统发育树。结果表明,柑橘黑腐病和褐斑病都可由不止一种链格孢菌引起,均以Alternaria alternata为主。两种病害的病原菌之间不能通过该系统发育树区分,但在致病性上存在差异,且能通过扩增ACT毒素合成基因进行区分。为了使两种病害的病原更加方便阐述,作者建议以它们的主要类群对其进行命名,柑橘褐斑病病原学名还是遵循前人的称呼,为the tangerine pathotype of A. alternata,即链格孢菌橘致病型,而柑橘黑腐病病原应为A. alternata,即链格孢菌。 相似文献
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ABSTRACT Alternaria alternata apple pathotype (previously A. mali) causes Alternaria blotch on susceptible apple cultivars through the production of a host-specific toxin, AM-toxin. Identification of some Alternaria species, especially those that produce host-specific toxins, has been extremely difficult due to a high level of variability which extends even to nonpathogenic isolates. We have recently cloned and characterized a gene (AMT) that plays a crucial role in AM-toxin biosynthesis and demonstrated that it is only present in isolates of A. alternata apple pathotype. Using primers designed for the AMT gene, we developed a polymerase chainreaction-based method to specifically detect AM-toxin producing isolates of A. alternata apple pathotype. 相似文献
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近些年链格孢属真菌的分类有了长足的进展,但柑橘褐斑病和黑腐病的病原却还是存在着一些争议。本研究从中国柑橘果实上收集了49株黑腐病菌菌株,并选取了8株从柑橘叶片上分离的具代表性的褐斑病菌菌株,基于Alta1 、endoPG、LSU、OPA10-2、OPAl-3和OPA2-1 等6个基因位点串联序列构建系统发育树。结果表明,柑橘黑腐病和褐斑病都可由不止一种链格孢菌引起,均以Alternaria alternata为主。两种病害的病原菌之间不能通过该系统发育树区分,但在致病性上存在差异,且能通过扩增ACT毒素合成基因进行区分。为了使两种病害的病原更加方便阐述,作者建议以它们的主要类群对其进行命名,柑橘褐斑病病原学名还是遵循前人的称呼,为the tangerine pathotype of A. alternata,即链格孢菌橘致病型,而柑橘黑腐病病原应为A. alternata,即链格孢菌。 相似文献
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ABSTRACT Phylogenetic analysis revealed that isolates of Alternaria alternata causing black rot of citrus were associated with six well-supported evolutionary lineages. Isolates recovered from brown spot lesions on Minneola tangelo, leaf spot lesions on rough lemon, and healthy citrus tissue and noncitrus hosts were related closely to isolates from black-rotted fruit. Phylogenies estimated independently from DNA sequence data from an endopolygalacturonase gene (endoPG) and two anonymous regions of the genome (OPA1-3 and OPA2-1) had similar topologies, and phylogenetic analysis was performed on the combined data set. In the combined phylogeny, isolates from diverse ecological niches on citrus and noncitrus hosts were distributed in eight clades. Isolates from all lineages, regardless of ecological or host association, caused black rot in fruit inoculation assays, demonstrating that small-spored Alternaria isolates associated with different ecological niches on citrus and other plant hosts are potential black rot pathogens. These data also indicated that the fungi associated with black-rotted fruit do not form a natural evolutionary group distinct from other Alternaria pathogens and saprophytes associated with citrus. The use of the name A. citri to describe fungi associated with citrus black rot is not justified and it is proposed that citrus black rot fungi be referred to as A. alternata. 相似文献
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SALAMIAH Hajime AKAMATSU Yukitaka FUKUMASA-NAKAI Hiroshi OTANI Motoichiro KODAMA 《Journal of General Plant Pathology》2001,67(2):97-105
The genetic controls of host-specific toxin (HST) biosynthesis and the pathogenicity of A. alternata pathogens have been limited by the asexual nature of the life cycle of these fungi. We used a protoplast fusion system for
A. alternata to analyze the genetics of HST production and its relation to the specific pathogenicity of these pathogens. Drug-resistant
transformants were isolated by genetic transformation, using vectors conferring resistance to hygromycin B and geneticin,
for the A. alternata apple pathotype (AM-toxin producer) and A. alternata tomato pathotype (AAL-toxin producer), respectively. Protoplasts of the respective transformants were fused by electrofusion.
The majority of resultant stable fusants produced both AM- and AAL-toxins and were pathogenic to susceptible cultivars of
both apple and tomato. Pulsed-field gel electrophoresis analysis demonstrated that these fusants (or hybrids) carried small
1.7-and 1.1-Mb chromosomes, characteristic of the parental strains of the apple and tomato pathotypes, respectively. Detection
of the AMT gene, involved in AM-toxin biosynthesis, by polymerase chain reaction revealed that all fusants pathogenic to apple maintained
this gene. Microfluorimetry analysis using propidium iodide staining suggested that the fusants might be diploid.
Received 14 November 2000/ Accepted in revised form 11 December 2000 相似文献
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Megumu Tanahashi Takashi Nakano Hajime Akamatsu Motoichiro Kodama Hiroshi Otani Kumiko Osaki-Oka 《European journal of plant pathology / European Foundation for Plant Pathology》2016,145(4):787-795
A disease caused by Alternaria alternata occurred on the leaves of European pear cultivar Le Lectier in Niigata Prefecture, Japan, and was named black spot of European pear. In conidial inoculation tests, the causal pathogen induced not only small black lesions on the leaves of European pear cultivar Le Lectier, but severe lesions on the leaves of apple cultivar Red Gold, which is susceptible to the A. alternata apple pathotype (previously called A. mali) causing Alternaria blotch of apple. Interestingly, the apple pathotype isolate showed the same pathogenicity as the European pear pathogen. HPLC analysis of the culture filtrates revealed that A. alternata causing black spot of European pear produced AM-toxin I, known as a host-specific toxin of the A. alternata apple pathotype. AM-toxin I induced veinal necrosis on leaves of Le Lectier and General Leclerc cultivars, both susceptible to the European pear pathogen, at 5?×?10?7 M and 10?6 M respectively, but did not affect leaves of resistant cultivars at 10?4 M. PCR analysis with primers that specifically amplify the AM-toxin synthetase gene detected the product of expected size in the pathogen. These results indicate that A. alternata causing black spot of European pear is identical to that causing Alternaria blotch of apple. This is the first report of European pear disease caused by the A. alternata apple pathotype. This study provides a multiplex PCR protocol, which could serve as a useful tool, for the epidemiological survey of these two diseases in European pear and apple orchards. 相似文献
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Daisuke Yamagishi Hajime Akamatsu Hiroshi Otani Motoichiro Kodama 《Journal of General Plant Pathology》2006,72(5):323-327
Host-specific AAL-toxins and mycotoxin fumonisins are structurally related and were originally isolated from the tomato pathotype
of Alternaria alternata and from Fusarium verticillioides, respectively. Previous reports on the production of fumonisin derivatives by the tomato pathotype suggested a possible involvement
in the pathogenicity of the pathogen. Here, we have evaluated the role of fumonisin in A. alternata–tomato interactions. The results indicate that highly pathogenic isolates of A. alternata tomato pathotype produce AAL-toxin as the sole toxin, strongly implicating it as a pathogenicity factor. The related compound,
fumonisin, is also toxigenic and has infection-inducing activity on susceptible tomato plants. 相似文献
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Kazuya Akimitsu Takashi Tsuge Motoichiro Kodama Mikihiro Yamamoto Hiroshi Otani 《Journal of General Plant Pathology》2014,80(2):109-122
Seven diseases caused by pathotypes of Alternaria alternata, which produced host-selective toxins (HSTs), a diverse group of low-molecular-weight secondary metabolites, are known, and each HST has an essential role as a determinant of pathogenicity in all interactions between the plant host and A. alternata. Although these HST-producing pathotypes are morphologically indistinguishable, each has a distinct host range and can be distinguished by its specificity on the respective host plant, hence their designation as pathotypes of A. alternata. In 1933, Tanaka made the first discovery of a HST; fungus-free culture filtrates of A. kikuchiana (now called A. alternata Japanese pear pathotype) were toxic to susceptible cultivar Nijisseiki, but not to resistant cultivars. Over the 80 years since then, the structure of HST molecules, target sites and mode of actions of HSTs, and the molecular genetics of HST production regulating by supernumerary chromosomes encoding HST gene clusters have been studied extensively. We focus this review on studies of low-molecular-weight HSTs produced by A. alternata and give an overview of various types of HST studies. 相似文献
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Roxana Y. Parada Kumiko Oka Daisuke Yamagishi Motoichiro Kodama Hiroshi Otani 《Physiological and Molecular Plant Pathology》2007,71(1-3):48-54
It has been reported that Alternaria brassicae, the causal agent of gray leaf spot in Brassica plants, produces a host-specific or host-selective toxin (HSTs) identified as destruxin B. In this study, the role of destruxin B in infection of the pathogen was investigated. Destruxin B purified from culture filtrates (CFs) of A. brassicae induced chlorosis on host leaves at 50–100 μg ml−1, and chlorosis or necrosis on non-host leaves at 250–500 μg ml−1. Destruxin B was detected in spore germination fluids (SGFs) on host and non-host leaves, but not in a sufficient amount to exert toxicity to host plants. When spores of non-pathogenic A. alternata were combined with destruxin B at 100 μg ml−1 and inoculated on the leaves, destruxin B did not affect the infection behavior of the spores. Interestingly, SGF on host leaves allowed non-pathogenic spores to colonize host leaves. Moreover, a high molecular weight fraction (>5 kDa) without destruxin B obtained by ultrafiltration of SGF had host-specific toxin activity and infection-inducing activity. From these results, we conclude that destruxin B is not a HST and does not induce the accessibility of the host plant which is essential for colonization of the pathogen. In addition, the results with SGF imply that a high molecular weight HST(s) is involved in the host–pathogen interaction. 相似文献
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Yumiko Yamasaki Hitoshi Kunoh Hiroyuki Yamamoto Kazuya Akimitsu 《Journal of General Plant Pathology》2007,73(3):168-179
Volatile compounds of plants, including monoterpenes, are a possible source of signal molecules that induce defense systems
to protect plants from tissue damage. Volatile compounds from rough lemon leaves were trapped by solid-phase microextraction
fibers in sealed vials, and subsequent gas chromatography–mass spectrometry and gas chromatography analyses identified the
profile of the major components, mainly various monoterpenes. Among several monoterpenes examined, citral, citronellal, and
linalool significantly inhibited the spore germination and hyphal growth of Alternaria alternata. The effect of linalool was fungistatic, while the effects of citral and citronellal were partially fungicidal. Wounding
of rough lemon leaves induced a significant increase in release of monoterpenes. The release of linalool was the most abundant
and was 14.5 times that of unwounded rough lemon leaves. Unlike the wounding treatment, microbe attack did not significantly
change monoterpene releases, and there was statistically no difference found in the peak areas from microbe-treated and untreated
leaves. Linalool, limonene, and β-pinene also had insect-repellant effects on wild-type Drosophila melanogaster. Expression patterns of defense-related genes in rough lemon and rice significantly changed after treatment with vapors of
monoterpene volatiles. Taking these results together, monoterpene volatiles are likely to play roles in the defense of rough
lemon against microbe and insect pathogens. 相似文献
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