The global regulator LaeA controls biosynthesis of host-specific toxins, pathogenicity and development of Alternaria alternata pathotypes

2016 ◽  
Vol 82 (3) ◽  
pp. 121-131 ◽  
Author(s):  
Kazumi Takao ◽  
Yasunori Akagi ◽  
Takashi Tsuge ◽  
Yoshiaki Harimoto ◽  
Mikihiro Yamamoto ◽  
...  
Keyword(s):  
Alternaria Alternata ◽  
Global Regulator ◽  
Host Specific Toxins

scholarly journals A Polymerase Chain Reaction-Based Method to Specifically Detect Alternaria alternata Apple Pathotype (A. mali), the Causal Agent of Alternaria Blotch of Apple

2000 ◽  
Vol 90 (9) ◽  
pp. 973-976 ◽  
Author(s):  
R. D. Johnson ◽  
L. Johnson ◽  
K. Kohmoto ◽  
H. Otani ◽  
C. R. Lane ◽  
...  
Keyword(s):  
Polymerase Chain Reaction ◽  
Alternaria Alternata ◽  
Crucial Role ◽  
Chain Reaction ◽  
Alternaria Species ◽  
Apple Cultivars ◽  
Polymerase Chain ◽  
Alternaria Blotch ◽  
High Level ◽  
Host Specific Toxins

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.

scholarly journals A Conditionally Dispensable Chromosome Controls Host-Specific Pathogenicity in the Fungal Plant Pathogen Alternaria alternata

Genetics ◽  
2002 ◽  
Vol 161 (1) ◽  
pp. 59-70 ◽  
Author(s):  
Rieko Hatta ◽  
Kaoru Ito ◽  
Yoshitsugu Hosaki ◽  
Takayoshi Tanaka ◽  
Aiko Tanaka ◽  
...  
Keyword(s):  
Gene Cluster ◽  
Filamentous Fungus ◽  
Plant Pathogen ◽  
Alternaria Alternata ◽  
Japanese Pear ◽  
Pathogenic Variants ◽  
Dispensable Chromosome ◽  
Fungal Plant Pathogen ◽  
Multiple Copies ◽  
Host Specific Toxins

Abstract The filamentous fungus Alternaria alternata contains seven pathogenic variants (pathotypes), which produce host-specific toxins and cause diseases on different plants. Previously, the gene cluster involved in host-specific AK-toxin biosynthesis of the Japanese pear pathotype was isolated, and four genes, named AKT genes, were identified. The AKT homologs were also found in the strawberry and tangerine pathotypes, which produce AF-toxin and ACT-toxin, respectively. This result is consistent with the fact that the toxins of these pathotypes share a common 9,10-epoxy-8-hydroxy-9-methyl-decatrienoic acid structural moiety. In this study, three of the AKT homologs (AFT1-1, AFTR-1, and AFT3-1) were isolated on a single cosmid clone from strain NAF8 of the strawberry pathotype. In NAF8, all of the AKT homologs were present in multiple copies on a 1.05-Mb chromosome. Transformation-mediated targeting of AFT1-1 and AFT3-1 in NAF8 produced AF-toxin-minus, nonpathogenic mutants. All of the mutants lacked the 1.05-Mb chromosome encoding the AFT genes. This chromosome was not essential for saprophytic growth of this pathogen. Thus, we propose that a conditionally dispensable chromosome controls host-specific pathogenicity of this pathogen.

scholarly journals Chitosan Effects on Blackmold Rot and Pathogenic Factors Produced by Alternaria alternata in Postharvest Tomatoes

2000 ◽  
Vol 125 (6) ◽  
pp. 742-747 ◽  
Author(s):  
M.V. Bhaskara Reddy ◽  
Paul Angers ◽  
Francois Castaigne ◽  
Joseph Arul
Keyword(s):  
Enzyme Activity ◽  
Lycopersicon Esculentum ◽  
Alternaria Alternata ◽  
Chelating Agents ◽  
Pectate Lyase ◽  
Host Interactions ◽  
Control Fruit ◽  
Pathogenic Factors ◽  
Host Specific Toxins ◽  
Polygalacturonase Activity

Stem scar application of chitosan inhibited growth and production of pathogenic factors by blackmold rot [Alternaria alternata (Fr.:Fr.) Keissl.] in challenged tomato (Lycopersicon esculentum Mill.) fruit stored at 20 °C for 28 days. Blackmold lesions were visible within 4 days of inoculation in control fruit, compared with >7 days in chitosantreated fruit. Macerating enzyme activity (polygalacturonase, pectate lyase, and cellulase) in the tissue in the vicinity of the lesions was <50% in chitosan-treated fruit compared with control fruit. Chitosan also inhibited production of oxalic and fumaric acids (chelating agents) and host-specific toxins such as alternariol and alternariol monomethylether by the fungus. The pH of the infected tissue decreased from 4.7 to 4.0 in the control fruit, the optimum for polygalacturonase activity, while the pH of chitosan-treated fruit remained at 4.6. In addition, chitosan also induced production of rishitin (a phytoalexin) in tomato tissue. Such chitosan-pathogen-host interactions may be exploited in the control of postharvest pathogens of fresh fruit and vegetables.

scholarly journals Multiple Epoxide Hydrolases in Alternaria alternata f. sp. lycopersici and Their Relationship to Medium Composition and Host-Specific Toxin Production

1999 ◽  
Vol 65 (6) ◽  
pp. 2388-2395 ◽  
Author(s):  
Christophe Morisseau ◽  
Barney L. Ward ◽  
David G. Gilchrist ◽  
Bruce D. Hammock
Keyword(s):  
Molecular Mass ◽  
Alternaria Alternata ◽  
Epoxide Hydrolase ◽  
Pathogenic Fungus ◽  
Toxin Production ◽  
Medium Composition ◽  
Aal Toxin ◽  
Host Specific Toxins ◽  
Aal Toxins

ABSTRACT The production of Alternaria alternata f. sp.lycopersici host-specific toxins (AAL toxins) and epoxide hydrolase (EH) activity were studied during the growth of this plant-pathogenic fungus in stationary liquid cultures. Media containing pectin as the primary carbon source displayed peaks of EH activity at day 4 and at day 12. When pectin was replaced by glucose, there was a single peak of EH activity at day 6. Partial characterization of the EH activities suggests the presence of three biochemically distinguishable EH activities. Two of them have a molecular mass of 25 kDa and a pI of 4.9, while the other has a molecular mass of 20 kDa and a pI of 4.7. Each of the EH activities can be distinguished by substrate preference and sensitivity to inhibitors. The EH activities present at day 6 (glucose) or day 12 (pectin) are concomitant with AAL toxin production.

Structure of AF-toxin II, one of the host-specific toxins produced by alternaria alternata strawberry pathotype

1986 ◽  
Vol 27 (24) ◽  
pp. 2753-2756 ◽  
Author(s):  
Shin-ichi Nakatsuka ◽  
Kazuo Ueda ◽  
Toshio Goto ◽  
Mikihiro Yamamoto ◽  
Syoyo Nishimura ◽  
...  
Keyword(s):  
Alternaria Alternata ◽  
Host Specific Toxins
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