Three genes for metabolism of the phytoalexin maackiain in the plant pathogen Nectria haematococca: Meiotic instability and relationship to a new gene for pisatin demethylase

Journal Article · Sun Mar 01 04:00:00 EST 1992 · Applied and Environmental Microbiology; (United States)

OSTI ID:7206401

Miao, V P.W.; Vanetten, H D ^[1]

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1. Cornell Univ., Ithaca, NY (United States)

Some isolates of the plant-pathogenic fungus Nectria haematococca mating population (MP) VI metabolize maackiain and medicarpin, two antimicrobial compounds (phytoalexins) synthesized by chickpea (Cicer arietinum L.). The enzymatic modifications by the fungus convert the phytoalexins to less toxic derivatives, and this detoxification has been proposed to be important for pathogenesis on chickpea. In the present study, loci controlling maackiain metabolism (Mak genes) were identified by crosses among isolates of N. haematococca MP VI that differed in their ability to metabolize the phytoalexin. Strains carrying Mak1 or Mak2 converted maackiain to 1a-hydroxymaackiain, while those with Mak3 converted it to 6a-hydroxymaackiain. Mak1 and Mak2 were unusual in that they often failed to be inherited by progeny. Mak1 was closely linked to Pda6, a new member in a family of genes in N. haematococca MP VI that encode enzymes for detoxification of pisatin, the phytoalexin synthesized by garden pea. Like Mak1, Pda6 was also transmitted irregularly to progeny. Although the unusual meiotic behaviors of some Mak genes complicate genetic analysis, identification of these genes should afford a more thorough evaluation of the role of phytoalexin detoxification in the pathogenesis of N. haematococca MP VI on chickpea.

• DOE Contract Number: FG02-89ER14038
• OSTI ID: 7206401
• Journal Information: Applied and Environmental Microbiology; (United States), Journal Name: Applied and Environmental Microbiology; (United States) Vol. 58:3; ISSN 0099-2240; ISSN AEMID
• Country of Publication: United States
• Language: English

Related Subjects

550200* -- Biochemistry
560300 -- Chemicals Metabolism & Toxicology
59 BASIC BIOLOGICAL SCIENCES
63 RADIATION, THERMAL, AND OTHER ENVIRON. POLLUTANT EFFECTS ON LIVING ORGS. AND BIOL. MAT.
ANTICOAGULANTS
CELL DIVISION
COUMARINS
DETOXIFICATION
DRUGS
ENZYMES
FUNGI
GENES
HEMATOLOGIC AGENTS
HETEROCYCLIC COMPOUNDS
MEIOSIS
METABOLISM
ORGANIC COMPOUNDS
ORGANIC OXYGEN COMPOUNDS
OXIDOREDUCTASES
OXYGENASES
PATHOGENESIS
PATHOGENS
PIGMENTS
PLANT DISEASES
PLANTS
PROTEINS
PSORALEN
VIRULENCE