Page Banner

United States Department of Agriculture

Agricultural Research Service

Research Project: MOLECULAR AND GENETIC MECHANISMS OF FUNGAL DISEASE RESISTANCE IN GRAIN CROPS

Location: Crop Production and Pest Control Research

Title: Mycosphaerella comparative genomics reveals chromosome dynamics, genome evolution and stealth pathogenesis

Authors
item Goodwin, Stephen
item Dhillon, Braham -
item Ben M"barek, Sarrah -
item Grigoriev, Igor -
item Kema, Gert H. -

Submitted to: American Phytopathological Society Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: May 1, 2011
Publication Date: N/A

Technical Abstract: Mycosphaerella graminicola causes septoria tritici blotch, one of the most important diseases of wheat worldwide. Previous analyses showed that populations of this species are extremely variable and that polymorphisms for chromosome length and number can be generated during meiosis. To better understand the genetic basis for genomic plasticity, the genomes of M. graminicola and the related banana pathogen M. fijiensis were sequenced by the Joint Genome Institute. The finished genome of M. graminicola had 13 core chromosomes and a dispensome of eight chromosomes that were different from those in the core for every parameter measured. Comparison with sequences of related species revealed that the dispensome probably originated by ancient horizontal transfer from an unknown donor, and has been maintained through at least one speciation event. Content (genes and transposons) on the core set is conserved among species and 13 seems to be the basic chromosome number in Mycosphaerella. Content on the eight dispensable chromosomes is conserved within populations but not within individuals, and some parts of the dispensome occur at lower frequency than others. Species of Mycosphaerella contain fewer genes for cell wall-degrading enzymes compared to other plant pathogens and may metabolize proteins rather than carbohydrates during the biotrophic phase of growth. Stealth pathogenicity may have evolved to avoid detection by the host, possibly from an endophytic ancestor.

Last Modified: 4/19/2014
Footer Content Back to Top of Page