Title: The genomes of Mycosphaerella graminicola and M. fijiensis Authors
|Kema, Gert Hj -|
Submitted to: Book Chapter
Publication Type: Book / Chapter
Publication Acceptance Date: April 28, 2014
Publication Date: N/A
Technical Abstract: Mycosphaerella graminicola and M. fijiensis are two of the most important pathogens of wheat and banana, respectively. Both pathogens cause economically significant diseases that can be controlled with fungicides, but have rapidly developed resistance rendering chemical control less than satisfactory. Increasing host resistance is possible for wheat but most major resistance genes break down rapidly in the field. Breeding banana for increased resistance is extremely difficult because modern cultivars are sterile triploids. High genetic variability within populations of the pathogens, rapid evolution of fungicide resistance, and limited availability and effectiveness of resistance genes help make septoria tritici blotch of wheat and black Sigatoka (or black leaf streak) of banana persistent and economically challenging diseases. To better understand these diseases and provide the basis for future control, the genomes of both pathogens were sequenced. The genome of M. graminicola was unusual because the eight smallest of its 21 chromosomes were very different from the core 13 for every statistic measured. These eight chromosomes were shown to be dispensable in previous work, i.e., they could be lost with no obvious effect on fitness, and probably were acquired by horizontal transfer from an unknown donor species more than 10,000 years ago. The genome of M. fijiensis was greatly expanded in size due to amplification of transposons, but why this occurred is not known. Analysis of effector proteins produced by the M. fijiensis genome identified one that was similar to a putative homolog in a tomato pathogen and could be recognized by a tomato resistance gene indicating that non hosts may provide potential sources of new resistance.