''Mycosphaerella'' is a
genus
Genus (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In bino ...
of
ascomycota
Ascomycota is a phylum of the kingdom Fungi that, together with the Basidiomycota, forms the subkingdom Dikarya. Its members are commonly known as the sac fungi or ascomycetes. It is the largest phylum of Fungi, with over 64,000 species. The def ...
. With more than 10,000
species
A species () is often defined as the largest group of organisms in which any two individuals of the appropriate sexes or mating types can produce fertile offspring, typically by sexual reproduction. It is the basic unit of Taxonomy (biology), ...
, it is the largest genus of
plant pathogen
Plant diseases are diseases in plants caused by pathogens (infectious organisms) and environmental conditions (physiological factors). Organisms that cause infectious disease include fungi, oomycetes, bacteria, viruses, viroids, virus-like orga ...
fungi.
The following introduction about the fungal genus ''Mycosphaerella'' is copied (with permission) from the dissertation of W. Quaedvlieg (named: Re-evaluating ''Mycosphaerella'' and allied genera).
Species belonging to the fungal genus ''Mycosphaerella'' (1884) (''Capnodiales'', ''Dothideomycetes'') have evolved as
endophytes
An endophyte is an endosymbiont, often a bacterium or fungus, that lives within a plant for at least part of its life cycle without causing apparent disease. Endophytes are ubiquitous and have been found in all species of plants studied to date; ...
,
saprotroph
Saprotrophic nutrition or lysotrophic nutrition is a process of chemoheterotrophic extracellular digestion involved in the processing of decayed (dead or waste) organic matter. It occurs in saprotrophs, and is most often associated with fungi ...
s and symbionts, but mostly ''Mycosphaerella'' species are foliicolous plant pathogens which are the cause of significant economical losses in both temperate and tropical crops worldwide. The generic concept of Mycosphaerella is based on the type species of the genus, ''M. punctiformis'', which was introduced 130 years ago in order to describe small loculoascomycetes with few distinct morphological traits. Species belonging to ''Mycosphaerella'' were characterised as having pseudothecial ascomata that can be immersed or superficial, embedded in host tissue or