PATHOVARS OR FORMAE SPECIALES OF MICROBOTRYUM-VIOLACEUM DIFFER IN ELECTROPHORETIC KARYOTYPE

Isolates of the basidiomycete phytopathogen, Microbotryum violaceum (P ers.: Pers.) Deml & Oberw. (Ustilago violacea [Pers.] Roussel), are re stricted in their host range to one or a few species of Caryophyllacea e (Pinks). Thus, the 200-plus species that serve as hosts for M. viola ceum define pathovars or formae speciales of the fungus. For both a(1) and a(2) sporidial mating-type strains of different formae speciales of M. violaceum electrophoretic karyotypes and chromosomal polymorphis ms were examined using CHEF gel analysis and 12-15 distinct bands were visualized. The bands, representing intact chromosomes, ranged in siz e from ca. 0.97 to 5.7 megabase pairs (Mb) for the pathovar that infec ts Silene latifolia. Their chromosome numbers were consistent with the numbers of linkage groups (14-20) identified by genetic analysis. Sev eral size polymorphisms were detected within this forma specialis, and some dramatic polymorphisms were observed between different formae sp eciales. Southern analyses with the genes for M. violaceum gamma-tubul in and TATA-box binding protein (TFIID) as probes confirmed the size p olymorphisms among the respective karyotypes of the strains.