Six new genes required for production of T-toxin, a polyketide determinant of high virulence of Cochliobolus heterostrophus to maize.

摘要: Southern Corn Leaf Blight, one of the worst plant disease epidemics in modern history, was caused by Cochliobolus heterostrophus race T, which produces T-toxin, a determinant high virulence to maize carrying Texas male sterile cytoplasm. The genetics T-toxin production is complex and evolutionary origin associated genes uncertain. It known that ability produce requires three encoded at two unlinked loci, Tox1A Tox1B, map breakpoints reciprocal translocation. DNA with Tox1B sums about 1.2 Mb A+T rich, repeated not found less virulent O or other species. Here, we describe identification targeted deletion six additional genes, mapping Tox1B. Mutant screens indicate all are involved maize. nine Tox1 encode polyketide synthases (PKS), decarboxylase, five dehydrogenases, unknown protein. Only have similar phylogenetic profile. To trace history core PKS, from more than 100 Dothideomycete species were screened for homologs. An ortholog (60% identity) confirmed Didymella zeae-maydis, PM-toxin, structure biological specificity as T-toxin. species, dung ascomycete Delitschia winteri harbored paralog. unresolved distinctive gene signature PKS (fast-evolving, discontinuous taxonomic distribution) leaves open question lateral vertical transmission.