Polyphasic reassessment of a yellow rice fungus, Penicillium toxicarium

Abstract

From historical strain records, Penicillium citreonigrum NBRC 4692 was originally isolated as the toxigenic fungus responsible for the yellow rice incident in Japan in 1937. The fungus was named Penicillium toxicarium by I. Miyake, which was considered invalid due to the lack of a Latin diagnosis. Initially, it was named Penicillium sp. by Miyake et al. in 1940. Subsequently, P. toxicarium, which was erroneously cited as synonym of P. citreo-viride, was validated by C. Ramírez in 1982 with a Latin diagnosis and type designation (CBS 351.51). Later, CBS 351.51 was assigned to Penicillium trzebinskii by Houbraken et al. in 2014. In 2016, P. toxicarium was treated as a synonym of Penicillium citreosulfuratum based on a conclusion of molecular phylogenetic analysis. Recently, we discovered the taxonomic and nomenclatural short communication (in Japanese) by I. Miyake in 1947 on P. toxicarium sp. nov. with its Latin description and four illustrations but lacking the type designation. In this paper, we re-examined strain NBRC 4692 for its current taxonomic position based on morphological characteristics and molecular phylogenetic analysis. NBRC 4692 (received from I. Miyake in 1951) has been found to have the same morphological characteristics as P. toxicarium, as was shown in Miyake's diagnosis in 1947. Phylogenetic analysis revealed that the NBRC strain belongs to a unique clade, different from the clade comprising P. citreosulfuratum strains. As a conclusion, herein, P. toxicarium I. Miyake (1947) is reinstated as a correct name with the lectotype designation.