First record of the genus Restiosporium (Websdaneaceae, Ustilaginales) outside Australasia: documenting R. spathacei in Thailand

The genus Restiosporium consists of 21 species on hosts in the Restionaceae. It was known only from Australia and New Zealand. Restiosporium is reported here for the first time outside Australasia, based on a specimen of R. spathacei on Dapsilanthus disjunctus from Thailand. A description and illustrations are provided for this smut fungus. Dapsilanthus disjunctus is a new host plant for Restiosporium spathacei.

Transcription factor UvMsn2 is important for vegetative growth, conidiogenesis, stress response, mitochondrial morphology and pathogenicity in the rice false smut fungus Ustilaginoidea virens

Transcription factors (TFs) play critical roles in the control of development and pathogenicity of phytopathogens by directly or indirectly regulating the expression of downstream genes. Here, we identified and characterized a zinc finger TF UvMsn2 in Ustilaginoidea virens, a homolog of MoMsn2 from the rice blast fungus. Heterogenous complementation assay revealed that UvMsn2 fully restored the defects of the ∆Momsn2 mutant in vegetative growth, conidiation and pathogenicity. Deletion of UvMsn2 in U. virens led to a reduction of the pathogen in vegetative growth, aerial hyphae and conidiation. Additionally, the ∆Uvmsn2 mutant displayed defects in conidial morphology and germination, as well as mitochondrial morphology. Pathogenicity and toxicity assays revealed that the ∆Uvmsn2 mutant was non-pathogenic and less inhibitory to rice seed germination. The ∆Uvmsn2 mutant showed different sensitivity to various stresses. Further microscopic examination found that UvMsn2 was localized in both cytosol and nucleus, and translocated from cytosol to nucleus under the treatment of NaCl. Our results demonstrate that UvMsn2 is a critical TF that regulates the vegetative growth, conidiogenesis, stress response, mitochondrial morphology and virulence in the rice false smut fungus.

Entyloma eranthidis sp. nov. on Eranthis longistipitata from Uzbekistan

A new smut fungus, Entyloma eranthidis on Eranthis longistipitata from Uzbekistan, revealed by molecular, morphological, and ecological evidence, is described and illustrated. It differs from all other species of Entyloma by host specialization on Eranthis and by having longer (≤35(–38) μm) spores and thicker (≤10(–12) μm) spore walls. ITS rDNA sequence analysis indicates that the new species does not cluster with other species of Entyloma on Ranunculaceae.

Thecaphora solani (potato smut).

T. solani is a smut fungus attacking tubers and underground stems of Solanum, including potato [Solanum tuberosum] and tomato [Solanum lycopersicum], in the Andean region of South America. It is not restricted to the higher, cooler elevations, but has been a problem in coastal Peru (Bazan de Segura 1960; Zachmann and Baumann, 1975) and also occurs in Mexico. It may be transported in infected tubers and planting material and, very likely, on their surfaces if they become contaminated with the spores. The fungus survives in the soil and is difficult to eradicate; it can infect at least one common solanaceous weed. Losses of 80% or more have been reported in susceptible varieties. EPPO lists it as an A1 plant pest (OEPP/EPPO, 1979).