Since its discovery more than 110 years ago, Valsa canker has emerged as a devastating disease of apple in East Asia. However, our understanding of this disease, particularly the identity of the causative agents, has been in a state of confusion. Here we provide a synopsis for the current understanding of Valsa canker and the taxonomy of its causal agents. We highlight the major changes concerning the identity of pathogens and the conflicting viewpoints in moving to “One Fungus = One Name” system for this group of fungal species. We compiled a list of 21 Cytospora species associated with Malus hosts worldwide and curated 12 of them with rDNA-ITS sequences. The inadequacy of rDNA-ITS in discriminating Cytospora species suggests that additional molecular markers, more intraspecific samples and robust methods are required to achieve reliable species recognition.

Type 2C protein phosphatases (PP2Cs) are monomeric protein serine/threonine phosphatases that play various roles in eukaryotic organisms. In this study, we characterized the PP2C encoded by FgPTC1 in Fusarium graminearum, the major causal agent of Fusarium head blight on wheat and barley. We found that deletion of FgPTC1 delays the mycelium growth of F. graminearum in response to lithium. Consistently, FgPTC1 complemented the function of ScPTC1 in lithium toxicity in Saccharomyces cerevisiae. Furthermore, we showed that deletion of FgPTC1 attenuated the virulence of F. graminearum on wheat. Therefore, FgPTC1 plays an important role in regulating the hyphal growth and virulence of F. graminearum.

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