Brown leaf spot disease caused by Alternaria spp. is among the most common diseases in potato crops. Typical brown spot symptoms were observed in commercial potato-cultivated areas of northern Korea during June 2021–2022. In total, 77 isolates were collected, and based on sequence analysis of the internal transcribed spacer (ITS) region, the collected isolates were identified as Alternaria spp. (83.1%). Phylogenetic analysis revealed that a majority of these isolates clustered within a clade that included A. alternata. Additionally, the ITS region and rpb2 yielded the most informative sequences for the identification of A. alternata. Pathogenicity tests confirmed that the collected pathogens elicited identical symptoms in the field. In the pathogenicity test performed on seven commercial cultivars, the pathogens exhibited strong virulence in both wound and non-wound inoculations. Among the cultivars tested, Arirang-1ho, Arirang-2ho, and Golden Ball were resistant to the pathogens. Furthermore, when testing effective fungicides in vitro, mancozeb and difenoconazole were found to be effective agents for inhibiting mycelial growth. In summary, our findings suggest that A. alternata plays a critical role in leaf disease in potato crop regions and emphasise the necessity for continuous monitoring and management to protect against this disease in South Korea.

Phialemonium inflatum is a useful fungus known for its ability to mineralise lignin during primary metabolism and decompose polycyclic aromatic hydrocarbons (PAHs). However, no functional genetic analysis techniques have been developed yet for this fungus, specifically in terms of transformation. In this study, we applied an Agrobacterium tumefaciens-mediated transformation (ATMT) system to P. inflatum for functional gene analysis. We generated 3,689 transformants using the binary vector pSK1044, which carried either the hygromycin B phosphotransferase (hph) gene or the enhanced green fluorescent protein (eGFP) gene to label the transformants. Southern blot analysis showed that the probability of a single copy of T-DNA insertion was approximately 50% when the co-cultivation time of fungal spores and Agrobacterium tumefaciens cells was performed at 24–36 h, whereas at 48 h, it was approximately 35.5%. Therefore, when performing gene knockout using ATMT, co-cultivation was reduced to ≤ 36 h. The resulting transformants were mitotically stable, and PCR analysis confirmed gene integration into the transformant genome. Additionally, hph and eGFP gene expressions were confirmed by PCR amplification and fluorescence microscopy. This optimised transformation system will enable functional gene analysis to study genes of interest in P. inflatum.

The multifunctional carbon-catabolite repression-negative on TATA box less complex (CCR4-NOT) is a multi-subunit complex present in all eukaryotes, including fungi. This complex plays an essential role in gene expression; however, a functional study of the CCR4-NOT complex in the rice blast fungus Magnaporthe oryzae has not been conducted. Seven genes encoding the putative CCR4-NOT complex were identified in the M. oryzae genome. Among these, a homologous gene, MoNOT3, was overexpressed during appressorium development in a previous study. Deletion of MoNOT3 in M. oryzae resulted in a significant reduction in hyphal growth, conidiation, abnormal septation in conidia, conidial germination, and appressorium formation compared to the wild-type. Transcriptional analyses suggested that the MoNOT3 gene affects conidiation and conidial morphology by regulating COS1 and COM1 in M. oryzae. Furthermore, monot3 exhibited a lack of pathogenicity, both with and without wounding, which is attributable to deficiencies in the development of invasive growth in planta. This result was also observed in onion epidermal cells, which are non-host plants. In addition, the MoNOT3 gene was involved in cell wall stress responses and heat shock. Taken together, these observations suggest that the MoNOT3 gene is required for fungal infection-related cell development and stress responses in M. oryzae.