Unveiling Species Diversity of Plectosphaerellaceae (Sordariomycetes) Fungi Involved in Rhizome and Root Rots of Ginger in Shandong Province, China

Ginger holds significant economic importance in both China and worldwide agriculture. Fungi from the family <i>Plectosphaerellaceae</i> are globally recognized as aggressive plant pathogens. However, the effects of <i>Plectosphaerellaceae</i> species on ginger have been poorly understood. In this research, we identified two novel <i>Musidium</i> species (<i>M. shandongensis</i> sp. nov. and <i>M. zingiberis</i> sp. nov.), one newly recorded species (<i>Gibellulopsis serrae</i>) and one new host record (<i>Plectosphaerella cucumerina</i>) from the rotten rhizomes and roots of ginger in Shandong Province, China, utilizing morphological observations combined with multilocus phylogenetic analysis of the 28S large subunit (LSU), internal transcribed spacer (ITS) region, and translation elongation factor 1-alpha (<i>TEF1</i>-<i>α</i>) gene, along with pathogenicity analyses. Key diagnostic features include <i>M. shandongensis</i> exhibiting abundant mycelium ropes and coils, <i>M. zingiberis</i> showing dark olivaceous colonies, <i>G. serrae</i> producing brown chlamydospores, and <i>P. cucumerina</i> displaying conspicuous guttulae conidia. Comparative analyses with closely related taxa were based on detailed morphological descriptions, illustrations, and phylogenetic analyses. Artificial inoculation of healthy ginger in vitro and in vivo assays caused characteristic symptoms, such as wilt, leaf yellowing, and rhizome necrosis, identical to those observed on naturally infected plants. Our findings broaden current knowledge on the diversity of <i>Plectosphaerellaceae</i> associated with ginger, revealing them as serious threats to ginger cultivation in China.