Cryphonectriaceae is a diaporthalean family containing important plant pathogens of which Cryphonectria parasitica is the most notorious one. An emerging stem blight disease on Elaeocarpus apiculatus (Elaeocarpaceae) and E. hainanensis was observed in Guangdong Province of China recently. Typical Cryphonectria blight-like symptoms including cankers on tree barks with obvious orange conidial tendrils were observed. Forty-eight isolates were obtained from diseased tissues and conidiomata formed on the hosts E. apiculatus and E. hainanensis. These isolates were further identified based on both morphology and molecular methods using the combined sequence data of the internal transcribed spacer (ITS) region, large subunit of the nrDNA (LSU), the translation elongation factor 1-alpha (tef1) and DNA-directed RNA polymerase II second largest subunit (rpb2) genes. As a result, the fungus represents an undescribed genus and species within the family Cryphonectriaceae. Hence, Pseudocryphonectria elaeocarpicola gen. et sp. nov. is proposed herein to represent these isolates from diseased barks of E. apiculatus and E. hainanensis. Pseudocryphonectria differs from the other genera of Cryphonectriaceae in having dimorphic conidia. Further inoculation results showed that P. elaeocarpicola is the causal agent of this emerging blight disease in China, which can quickly infect and kill the hosts E. apiculatus and E. hainanensis.

Sirex noctilio and Amylostereum areolatum form a highly specific mutualistic symbiosis. The growth and host-degrading activities of the symbiotic fungus are critical to the woodwasps, which directly influence the larval survival rate and adult body size of the woodwasps. Gene expression analysis has been extensively employed to decrypt the intricate growth patterns of symbiotic fungi and identify the associated functional genes underpinning their degradation pathways. Appropriate reference genes are crucial for enhancing the accuracy of studies on gene expression. In an effort to refine gene expression analysis in A. areolatum, our study cultivated the symbiotic fungi on the wood powder medium of Pinus sylvestris var. mongolica, aligning closer to its natural growth conditions. Thirteen reference genes underwent meticulous evaluation via algorithms such as delta Ct, geNorm, BestKeeper, RefFinder, and NormFinder, depending on their stability amidst diverse growth and developmental epochs of A. areolatum. α-TUB, P450, and the combination (α-TUB + P450) were distinguished as the most stable candidates for RT-qPCR analysis, confirmed through AaLac1 expression validation. These findings contribute significantly to the investigation of gene expression in A. areolatum and facilitate a deeper understanding of its symbiotic relationship with S. noctilio.