Pseudocryphonectria elaeocarpicola gen. et sp. nov. (Cryphonectriaceae, Diaporthales) causing stem blight of Elaeocarpus spp. in China

Abstract

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.