Evaluation and identification of anthracnose resistance in pumpkin germplasm

Pumpkin fruits have high nutritional and medicinal values, rendering pumpkin an important economic crop. Anthracnose, caused by pathogenic fungi of the genus Colletotrichum, is one of the major diseases in pumpkin production. It significantly reduces the yield and quality of pumpkin fruits during all plant growth stages. The selection and identification of anthracnose-resistant pumpkin germplasm resources are prerequisites for breeding anthracnose-resistant pumpkins. In this study, based on morphological characteristics and molecular analysis, the Cucurbita species isolated from symptomatic pumpkin fruits was identified as Colletotrichum magnum. The optimal growth conditions for C. magnum in culture were using soluble medium as the carbon source, peptone as the nitrogen source, at a pH of 6, under dark condition at 28 °C. The lethal condition for anthracnose mycelium was exposure to 55 °C for 10 minutes. To effectively identify the resistance of pumpkin germplasm resources, a set of rapid methods for identifying anthracnose resistance was established. This involved spraying a spore suspension of 1×107 conidia/ml at the 2-leaf seedling stage, at a temperature of 25-30 °C and a humidity of 90-100%. A total of 113 pumpkin germplasm resources were evaluated for anthracnose resistance using the established method, and 3 resistant accessions and 19 moderately resistant accessions were obtained. These pumpkin germplasms will be utilized for mapping and identification of anthracnose-resistant genes and for resistance breeding in pumpkins. These results not only provide important materials for anthracnose fungal biology and host resistance mechanisms, but also lay the foundation for the cultivation of pumpkin anthracnose-resistant varieties.