Establishment of a resistance-identification method on asparagus stem blight and evaluation of Asparagus officinalis germplasms
Asparagus stem blight is a devastating regional disease and the development of resistant cultivars is the most economical and effective control method. However, there has not been a simple, fast, and effective resistance-identification method. Four inoculation methods were compared on seedlings of 'JK701' and 'TX-4/SD'. The methods were 1) a mycelial pellet colonized by the pathogen was placed the base of stems, 2) inoculation at the middle of stems, 3) inoculation at the stem bases and the middle of stems, and 4) inoculation using a spore-spraying method. The results revealed that the spore-spraying method was easier for operation, faster in producing disease symptoms and more convenient to rate disease categories. The other three methods only produced slight symptoms. The spore-spraying method was then optimized further, by screening for more virulent isolates and adjusting inoculum concentrations. The results showed that the isolate FJ2 displayed the strongest virulence and was chosen for future assays and that 1×106 spore mL‑1 was the optimal concentration. To verify the accuracy of the spore-spraying method, five cultivars with different resistance levels were tested both at the one-month asparagus seedling and the one-year adult phase and the identification results of the seedling phase were closely aligned with adult plants. Finally, 31 asparagus lines including a wild asparagus accession were screened for resistance using the established spore-spraying method. The results revealed, that the wild asparagus was immune, whereas the disease indexes of 'TX-4/SD', 'Shuofeng' and 'UC157' were low, and were therefore identified as highly resistant germplasm resources, while others were susceptible.
Yang, Ying-Qing, Sun, Qiang, Li, Chuan-Ming, Chen, Hong-Fan, Zhao, Feng, Huang, Jian-Hua, Li, Xiang-Min and Lan, Bo (2020). Establishment of a resistance-identification method on asparagus stem blight and evaluation of Asparagus officinalis germplasms. Acta Hortic. 1301, 193-198
asparagus stem blight, resistance-identification method, establishment, resistant germplasm resource, screening