Study on Rapid Resistance-Identification Method on Asparagus Stem Blight

Objective The objective of this study is to establish a rapid resistance-identification method for asparagus stem blight, providing technical support for disease resistance breeding and the application of resistant varieties.

Method Seven asparagus varieties were assessed for resistance to stem blight using soaking seed and root with mycotoxin, soaking seed with spore suspension, irrigating root with spore suspension, and field natural induction methods, respectively.ResultThe inhibition rate of seed germination on Grande, Jialu No.1, Zaojia No.1, Fengdao No.1, Huamiao, TC, and UC157F₂ was 3.62%, 4.29%, 13.98%, 4.26%, 2.19%, 4.95%, and 15.00%, respectively, after 24 h of soaking seed with mycotoxin. This method showed that the seven tested varieties could be classified into two groups: susceptible and moderately resistant. UC157F₂ and Zaojia No.1 were identified as the susceptible group, and the other varieties as the moderately resistant group. The inhibition rate of root growth on Grande, Jialu No.1, Zaojia No.1, Fengdao No.1, Huamiao, TC, and UC157F₂ was 80.94%, 73.72%, 82.29%, 71.77%, 65.86%, 69.39% and 82.35%, respectively, by soaking root with mycotoxin. The method could divide the seven tested varieties into three groups: susceptible, moderately susceptible and moderately resistant. UC157F₂, Zaojia No.1 and Grande belonged to the susceptible group, Jialu No.1 and Fengdao No.1 to the moderately susceptible group, and TC and Huamiao to the moderately resistant group. The spore suspension of 1.0×10⁵ spores/mL had a strong inhibitory effect on the seed germination, providing the inhibition rate of seed germination on Grande, Jialu No.1, Zaojia No.1, Fengdao No.1, Huamiao, TC, and UC157F₂ being 43.88%, 40.97%, 41.67%, 32.87%, 29.59%, 28.52% and 61.23%, respectively. This method could also divide the seven tested varieties into three groups viz., UC157F₂ as susceptible, Grande, Zaojia No.1 and Jialu No.1 as moderately susceptible, and Fengdao No.1, Huamiao and TC as moderately resistant. When irrigating the root with spore suspension, the incidence rate of all tested varieties was more than 80%, which could not effectively distinguish the disease resistance of tested varieties. Whereas the results of field natural induction method could divide the seven tested varieties into three groups: UC157F₂ belonging to the susceptible group, Zaojia No.1, Grande, Jialu No.1 and Fengdao No.1 as the moderately susceptible group, and Huamiao and TC as the moderately resistant group.

Conclusion The resistance-identification results on asparagus stem blight by soaking seed with spore suspension were significantly correlated with that of field natural induction method (P＜0.01). Therefore, the soaking seed with spore suspension can be combined with field natural induction method to quickly and accurately identify the resistance level to asparagus stem blight.