Induced Mutations for Plant Breeding·Agricultural Biotechnology
LI Jiehua, WANG Qianqian, HE Yuhua, ZHAO Shuang, LIU Ye, ZHANG Fei, CHEN Fadi, FANG Weimin
To explore the optimal in vitro sporulation conditions for the pathogen causing chrysanthemum black spot disease, Alternaria alternata CJ3 was used as the test strain to study the effects of single factors, including temperature, photoperiod, incubation period and ultraviolet irradiation duration on pathogen sporulation. In addition, an orthogonal experiment was designed to establish the optimal inoculation system by investigating the effects of inoculation temperature, inoculation concentration and inoculation method on isolated leaves of the garden chrysanthemum Lingyan Huang. The optimal inoculation system was subsequently verified on living plants. The results showed that the optimal sporulation conditions of CJ3 were irradiating with ultraviolet light for 15 min after mycelial damage and incubating at 22 ℃ in complete darkness for 28 d. When isolated leaves of the garden chrysanthemum were inoculated by rubbing them with spore suppension of 1×108 CFU·mL-1 and placed under 22 ℃, the incidence rate reached 93.33% and the disease index was 80.33, significantly higher than that of other treatments. These suggested that inoculating with spore suspension was the most effective method for identifying resistant to black spot disease in garden chrysanthemum. The incidence rate on the living plants was 90.00%, and the disease index was 71.58. The correlation coefficient between in vitro and in vivo inoculations was 0.83 (P<0.01), indicating this inoculation system was suitable for both in vitro and in vivo identification of disease resistance in garden chrysanthemums. This study optimized the sporulation conditions of the pathogen causing chrysanthemum black spot disease and the disease resistance identification system using spore suspension inoculation, which will provide references and technical support for sporulation induction, disease prevention and control, and disease-resistant breeding.