宜宾烟区烤烟野火病的致病力分化、生物学特性及抑菌药剂筛选

Pathogenicity differentiation and biological characteristics of Pseudomonas syringae pv.tabaci and effective bactericide screening in Yibin tobacco planting areas

为了更有效地防治烟草野火病,对采自宜宾市烤烟种植区的具有典型野火病症状的烟叶样品进行了组织分离、培养和形态特征观察。采用针刺结合无针头注射接种法测定分离菌株的致病性,同时采用病菌生长速率法测定了不同致病力的菌株pv-xs-y-2(强)、pv-xt-y-2(中)和pv-gy-y-1(弱)的生物学特性及4种杀菌剂对强致病力菌株pv-xs-y-2的室内抑制效果。结果表明:14个菌株的形态特征均与烟草野火病病菌的形态特征一致,但各菌株间的致病力有明显的差异,平均病情指数为23.33~72.22。聚类分析结果显示,14个菌株在鉴别寄主(K326)上的致病力划分为强(病指为60~72.22)、中(病指为34.44~53.33)和弱(病指为23.33)3种类型,其中以中等致病力类型的菌株为主,占测试菌株的71.43%。在人工培养条件下,病菌的最适生长温度为28℃,pv-xs-y-2、pv-xt-y-2和pv-gy-y-1菌株的OD_(600)值分别为1.285、1.105和0.977;最适生长湿度为100%,pv-xs-y-2、pv-xt-y-2和pv-gy-y-1的OD_(600)值分别为0.694、0.555和0.505;最适pH值为7,说明野火病菌适宜在中性环境中生长。不同药剂对野火病室内毒力的测定结果依次为3%噻霉酮>4%春雷霉素>72%硫酸链霉素>20%噻菌铜,3%噻霉酮的有效中浓度(EC_(50))为9.401μg·mL^(-1)。

To control Pseudomonas syringae pv.tabaci more effectively, pathogen was isolated from the tobacco leaves with typical wildfire symptom in Yibin tobacco planting areas. The isolated pathogen was cultured to observe its morphological characteristics. The pathogenicity of pathogen strains was evaluated via acupuncture inoculation and injection inoculation without needle. The biological characteristics of representative strains[pv-xs-y-2（strong）, pv-xt-y-2（moderate） and pv-gy-y-1（weak）] with different pathogenicity were determined by measuring bacteria growth rate, and the inhibition effects of four bactericides on strong pathogenicity strain pv-xs-y-2 were investigated. The results showed that the morphological characteristics of fourteen strains were consistent with those of P. syringae pv. tabaci, but the pathogenicity was significantly different between strains with the average disease index in the range of 23.33-72.22. Based on the pathogenicity of K326, the fourteen strains were clustered into three groups： strong（disease index 60-72.22）, moderate（disease index34.44-53.33） and weak（disease index 23.33）; in which, the strains with moderate pathogenicity accounted for 71.43%. On NA medium, the optimum growth temperature for pathogen was 28 ℃, at which the OD600 values of pv-xs-y-2, pv-xt-y-2 and pv-gy-y-1 were 1.285, 1.105 and 0.977, respectively; the optimum growth relative humidity was 100%, at which their OD600 values were 0.694, 0.555 and 0.505,respectively; the optimum growth pH was 7. The data indicated that neutral environment was suitable for the growth of P. syringae pv. tabaci. The inhibition effects of different bactericides on P. syringae pv.tabaci were 3% benziothiazolinone4% kasugamycin〉72% streptomycin〉20% thiediazole copper, and EC50 value of 3% benziothiazolinone was 9.401 μg·mL-1.