禾谷镰孢菌对氰烯菌酯的敏感性基线及室内抗药性风险初步评估

 本文报道了禾谷镰孢菌(Fusarium graminearum)对氰烯菌酯(2-氰基-3-氨基-3-苯基丙烯酸乙酯,JS399-19)的敏感性基线及其抗药性风险。离体条件下氰烯菌酯对51个禾谷镰孢菌菌株的平均EC₅₀和MIC值分别为(0.153±0.050)μg/mL和小于4.0μg/mL;通过紫外线照射和药剂驯化的方法获得了14个禾谷镰孢菌对氰烯菌酯的抗药性突变体,紫外光诱变抗药性突变频率为1.67×10^-7。这些突变体的抗性水平可分为低、中、高3种类型,其EC₅₀分别为1.5~15.0μg/mL、15.1~75.0μg/mL和75.0μg/mL以上。与亲本菌株2021相比,抗药突变体间的菌丝生长量和产生子囊壳能力发生不同程度的增加或下降,而分生孢子繁殖量则显著下降。在无药培养基上菌丝体转代培养8次后,抗药水平保持不变,且与亲本菌株有相同的致病性。所测定的突变体在含1%葡萄糖的PDA上菌丝生长除UV-2021-4显著下降外,其余都表现生长速率比亲本显著增加。在含3%和4%葡萄糖的PDA上2021生长优于亲本菌株。氰烯菌酯与苯并咪唑类、麦角甾醇生物合成抑制剂类、甲氧基丙烯酸酯类、二硫代氨基甲酸盐类和取代芳烃类杀菌剂没有交互抗性。

Study on baseline-sensitivity of Fusarium graminearum to JS399-19 and assessment of the risk of resistance in vitro

This paper presented the baseline-sensitivity of F. graminearum to fungicide JS399-19 (2-cyano-3-amino-3-phenylacrylic acetate) and assessment of the risk of JS399-19. The mean of EC₅₀ and MIC values of JS399-19 inhibiting mycelia growth of 51 wild type isolates were (0.153±0.050) μg/mL and less than 4.0 μg/mL,respectively. In laboratory, we obtained total fourteen resistant mutants derived from wild-type isolate 2021 through ultra-violet (UV) irradiating or fungicide training methods with a frequency of 1.67×10^-7 for UV. These mutants could be divided into three resistance phenotypes of low level resistance (LR), moderate level resistance (MR) and high level resistance (HR), of which determined by the EC₅₀ values 1.5-15.0 μg/mL, 15.1-75.0 μg/mL and more than 75.0 μg/mL, respectively. Resistance of F. graminearum to JS399-19 was stable during the period of 8 subcultures. As compared with their parent isolate 2021, mutants increased or decreased their mycelia growth rate on PDA plate, mycelia dry weight and sexual reproduction ability. However, the conidia production obviously reduced and their pathogenicity did not appear changeable. The growth of mutants were more quickly than their parent, except UV-2021-4 grew slowly, in the media with low osmotic pressure. While, all mutants were much more favourable in growth at moderate and high osmotic pressure. The result also indicated that there was no cross-resistance between JS399-19 and well-known fungicides, such as benzimidazoles, ergosterol biosynthesis inhibitors, strobilurins, dithiodicarbamates and aromatic hydrocarbons.