Zhang Yanjun, Zhang Xiao, Qiu Weiliang
Agro-Environmental Protection Institute, Ministry of Agriculture and Rural Affairs, Tianjin, China.
National Pesticide Engineering Research Center, Nankai University, Tianjin, China.
Front Microbiol. 2023 Sep 6;14:1243017. doi: 10.3389/fmicb.2023.1243017. eCollection 2023.
(Zimmermann) Zare & Gams is used as an effective biopesticide for the control of sap-sucking insect pests on agricultural crops. However, low fungicide tolerance limits its large-scale field application. To improve the propamocarb tolerance in , a composite mutagenesis system was established by using UV-light (U), N-Methyl-N'-nitro-N-nitrosoguanidine (NTG) (N) and N ion-beam (I). The permutation type of three agents was a consecutive mutagenesis treatment (I/N/U) after an intermittent treatment (U + N + I). The "U" mutagenesis was performed at 254 nm for 60 s and at a distance of 45 cm under a 20 W germicidal lamp, the "N" mutagenesis was performed at a concentration of 1.0 mg/mL NTG for 60 min, and the "I" mutagenesis was performed by low energy N ion-beam using a dose of 10 × 10 ions/cm at 30 keV. This composite mutagenesis system was recorded as the "U + N + I + I/N/U," and then the mutagenesis efficiency in improving propamocarb tolerance was assessed by analyzing changes of mutants in the propamocarb sensitivity, mitotic stability, mycelial growth speed on plates or in liquid, sporulation on plates or aphids, conidial germination, 50% lethal concentration (LC) and 50% lethal time (LT) to aphids, lipid constituent and cell membrane permeability and control against aphids in the presence or absence of propamocarb. Compared to the wild-type isolate with a 50% effective concentration (EC) value of 503.6 μg/mL propamocarb, the Ll-IC-UNI produced by the "U + N + I + I/N/U" had the highest EC value of 3576.4 μg/mL and a tolerance ratio of 7.1. The mutant was mitotically stable in 20-passage cultivation and did not show any unfavorable changes in growth and virulence indicators. The mutant showed the highest ability to resist or avoid the damaging effects of propamocarb as reflected by the alternations of lipid constituents and membrane permeability. The interval time for applying fungal agent was significantly shortened in this mutant after spraying a field recommended dose of 550 μg/mL propamocarb. In conclude, the "U + N + I + I/N/U" composite mutagenesis mode was efficient and useful to improve the propamocarb-tolerance of and the obtained Ll-IC-UNI could have commercial potential for field application.
（齐默尔曼）Zare & Gams被用作一种有效的生物杀虫剂，用于防治农作物上的刺吸式害虫。然而，其对杀菌剂的耐受性较低，限制了其大规模田间应用。为提高对霜霉威的耐受性，通过使用紫外线（U）、N-甲基-N'-硝基-N-亚硝基胍（NTG）（N）和氮离子束（I）建立了复合诱变系统。三种诱变剂的排列方式是在间歇处理（U + N + I）后进行连续诱变处理（I/N/U）。“U”诱变在254 nm下，于20 W杀菌灯下距离45 cm处进行60 s；“N”诱变在浓度为1.0 mg/mL的NTG中进行60 min；“I”诱变通过低能氮离子束在30 keV下以剂量10×10离子/cm²进行。这种复合诱变系统记录为“U + N + I + I/N/U”，然后通过分析突变体在霜霉威敏感性、有丝分裂稳定性、平板或液体中的菌丝生长速度、平板或蚜虫上的产孢量、分生孢子萌发、对蚜虫的50%致死浓度（LC）和50%致死时间（LT）、脂质成分和细胞膜通透性以及在有或无霜霉威存在下对蚜虫的防治效果等方面的变化，评估提高霜霉威耐受性的诱变效率。与野生型菌株相比，野生型菌株对霜霉威的50%有效浓度（EC）值为503.6 μg/mL，“U + N + I + I/N/U”产生的Ll-IC-UNI的最高EC值为3,576.4 μg/mL，耐受性比率为7.1。该突变体在20代培养中有丝分裂稳定，在生长和毒力指标上未显示任何不利变化。突变体通过脂质成分和膜通透性的改变，表现出抵抗或避免霜霉威破坏作用的最高能力。在喷洒田间推荐剂量550 μg/mL的霜霉威后，该突变体施用真菌制剂的间隔时间显著缩短。总之，“U + N + I + I/N/U”复合诱变模式对提高Zare & Gams对霜霉威的耐受性是有效且有用的，获得的Ll-IC-UNI在田间应用方面具有商业潜力。
