School of Plant Protection, Anhui Agricultural University, Hefei 230036, China.
Key Laboratory of Integrated Crop Pest Management of Anhui Province, School of Plant Protection, Anhui Agricultural University, Hefei 230036, China.
J Agric Food Chem. 2022 Aug 10;70(31):9760-9768. doi: 10.1021/acs.jafc.2c02663. Epub 2022 Jul 28.
Rice bakanae disease (RBD) caused by is a widespread and destructive disease of rice. It is urgent to introduce a new class of fungicide to manage the fungicidal resistance problem and effectively control the disease. Azoxystrobin (AZO) is an active fungicide with a broad antifungal spectrum, while its activity against . is not well investigated. In this study, the baseline sensitivity of . to AZO was established by testing the sensitivity of 100 isolates, collected from Anhui Province of China. The mechanism of resistance to AZO was also investigated. AZO exhibited a strong activity against the 100 . isolates with EC values of 0.822 ± 0.285 and 0.762 ± 0.283 μg/mL for mycelial growth and conidial germination, respectively, and both of the baseline sensitivity curves were validated as unimodal curves. To investigate the resistance mechanism, six mutants with resistance factor (RF) values >50 were generated from wild-type sensitive strains through UV mutagenesis, and sequence analysis showed that mutation G143A in conferred the resistance to AZO. Mycelial growth, conidia production, pathogenicity, and ATP production were decreased in all six resistant mutants as compared to the parental strains, indicating the fitness penalties in this phenotype of resistance mutation. In addition, the cross-resistance assay showed that there was no cross-resistance between AZO and carbendazim, prochloraz, phenamacril, or pydiflumetofen. AZO can be an efficient candidate to control RBD in China with moderate to low fungal resistance risk, but continuous resistance monitoring should be performed during the application of this fungicide.
稻曲病（RBD）由 引起，是一种广泛而具破坏性的水稻病害。引入新的杀菌剂类别来管理杀菌剂抗性问题并有效控制该病害迫在眉睫。唑菌酯（AZO）是一种具有广谱抗真菌活性的农药，但其对 的活性尚未得到充分研究。在本研究中，通过测试从中国安徽省采集的 100 个分离株的敏感性，确定了 的基线敏感性。还研究了对 AZO 产生抗性的机制。AZO 对 100 个 分离株表现出很强的活性，其菌丝生长和分生孢子萌发的 EC 值分别为 0.822 ± 0.285 和 0.762 ± 0.283 μg/mL，并且这两个基线敏感性曲线均被验证为单峰曲线。为了研究抗性机制，通过紫外线诱变从野生型敏感菌株中产生了 6 个 RF 值 >50 的抗性突变体，序列分析表明， 中的 G143A 突变赋予了对 AZO 的抗性。与亲本菌株相比，所有 6 个抗性突变体的菌丝生长、分生孢子产生、致病性和 ATP 产生均降低，表明这种抗性突变体表型存在适应性代价。此外，交叉抗性测定表明，AZO 与多菌灵、丙环唑、苯醚甲环唑或吡氟酰草胺之间没有交叉抗性。AZO 可以成为一种在中国控制 RBD 的有效候选药剂，具有中低真菌抗性风险，但在使用该杀菌剂时应持续进行抗性监测。
