Biochemical and molecular characterization of Alternaria alternata isolates highly resistant to procymidone from broccoli and cabbage

Phytopathology Research

Lei Ding¹  Weicheng Zhao²  Bingran Wang²  Pengcheng Zhang²  Tiancheng Lou²  Changjun Chen²  Patrick Sun²  Lingling Wei²  Wenchan Chen²  Kai Wang³  Longbing Huang⁴ 

[1] Agricultural Product Quality Safety Supervision and Management Station of Xiangshui County, 224600, Xiangshui, Jiangsu Province, China;College of Plant Protection, Nanjing Agricultural University, Key Laboratory of Pesticide, 210095, Nanjing, Jiangsu Province, China;Jiangsu Coastal Area Institute of Agricultural Sciences, 224002, Yancheng, Jiangsu Province, China;Plant Protection and Quarantine Station of Xiangshui County

[2] , 224600, Xiangshui, Jiangsu Province, China;

关键词: Alternaria alternata;    Broccoli;    Cabbage;    Resistance;    Dicarboximide fungicides;    Fitness;    AaHK1;   

DOI  :  10.1186/s42483-021-00092-z

来源: Springer

【 摘 要 】

Alternaria alternata, a causal agent of leaf blights and spots on a wide range of hosts, has a high risk of developing resistance to fungicides. Procymidone, a dicarboximide fungicide (DCF), has been widely used in controlling Alternaria leaf blights in China for decades. However, the resistance of A. alternata against DCFs has rarely been reported from crucifer plants. A total of 198 A. alternata isolates were collected from commercial fields of broccoli and cabbage during 2018–2019, and their sensitivities to procymidone were determined. Biochemical and molecular characteristics were subsequently compared between the high-level procymidone-resistant (ProHR) and procymidone-sensitive (ProS) isolates, and also between ProHR isolates from broccoli and cabbage. Compared with ProS isolates, the mycelial growth rate, sporulation capacity and virulence of most ProHR isolates were reduced; ProHR isolates displayed an increased sensitivity to osmotic stresses and a reduced sensitivity to sodium dodecyl sulfate (SDS); all ProHR isolates showed a reduced sensitivity to hydrogen peroxide (H2O2) except for the isolate B102. Correlation analysis revealed a positive cross-resistance between procymidone and iprodione, or fludioxonil. When treated with 10 μg/mL of procymidone, both mycelial intracellular glycerol accumulations (MIGAs) and relative expression of AaHK1 in ProS isolates were higher than those in ProHR isolates. Sequence alignment of AaHK1 from ten ProHR isolates demonstrated that five of them possessed a single-point mutation (P94A, V612L, E708K or Q924STOP), and four isolates had an insertion or a deletion in their coding regions. No significant difference in biochemical characteristics was observed among ProHR isolates from two different hosts, though mutations in AaHK1 of the cabbage-originated ProHR isolates were distinct from those of the broccoli-originated ProHR isolates.

【 授权许可】

CC BY