The ACE Genes in Aphelenchoides Besseyi Isolates and Their Expression Correlation to the Fenamiphos Treatment
Abstract Aphelenchoides besseyi could cause great yield loss on rice and many economically important crops. Acetylcholinesterase inhibitors were commonly used to mitigate plant parasitic nematodes. However, increasing nematicide-resistance has been reported due to the extensive use of these chemicals. The correlation between the AChE-inhibitor (fenamiphos) sensitivities and acetylcholinesterase (ace) genes in two isolates of A. besseyi (designated Rl and HSF) was established. The LD50 of fenamiphos to Rl and HSF were 572.2 ppm and 129.4 ppm, respectively, indicating that two nematode isolates had different sensitivities to fenamiphos. Three ace genes were cloned and sequenced in A. besseyi, and their homology was supported by phylogenic analysis with AChEs protein sequences from various vertebrate and invertebrate species. Molecular docking showed that the affinities of each AChEs to fenamiphos were higher in HSF isolate, indicating that there should be point mutations in Rl isolate AChEs. Treating the two isolates with 100 ppm fenamiphos for 12 h, three ace genes of HSF isolate were down-regulated but were up-regulated in Rl isolate. The results suggest that fenamiphos can transcriptionally modulate the expression of ace genes, as well as the variants in AChEs and increased expression of ace genes might be associated with fenamiphos-insensitivity in Rl isolate.