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Acta Horticulturae Sinica ›› 2024, Vol. 51 ›› Issue (8): 1906-1912.doi: 10.16420/j.issn.0513-353x.2023-0494

• Plant Protection • Previous Articles     Next Articles

Resistance of Colletotrichum gloeosporioides Species Complexes from Grape to Azoxystrobin

YANG Jinghui1, XU Yuan1, XIAO Ting1, CHU Shupin2, LIU Jixiang1, YAO Kebing1,*()   

  1. 1 Zhenjiang Institute of Agricultural Sciences in Hilly Area of Jiangsu Province,Jurong,Jiangsu 212400,China
    2 Jiangsu Plant Protection and Quarantine Station,Nanjing 210036,China
  • Received:2024-02-06 Revised:2024-06-19 Online:2024-08-25 Published:2024-08-22
  • Contact: YAO Kebing

Abstract:

The sensitivity and resistance molecular mechanism of Colletotrichum gloeosporioides species complexes(CGSC)derived from the hilly area of Jiangsu Province to azoxystrobin were studied. Employing the methods of spore germination and discriminative dose(a concentration that fully inhibits mycelial growth of the sensitive strains),the effective inhibition medium concentration values(inhibits mycelia growth by 50% relative to the control,EC50)to azoxystrobin and sensitivity types of 51 single spore isolates of CGSC(C. aenigmaC. viniferum and C. fructicola)were identified. The field control efficacy test inoculated with conidia suspension of sensitive,resistant and mixed strains(the resistant strain and sensitive strain with the same conidia concentration were mixed in equal volume)was used to evaluate the epidemic of fungicides resistance of CGSC. Furthermore,the molecular mechanisms of azoxystrobin were determined by the sequence analysis of the target gene(mitochondrial cytochrome b,CYTB). Among the 27 strains of C. aenigma and 16 strains of C. viniferum,20 and 14 strains were sensitive to axoxystrobin,with EC50 values of 0.0388(0.0150-0.0770)and 0.0614(0.0213-0.0906)mg · L-1,respectively,while the EC50 values of resistant strains were greater than 100 mg · L-1. All the C. fructicola strains were resistant and their EC50 values were greater than 100 mg · L-1. Field inoculated test of azoxystrobin at twice recommended field dose(250 mg · L-1)against resistant strains have lost the control efficacy(control efficacy 7.11%). Sequence analysis of target gene(CYTB)showed that all resistant strains harbored G143A(Glycine substituted by Alanine)point mutation in CYTB. The CYTB can be divided into two types based on whether there are partial deletions in the sequence of the intro adjoining after the G143 amino acid position. The sensitivity of different species in CGSC to azoxystrobin exhibits heterogeneity. The prevalence of resistant populations was the main factor leading to a decrease in field control effectiveness. The genotype of resistance to azoxystrobin of CGSC belonged to the point mutation of single base of target gene,which resulted in the substitution of amino acids,i.e. G143A,and no other genotypes of point mutations were found in this research.

Key words: grape, grapevine anthracnose, Colletotrichum gloeosporioides species complexes, azoxystrobin, resistance, molecular mechanism