Correlation between sensitivity to zoxamide and the mutation of β-tubulin amino acid of Colletotrichum gloeosporioides and two Phytophthora spp.isolates

The correlation between mutations of β-tubulin amino acid and the sensitivity of Colletotrichum gloeosporioides,Phytophthora capsici and P.cactorum isolates to carbendazim,diethofencarb and zoxamide was investigated by the methods of the mycelial growth inhibition and amino acid sequence alignment.The results revealed that C.gloeosporioides isolates exhibiting different sensitivity to zoxamide,carbendazim and diethofencarb were associated with the mutations in position 198 or 200 on β-tubulin amino acid sequence.Carbendazim-sensitive isolates of C.gloeosporioides with glutamic acid (E) and phenylalanine (F) at 198 and 200 sites respectively in β-tubulin amino acid sequence were insensitive to diethofencarb and zoxamide.A substitution of tyrosine (Y) for glutamic acid (F) in position 200 was detected in carbendazim-resistant but diethofencarb and zoxamide insensitive isolates.Glutamic acid (E) to alanine (A) change at position 198 was identified in carbendazim high resistant isolates that were sensitive to diethofencarb and zoxamide.All tested P.capsici and P.cactorum isolates were sensitive to zoxamide,but insensitive to carbendazim and diethofencarb.No amino acid sequence difference was detected among all Phytophthora isolates,but the sites from 196 to 200 in β-tubulin amino acid sequence of Phytophthora spp.were significantly different from that of C.gloeosporioides. These might be the reason for the sensitivity of Phytophthora spp.to zoxamide only.