Characterization of Two Fungal Isolates from Cotton and Evaluation of their Potential for Biocontrol of Verticillium Wilt of Cotton

Two isolates ( CV d‐ WH w and CV n‐ WH g) recovered from Verticillium‐wilt‐symptomatic cotton grown in H ubei P rovince of C hina were identified based on their morphology, growth characteristics in culture, specific amplification and identification of internal transcribed spacer ( ITS ) r DNA sequence. According to the morphological characteristics, specific PCR amplification and ITS sequences, CV d‐ WH w was identified as V . dahliae and CV n‐ WH g as G ibellulopsis nigrescens . In bioassays, the two isolates had significantly lower pathogenicity to cotton plant than V . dahliae isolate CV d‐ AY b. Cotton pre‐inoculated with isolate CV n‐ WH g or CV d‐ WH w exhibited reduced disease indices of V erticillium wilt compared with those inoculated with CV d‐ AY b alone. Cotton co‐inoculated with CV n‐ WH g or CV d‐ WH w and CV d‐ AY b provided increased protection from subsequent CV d‐ AY b inoculation. These results suggest that the two isolates have the potential to be developed as biocontrol agents for the control of V erticillium wilt in cotton. To our knowledge, this is the first report of a cross‐protection phenomenon using G ibellulopsis nigrescens against V erticillium wilt caused by V . dahliae on cotton.