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Biological Control
56, No. 3, 2011; Pages: 209 - 216

A screening strategy of fungal biocontrol agents towards Verticillium wilt of cotton

Y. Zheng, Q.-Y. Xue, L.-L. Xu, Q. Xu, S. Lu, C. Gu, J.-H. Guo

Department of Plant Pathology, College of Plant Protection, Nanjing Agricultural University, Engineering Center of Bioresource Pesticide in Jiangsu Province, Key Laboratory of Monitoring and Management of Crop Diseases and Pest Insects, Ministry of Agriculture, Nanjing 210095, China.


Three hundred and seventy-three fungal isolates were obtained from the endorhiza, rhizosphere, and bulk soil of field-grown cotton plants. One hundred and five of them produced obvious inhibition zones against Verticillium dahliae Kleb., so they were selected as antagonists towards this pathogen. An assessment system was established to evaluate these 105 antagonists for their biocontrol potential and plant growth-promoting potential. Their biocontrol potential was assessed according to their in vitro antagonistic activity against V.dahliae and activities of fungal cell wall degrading enzymes including protease, cellulase, and chitinase. Their plant growth-promoting potential was assessed according to their in vitro activities of solubilizing phosphate and fixing nitrogen. Thirty-three antagonists received at least three points of the total value of assessed biocontrol potential and plant growth-promoting potential and were tested for their biocontrol efficacy and growth-promoting effect on cotton under greenhouse conditions. Twelve of them achieved positive biocontrol efficacy ranging from 8.58% to 69.78%; the conventional correlation coefficient of the biocontrol efficacy of these antagonists with their assessed biocontrol potential was 0.926. By using the screening strategy developed in this study, Fusarium oxysporum strain By125, Nectria haematococca Bx247, and Phomopsis sp. By231 were identified as potential BCAs for controlling Verticillium wilt in cotton, for they achieved biocontrol efficacy of 63.63–69.78% towards this disease and increased biomass by 18.54–62.63% under greenhouse conditions. The present study also demonstrated that the endorhiza of field-grown cotton plants may be a richer source of potential BCAs against Verticillium wilt than the rhizosphere and bulk soil.

Graphical abstract

(A) Coincident relationship between the assessed biocontrol potential of 12 antagonists and their biocontrol efficacy in greenhouse. (the correlation coefficient is 0.926); (B) relationship between the assessed in vitro antagonistic activity against Verticillium dahliae of 12 antagonists and their biocontrol efficacy (the correlation coefficient is 0.512); (C) relationship between the assessed cell wall degrading enzyme activities of 12 antagonists and their biocontrol efficacy (the correlation coefficient is 0.388).


Keywords: Verticillium wilt; Cotton; Antagonist; Biocontrol; Screening strategy; Assessment



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