The process of antagonism of Sclerotium cepivorum in white rot affected onion roots by Trichoderma koningii |
| |
| Authors: | D A Metcalf † C R Wilson |
| |
| Institution: | Tasmanian Institute of Agricultural Research, New Town Research Laboratories, GPO Box 192B, Hobart, Tasmania 7001, Australia;and;Tasmanian Institute of Agricultural Research, University of Tasmania, GPO Box 252-54, Hobart, Tasmania, Australia |
| |
| Abstract: | Trichoderma koningii (strain Tr5) grew in the epidermal mucilage of onion roots without entering healthy epidermal tissue. When placed on the epidermis of Sclerotium cepivorum -infected roots, T. koningii colonized epidermal passage cells, with little colonization of other epidermal tissues, then branched and spread throughout the root cortical tissues damaged by enzymes and toxins which diffused ahead of S. cepivorum hyphae, and impeded the path of the infection. When T. koningii colonized infected tissue, many S. cepivorum hyphae became detached at septa, cell walls dissolved and many hyphal apices burst. Contact between hyphae was not necessary for lysis to occur. T. koningii produced two endochitinases ( R f 0·15 and 0·24) and two exo-acting chitinolytic enzymes ( R f 0·46 and 0·62) during degradation of crabshell chitin and S. cepivorum cell walls. The R f 0·24 and 0·46 proteins were detected when T. koningii colonized S. cepivorum -infected roots and are likely to be a component of the antagonism process. |
| |
| Keywords: | chitinase onions passage cells Sclerotium cepivorum Trichoderma koningii white rot |
|
|
