Trichoderma harzianum as inductor of a biochemical defense responses against Septoria tritici

Y. MANSILLA; C. SEGARRA; C. CORDO; M. STOCCO; G. LAMPUGNA; C. ABRAMOFF; N. KRIPELZ; N. ALONSO; E.PAREDES; F. NAVARRETE; G. AVENTIN; C. MÓNACO

Mexico

Congreso; 8th International Symposium on Mycosphaerella and Stagonospora Diseases of Cereals; 2011

International Maize and Wheat Improvement Center

The use of antagonists, single or combined with fungicides, is proposed an important tool forthe leaf blotch of wheat management. The purpose of this study was to demonstrate theinduction of a biochemical response when T. harzianum strains actived an antifungal actionagainst Septoria tritici of wheat at three growth stages The experiment was conducted in anexperimental field during 2009 and 2010. A block design with 18 treatments and 3 replicationswas used. The treatments were: 2 strains of T. harzianum (Th5cc and Th118) that were appliedas a seed coating and as a leaf spray at two growth stages (tillering) and (heading); healthycontrol plants(T) without the pathogen and the antagonists and control plants (Ti) inoculatedwith S. tritici. After 21 days of S. tritici inoculation, the extent of the leaf necrosis area and thepycnidial coverage percentage were estimated for each growth stage on Buck 55CL2 wheatcultivar. In addition, the leaf apoplast antifungal proteolytic activity was measured in plants 22days after sowing. The proteolytic activity of the intercellular wheat fluid (IWF) and theendogenous germin-like protease inhibitors (GPI) were demonstrated throughout the growthstages till maturity. The literature shows that the antifungal action decreased in plants thatwere only inoculated with S. tritici but increased in those grown from seeds coated with the T.harzianum (Th5cc) strain. This increase stimulated defenseses to the wheat cultivar. For thepresent experiment the proteolytic activity of the (IWF) decreased on (Ti.) at tillering andheading. The proteolytic activity was similar to the healthy control when plants coming fromcoated seeds were sprayed with T. harzianum in both mentioned stages. The proteolyticactivity was regulated by the GPI activity. At heading, the GPI was almost undetectable in theIWF of the flag leaf. Even so, its inhibitory activity was critical in the regulation of proteases.It is a first time that we have seen that T. harzianum stimulates a biochemical defense responsein plants inoculated with S. tritici in all growth stages.