QTL for resistance to Trichoderma lytic enzymes and metabolites in Agaricus bisporus

Abstract

National audienceTrichoderma aggressivum leads to severe crop losses in Agaricus bisporus cultures. The development of strain resistant to this competitor is an alternative to the use of chemicals. One of the interacting components of the putative system of resistance is the lack of susceptibility to the growth limiting compounds produced by Trichoderma sp. Wide variation for this trait has been previously demonstrated, with few strains able to resist to Trichoderma lytic enzymes and metabolites. For exploiting such a resistance in breeding programs, the knowledge of its genetic basis is a prerequisite. Therefore, QTL analysis was used to determine the number, effects and location of genomic regions associated with tolerance to Trichoderma lytic enzymes and metabolites in a hybrid progeny of A. bisporus. An in vitro experiment using sequential cultures on media supplemented or not with a commercial product Lysing Enzyme was used. The mycelium growth rate in control condition, the level of tolerance and the capacity of adaptation were the traits used for QTL detection. In total for all the traits, seven QTLs were detected distributed on four genomic regions. Two clusters of QTLs related to several traits and two other trait-specific QTLs were identified. A genomic region on LGIV was detected for each trait, with the highest LOD score value and genetic effects. Our results showed that tolerance to Trichoderma lytic enzymes and metabolites was tightly related to mycelium growth ability. Consequences for mushroom breeding program are discussed