Identificación de efectores y caracterización de enzimas modificadoras de histonas en Zymoseptoria tritici

Zymoseptoria tritici is one of the most damaging pathogenic wheat fungus, causing crop losses worldwilde. To colonize the host pathogens produce effectors, which are proteins that manipulate the plant immune system. Some effectors, known as avirulance factors, are recognized by plant resistance proteins and induce an immune response that will prevent the development of the infection. Thus, effectors play a central role in plant pathogen interactions. In this work, the function of two putative effectors, Zt09_0_00069 and Zt09_6_00224, identified in a previously performed Genome wide association study (GWAS), was investigated. Disruption of the gene Zt09_0_00069 in a virulent strain of Z. tritici did not result in any virulence differences. In contrast, expression of the avirulent allele of the gene Zt09_6_00224 led to a reduction of infection symptoms in two out of the three independent mutant lines obtained, while the expression of the virulent allele did not show any differences in the infection progress. The results indicates that the effector encoded by Zt09_6_00224 is a possible avirulence factor recognized specifically by the cultivar Tadinia. Epigenetic modifications in histones regulate the expression of fungal effector genes. Histone acetyltransferasas (HATs) plays an important role in gene expression activation by modifying chromatin state. In the present work, three Z. tritici HATs were identified. To determine the function of these HATs, we disrupted the three genes and fitness assays with the obtained knockout mutants were performed. Disruption of SAS2 (Something about silencing 2), a well-known HAT, led to increase accumulation of melanin production and enhance formation of hyphae, indicating that SAS2 is a regulator of melanization and dimorphism. Knockout mutants of the other genes encoding HATs, 3D7.g4775 and 3D7.4263, had slower growth rate than the control strain. The work performed demonstrate that the HATs investigated are involved in the fungal development. Understanding the molecular mechanisms involved in the interaction between plant and fungi, including the characterization of effector genes, as well as their regulatory mechanisms, is key in the fight against septoria tritici blotch. This work has contributed to the identification of a possible avirulence gene and has initiated the characterization of three Z. tritici histone acetyltransferases