Metarhizium Infection

The Metarhizium genus consists of cosmopolitan fungi that infect a wide range of arthropod hosts. The infection is a complex process enclosing several steps, typically culminating in host death. During infection, Metarhizium spp. form different infection-specialized cellular structures and secrete a set of hydrolytic enzymes that helps to breach the chitin-rich host cuticle and to access the host hemolymph. Amongst these secreted enzymes there are chitinases. These enzymes catalyze the hydrolysis of β-1,4 glycosidic bonds between GlcNAc monomers in chitin. In fungi, chitinases display not only nutritional importance, but also exhibit morphogenic and autolytic functions, acting on different processes of fungal development and life cycle maintenance.

A genomic analysis performed in our laboratory, in M. anisopliae E6 strain, identified twenty-four putative genes containing the GH18 domain, which were classified five subgroups. Nine genes were assigned to subgroup A, seven genes to B, four to C, one gene to D and three genes to a subgroup containing only ENGases. The importance of the horizontal acquired gene from subgroup D (chimaD1) remains unknown in M. anisopliae. The present study aims to evaluate, through the construction of knockout mutants, the function of this gene in the fungus life cycle, as well as exploit the distribution, conservation and gene phylogeny in filamentous fungi. The chimaD1-disrupted strain and a complemented strain have been constructed. These strains do not have any hyphal alteration, as well as alterations in sensibility to stressors agents (CaCl2, Calcofluor White, Congo Red, H2O2, KCl, NaCl) or susceptibility to mycoparasitic fungi Trichoderma atroviride. The phylogenetic analysis lead us to suppose a putative function related to host infection, in view of the narrow gene distribution, only present amongst mycoparasitic and entomopathogenic