Horizontal transfer of a subtilisin gene from plants into an ancestor of the plant pathogenic fungal genus Colletotrichum

ARMIJOS-JARAMILLO V D; VARGAS W A; SUKNO S A; THON M R

PLOS ONE

PUBLIC LIBRARY SCIENCE

Lugar: San Francisco; Año: 2013 vol. 8

1932-6203

The genus Colletotrichum contains a large number of phytopathogenic fungi that produce enormous economiclosses around the world. The effect of horizontal gene transfer (HGT) has notbeen studied yet in these organisms. Inter-Kingdom HGT into fungal genomes hasbeen reported in the past but knowledge about the HGT between plants and fungiis particularly limited. We describe a gene in the genome of several species ofthe genus Colletotrichum with astrong resemblance to subtilisins typically found in plant genomes. Subtilisinsare an important group of serine proteases, widely distributed in all of thekingdoms of life. Our hypothesis is that the gene was acquired by Colletotrichum spp. through (HGT) fromplants to a Colletotrichum ancestor.We provide evidence to support this hypothesis in the form of phylogeneticanalyses as well as a characterization of the similarity of the subtilisin atthe primary, secondary and tertiary structural levels. The remarkable level ofstructural conservation of Colletotrichumplant-like subtilisin (CPLS) with plant subtilisins and the differences withthe rest of Colletotrichum subtilisins suggests the possibility of molecularmimicry. Our phylogenetic analysis indicates that the HGT event would haveoccurred approximately 150?155 million years ago, after the divergence of the Colletotrichum lineage from other fungi.Gene expression analysis shows that the gene is modulated during the infectionof maize by C. graminicola suggestingthat it has a role in plant disease. Furthermore, the upregulation of the CPLScoincides with the downregulation of several plant genes encoding subtilisins.Based on the known roles of subtilisins in plant pathogenic fungi and the geneexpression pattern that we observed, we postulate that the CPLSs have animportant role in plant infection.