Symbiotic and toxinogenic spp. isolated from soils of different papaya producing regions in Mexico.

Mucoralean fungi from the genus are common inhabitants of terrestrial ecosystems, being some pathogens of animals and plants. In this study, we analyzed the symbiotic and toxinogenic potential of species derived from agricultural soils dedicated to the production of papaya ( L.) in Mexico. Four representative strains of soil-derived spp. were analyzed employing molecular, microscopic, and metabolic methods. The ITS phylogenies identified the fungi as HP499, HP475 and HP479, and HP487. We discovered that HP499 and HP475 harbor similar endofungal bacterial symbionts that belong to the genus ( sensu lato) and that none of the four fungi were associated with RmNV-20S and RmNV-23S. Intriguingly, the interaction between - showed different phenotypes from known - symbioses. Elimination of bacteria in HP475 did not cause a detrimental effect on fungal growth or asexual reproduction. Moreover, metabolic and molecular analyses confirmed that, unlike symbiotic HP499, HP475 does not produce rhizoxin, one of the best-characterized toxins produced by spp. The rhizoxin () biosynthetic gene cluster seems absent in this symbiotic bacterium. Our study highlights that the symbioses between and are more diverse than anticipated. Our findings contribute to expanding our understanding of the role bacterial symbionts have in the pathogenicity, biology and evolution of Mucorales.