Fungal enemies isolated from the root and rhizosphere of guava against the root-knot nematode

ABSTRACT

The fungal microbiota associated with the roots and rhizosphere of plants represents a significant source of biocontrol agents against the root-knot nematode Meloidogyne spp. While some fungal genera have been studied extensively, others require more attention in terms of their identity and mechanisms of action against plant parasitic nematodes. Thus, the aim of this research was to demonstrate the in vitro and in vivo biocontrol potential of fungi isolated from the root and rhizosphere of guava plants against the root-knot nematode Meloidogyne incognita. We isolated four fungi (C5, C6, C7, and C10) from the root and rhizosphere of guava plants using the serial dilution method. These fungi were purified on potato dextrose agar and evaluated in vitro to assess their ability to parasitize M. incognita eggs and juveniles. Subsequently, the fungi were assessed for M. incognita control under nursery conditions in guava plants. The identity of the fungi with parasitic capacity and biocontrol potential was confirmed by amplifying and sequencing the ITS region, followed by Bayesian inference analysis. Results showed that the fungi corresponded to Talaromyces sayulitensis (C5), Myrothecium sp. (C6), Penicillium shearii (C7), and Beauveria bassiana (C10). Parasitism of M. incognita eggs was confirmed for all fungi, parasitism of juveniles occurred with T. sayulitensis (C5) and B. bassiana (C10). In guava seedlings treated with fungal isolates, a significant reduction in the number of eggs, juveniles, and nodules per gram of root was achieved. The biocontrol potential against M. incognita in guava seedlings was confirmed for different fungi associated with the root rhizosphere.

Key words
eggs; fungi; juveniles; nematode; parasitism