Pestic Biochem Physiol. 2026 Mar;218:106958. doi: 10.1016/j.pestbp.2026.106958. Epub 2026 Jan 14.
ABSTRACT
The insect biocontrol fungi (IBF) 'hidden' within the dead insect bodies come out of the insect cadavers for dissemination until the suitable environment conditions arising. However, details of the IBF balancing fungal cells 'hidden' within the cadavers and penetration of the cuticle outwards for growth remain limited. Here, a HsbA domain-containing protein, BbHsbA, was found to express during the later stages of insect colonization in an IBF, Beauveria bassiana, which distributed in cytoplasm and cell wall. BbHsbA disruption did not significantly affect fungal virulence, while the mutant penetrated the cuticle from the inside-out for growth on the cadaver surface rapidly as compared to the wild type strain, accompanying with elevated lipid droplet (LD) levels. Conversely, BbHsbA overexpression significantly decreased LD content while increased cell wall chitin and glycoprotein levels, resulting in reduced virulence and delayed cuticle penetration outwards from the cadavers. Furthermore, BbHsbA was found to interact with the LD membrane protein perilipin and the peroxisome protein peroxin 14, balancing lipid synthesis and storage while also contributing to cell wall homeostasis as a cell wall component within the insect cadavers. The distinct traits between the gene disruption and overexpression strains were in line with the altered expression patterns of lipid metabolism, chitin hydrolysis and other cell wall biosynthesis-associated genes. These results demonstrate that B. bassiana expresses BbHsbA during the later stages of insect colonization to postpone the rapid cuticle penetration outwards from the dead insect bodies via orchestrating lipid metabolism and cell wall-synthesis homeostasis within the cadavers.
PMID:41629026 | DOI:10.1016/j.pestbp.2026.106958