Modulation of conidia production and expression of the gene bbrgs1 from Beauveria bassiana by oxygen pulses and light

•Light and oxygen affected the conidiation in two strains of Beauveria bassiana.•The expression of bbrgs1 was higher in a mutant relative to a wild type strain.•The expression of bbrgs1 was proportional with conidiation yields between strains.•Pathogenicity parameters improved in conidia from culture under oxidant pulses.

Light and oxidant states affect the conidiation in diverse fungi, although the response has not been described when both stimuli are applied simultaneously. Conidial production and quality in Beauveria bassiana were analysed under four conditions for a wild-type (wt) strain and a previously isolated mutant (mt): normal atmosphere (21% O2; NA) or oxygen-enriched pulses (26% O2; OEP), with either light (L) or darkness (D). The response was complemented by following the expression of the bbrgs1 gene, encoding a regulator of the G-protein signal associated to conidia production. Conidiation was not significantly affected in the mutant strain by any condition (highest value with NA-L: 2.7 × 108 con cm−2). Relative to maximal levels under NA (NA-D: 4 × 107 con cm2), the wt strain diminished conidiation by 34-fold under OEP. The expression of bbrgs1 was higher (up to 188 times) in the mutant strain in every condition relative to the wt strain, in fact expression levels were consistent with the conidiation yields between strains. Viability and hydrophobicity were less affected by culture conditions, although pathogenicity parameters improved in conidia from OEP. The response to OEP, either with light or darkness, was strain-dependent for conidial production, viability, hydrophobicity and infectivity of conidia, then these parameters could be modulated in mass production processes.

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