INIBIOLP   05426
INSTITUTO DE INVESTIGACIONES BIOQUIMICAS DE LA PLATA "PROF. DR. RODOLFO R. BRENNER"
Unidad Ejecutora - UE
congresos y reuniones científicas
Título:
Over-expression of genes may reveal increased tolerance against UV-B radiation in Metarhizium spp. conidia produced on culture medium supplemented with riboflavin (vitamin B2)
Autor/es:
PAIXÃO, F.R.S; ALVES PEREIRA, RONALDO JR.; ROBERTS, DONALD; LUZ, CHRISTIAN; NICOLÁS PEDRINI; CARLA HUARTE BONNET; RANGEL, DRAUZIO; FERNANDES E.K
Reunión:
Congreso; 50th Annual Meeting and Golden Jubilee Celebration of the Society for Invertebrate Pathology; 2017
Resumen:
The success of entomopathogenic fungi is limited by their vulnerability toabiotic stresses, including ultraviolet radiation (UV) in sunlight, viz. UV-A andUV-B, which can significantly reduce the viability and delay germination ofconidia. In an effort to protect conidia from solar irradiation, we evaluatedthe effect of adding riboflavin to culture medium for conidial production onthe tolerance of these conidia to UV-B radiation, as well as the expression ofphotolyase (Phr), laccase (Lcc), and polyketide synthase (Pks) genes inMetarhizium acridum (ARSEF 324) and M. robertsii (ARSEF 2575). Conidia of both isolates were produced on potato dextrose medium without riboflavin(PDA) or PDA supplemented with riboflavin (PDA + Rb) at differentconcentrations and subsequently suspended in Tween 80® or riboflavinsolution. Conidia were also produced on PDA medium supplemented withyeast extract (PDAY), which contains complex B vitamins. The conidia wereexposed to UV-B (3.9, 5.46 or 6.24 kJ.m-2), visible light (16 Klux) for 2 hours,or to UV-B followed by visible light exposure. Relative UV-B tolerance wasdetermined by comparing percent germination of conidia on the variousmedia with and without UV exposure. Conidia from both Metarhiziumisolates produced on PDA + Rb, regardless its concentration, or PDAY wereconsiderably more tolerant to UV-B than conidia produced on PDA mediumwithout supplement. The conidial tolerance of Metarhizium isolates to UV-Bdid not change when conidia were suspended in riboflavin solution,suggesting that these fungi need to produce and accumulate metabolitesinside the conidia to confer photoprotection. The expression of MaLcc3 andMaPks2 for M. acridum, as well as MrPhr2, MrLcc1, MrLcc2, and MrLcc3 forM. robertsii was higher when the isolates were cultivated on PDA + Rb andexposed to UV-B followed by exposure to visible light, or exposed to onlyvisible light, than conidia produced on PDA medium alone. The addition ofriboflavin to substrates used for mass production of Metarhizium spp. andconsequently enhancing the tolerance of conidia against UV-B radiation maybe a viable approach to improving the effectiveness of these fungi inbiological control programs.