NADH: flavin oxidoreductase/NADH oxidase and ROS regulate microsclerotium development in Nomuraea rileyi

Abstract

Based on transcriptome library, an NADH: flavinoxidore ductase/NADH oxidase gene (Nox) was cloned from Nomuraea rileyi. The 1,663-bp full-length cDNA contains an open reading frame of 1,233 bp coding 410 amino acids. The expression level of Nox was up-regulated and co-related to the intracellular H2O2 concentration during microsclerotium (MS) initiation. Rotenone inhibition showed that inhibition of Nox could cause a noticeable decrease in the MS yields. Silencing of Nox resulted in the MS yields, H2O2 and virulence decreased by 98.5, 38 and 21.5%, respectively. On the other hand, MS yields increased by 24.8-61% when induced by H2O2 or menadione. Furthermore, the reactive oxygen species (ROS) scavenger, ascorbic acid (up to 0.03 g ascorbic acid l(-1)), completely inhibited the formation of MS. In conclusion, the results obtained suggested that ROS promoted MS development, and that Nox was required for MS differentiation through regulation of intracellular H2O2 concentration. Besides, Nox had a great impact on the virulence in N. rileyi.

Statistical optimisation of process variables and large-scale production of Metarhizium rileyi (Ascomycetes: Hypocreales) microsclerotia in submerged fermentation

“…The M. rileyi strain, CQNr01, was obtained from the Chongqing Engineering Research Center for Fungal Insecticides, Chongqing, China. The strain had been used to study the optimisation of culture medium for MS production (Yin et al 2012;Song et al 2014a) and study the molecular mechanism of MS development in our earlier research (Song et al 2013(Song et al , 2016aJiang et al 2014;Liu et al 2014;Zhou et al 2015). The strain was cultured on Sabouraud's maltose agar fortified with 1% yeast extract (SMAY) under continuous light at 25°C.…”

“…For the development of efficient fermentation, the culture conditions and liquid culture fermentation process should be optimised owing to their impact on the M. rileyi MS yields. Optimisation studies could also help in understanding the interactions among the parameters as well as the mechanism of MS development (Song et al 2013(Song et al , 2016aJiang et al 2014;Liu et al 2014;Zhou et al 2015).…”

The high osmotic response and cell wall integrity pathways cooperate to regulate morphology, microsclerotia development, and virulence in Metarhizium rileyi

“…To enhance the fermentation efficiency, we investigated the molecular mechanism of MS formation and found that internal oxidative stress could trigger MS differentiation910. We additionally investigated the role of regulatory components in H 2 O 2 production and hypal polarized growth1112.…”

Engineering of an H2O2 auto‐scavenging in vivo cascade for pinoresinol production

“…Cells were harvested by centrifugation at 4000 g , 4°C for 5 min, resuspended in the same volume of precooled deionized water. Intracellular H 2 O 2 was released by sonicating on ice, measured using a hydrogen peroxide assay kit (Beyotime, Nantong, Jiangsu, China) (Liu et al, ), and normalized against the cytoplasmic volume using a standard ratio of 0.47 µL of internal volume per 1 mL of E. coli culture with OD 600 of 1.0 (Imlay and Fridovich, ).…”