UPR is a key cellular response for homeostatic adaptation to ER
stress. In this study, we examined the contribution of UPR to A. ory-
zae growth under conditions inducing secretory hydrolytic enzyme
production by constructing the ireA conditionally expressing strain.
The failure to obtain a homokaryotic ireA disruption mutant led us
to speculate that ireA disruption is lethal to A. oryzae. However, poor
growth of the nmtAp-ireA strain harboring a conditionally expressed
ireA construct was observed in the presence of thiamine even under
the secretion repressin