Oxidation of self-stored carbohydrates and lipids provides the energy for the rapid morphogenetic transformation during asexual and infection-related development in Pyricularia oryzae, which results in intracellular accumulation of reducing equivalents NADH and FADH₂, requiring a cytosolic shuttling machinery towards mitochondria.  Our previous studies identified the mitochondrial D-lactate dehydrogenase MoDld1 as a regulator to channel the metabolite flow in conjunction with redox homeostasis.  However, the regulator(s) facilitating the cytosolic redox balance and the importance in propelling nutrient metabolite flow remain unknown.  The G-3-P shuttle is a conserved machinery transporting the cytosolic reducing power to mitochondria.  In P. oryzae, the mitochondrial G-3-P dehydrogenase Gpd2 was required for cellular NAD⁺/NADH balance and fungal virulence.  In this study, we re-locate the mitochondrial G-3-P dehydrogenase Gpd2 to the cytosol for disturbing cytosolic redox status.  Our results showed overexpression of cytosolic gpd2^Δmts without the mitochondrial targeted signal (MTS) driven by Ribosomal protein 27 promoter (PR27) exerted conflicting regulation of cellular oxidoreductase activities compared to the ΔModld1 deletion mutant by RNA-seq and prevented the conidiation and pathogenicity of P. oryzae.  Moreover, overexpression of gpd2^Δmts caused defects in glycogen and lipid mobilization underlying asexual and infectious structural development associated with decreased cellular NADH production and weakened anti-oxidation activities.  RNA-seq and non-targeted metabolic profiling revealed down-regulated transcriptional activities of carbohydrate metabolism and lower abundance of fatty acids and secondary metabolites in RP27:gpd2^Δmts.  Thus, our studies indicate the essential role of cytosolic redox control in nutrient metabolism fueling the asexual and infection-related development in P. oryzae.

This study aimed to investigate the interaction between maltodextrin/starch of different molecular weight distributions and soy protein isolate (SPI)–wheat gluten (WG) matrix during high-moisture extrusion.  Two maltodextrins (dextrose equivalent (DE): 10 and 20) and wheat starch were extruded with SPI–WG blend in a system of 65, 70, and 75% moisture to investigate their effects on texture and thermal stability.  Incorporating 5% maltodextrin (DE10) in the SPI–WG matrix improved the fiber structure and thermal stability.  When wheat starch was thoroughly gelatinized during subsequent sterilization, the fiber structure and thermal stability were also improved.  It was found that the plasticization caused by small-molecular weight saccharides and enhanced phase separation caused by large-molecular weight saccharides changed the melting temperature of blends and significantly improved the texture and thermal stability of extrudates.