CARC, Prairie View A&M University, P.O. Box 519–2008, Prairie View, Texas, 77446, USA.
Study area: Biochemistry, Biotechnology and Molecular biology.
Peanut is the ideal energy crop because its oil produces more biodiesel per acre compared with soy oil. But its great value as food, makes peanut oil very costly for biodiesel production. In order to optimize its fat and cellulosic biomass yields through biotechnology, the crop was treated with trace quantities of mineral nutrients as inducers of glutamate dehydrogenase (GDH) isomerization. The RNAs synthesized by GDH regulate the abundance of mRNAs homologous to them. Peanut seeds and shoots were analyzed for fat, cellulose, nucleotides and the RNA synthetic activity of GDH. The GDHsynthesized RNAs were Northern hybridized using as probes the GDHsynthesized RNAs homologous to mRNAs encoding acetyl CoA carboxylase (ACC, fat biosynthesis), phosphate translocator (cellulosic biomass), glucosyltransferase (dry matter yield), glycinamide ribonucleotide (GAR) synthetase/GAR transformylase (purine biosynthesis), and nitrate reductase (NR). Phosphate (20 mM) treatment induced GDH to synthesize RNAs that were homologous to mRNA encoding ACC thereby decreasing fat content by 6% compared with control peanut; but 5mM phosphate increased it by 13% equivalent to additional ∽100 gallons of biodiesel per ton of peanut. Phosphate (20 mM) minimized the GDH-synthesized RNAs homologous to the mRNA encoding phosphate translocator thereby increasing cellulosic biomass feedstock by 76% equivalent to additional ∽13.5Mj/kg of feedstock that is convertible to fuel ethanol. Treatment (25 mM NH4Cl) minimized the GDHsynthesized RNAs homologous to mRNA encoding glucosyl transferase thus increasing dry matter 11%. Nucleoside concentrations were low in the control peanut (2.4 ±0.1μg g−1 fresh mass) but increased in the Pi-treated (4.3 ±0.2) to the P&S-treated (7.3 ±0.3) and to the N-treated (8.4 ±0.5) according to the ratio of 2:4:7:8 in agreement with the trend of the GARS/GART probe copy number threshold ratio of 8:3:2:1, and in agreement with the trends of nutrient-optimized increases in dry matter and cellulosic biomass yields. The GDH-synthesized RNAs that were homologous to the mRNAs encoding GARS/GART, NR, and ACC shared extensive sequence homologies and had very high threshold concentrations in the control compared with mineral nutrient-treated peanuts. The cross-bindings between GDH-synthesized RNAs and mRNAs encoding enzymes in different metabolic pathways permitted the down regulation of metabolic fluxes through N-assimilation pathways (GARS/GART, NR) in order to optimize metabolic flux through ACCcatalyzed fat biosynthesis. Therefore the GDH-based biotechnology could considerably optimize oil and cellulosic biomass yields of peanut to satisfy food and bioenergy demands; the GDH-based biotech being the use of mg quantities of mineral nutrients/metabolites/inducers to differentially reprogram the RNAs synthesized by the enzyme so as to optimize a desired metabolic pathway while minimizing the flux through less-desired pathways.
Mineral nutrient, glutamate dehydrogenase, RNA synthesis, Northern hybridization, acetyl CoA carboxylase, lipoxygenase, phosphate translocator, glucosyltransferase, glycinamide ribonucleotide synthetase, purine nucleosides, nitrate reductase
