The Changes of Amino-Acid Metabolism between Wheat and Rice during Early Growth under Flooding Stress.

Floods induce hypoxic stress and reduce wheat growth. On the other hand, rice is a semi-aquatic plant and usually grows even when partially submerged. To clarify the dynamic differences in the cellular mechanism between rice and wheat under flooding stress, morphological and biochemical analyses were performed. Although the growth of wheat in the early stage was significantly suppressed due to flooding stress, rice was hardly affected. Amino-acid analysis revealed significant changes in amino acids involved in the gamma-aminobutyric acid (GABA) shunt and anaerobic/aerobic metabolism. Flood stress significantly increased the contents of GABA and glutamate in wheat compared with rice, though the abundances of glutamate decarboxylase and succinyl semialdehyde dehydrogenase did not change. The abundance of alcohol dehydrogenase and pyruvate carboxylase increased in wheat and rice, respectively. The contents of aspartic acid and pyruvic acid increased in rice root but remained unchanged in wheat; however, the abundance of aspartate aminotransferase increased in wheat root. These results suggest that flooding stress significantly inhibits wheat growth through upregulating amino-acid metabolism and increasing the alcohol-fermentation system compared to rice. When plant growth is inhibited by flooding stress and the aerobic-metabolic system is activated, GABA content increases.

Morphological, Biochemical, and Proteomic Analyses to Understand the Promotive Effects of Plant-Derived Smoke Solution on Wheat Growth under Flooding Stress.

Wheat is an important staple food crop for one-third of the global population; however, its growth is reduced by flooding. On the other hand, a plant-derived smoke solution enhances plant growth; however, its mechanism is not fully understood. To reveal the effects of the plant-derived smoke solution on wheat under flooding, morphological, biochemical, and proteomic analyses were conducted. The plant-derived smoke solution improved wheat-leaf growth, even under flooding. According to the functional categorization of proteomic results, oppositely changed proteins were correlated with photosynthesis, glycolysis, biotic stress, and amino-acid metabolism with or without the plant-derived smoke solution under flooding. Immunoblot analysis confirmed that RuBisCO activase and RuBisCO large/small subunits, which decreased under flooding, were recovered by the application of the plant-derived smoke solution. Furthermore, the contents of chlorophylls a and b significantly decreased by flooding stress; however, they were recovered by the application of the plant-derived smoke solution. In glycolysis, fructose-bisphosphate aldolase and glyceraldehyde-3-phosphate dehydrogenase decreased with the application of the plant-derived smoke solution under flooding as compared with flooding alone. Additionally, glutamine, glutamic acid, aspartic acid, and serine decreased under flooding; however, they were recovered by the plant-derived smoke solution. These results suggest that the application of the plant-derived smoke solution improves the recovery of wheat growth through the regulation of photosynthesis and glycolysis even under flooding conditions. Furthermore, the plant-derived smoke solution might promote wheat tolerance against flooding stress through the regulation of amino-acid metabolism.

Plant-derived smoke enhances plant growth through ornithine-synthesis pathway and ubiquitin-proteasome pathway in soybean.

To investigate the mechanism of promotive effect of plant-derived smoke on the soybean growth, a gel-free/label-free proteomics was performed. Smoke solutions were irrigated on soybean or supplied simultaneously with flooding stress. Morphological and physiological analyses were performed for the confirmation of proteomic result. Metabolomic change was investigated to correlate proteomic change with metabolism regulation. Under normal condition, the length of root including hypocotyl increased in soybean treated with 2000 ppm plant-derived smoke within 4 days, as well as nitric oxide content. Proteins related to protein synthesis especially arginine metabolism were altered; metabolites related to amino acid, carboxylic acids, and sugars were mostly altered. Integrated analysis of omics data indicated that plant-derived smoke regulated nitrogen­carbon transformation through ornithine synthesis pathway and promoted soybean normal growth. Under flooding, the number of lateral roots increased with root tip degradation in soybean treated with smoke solutions. Proteins related to ubiquitin-proteasome pathway were altered and led to sacrifice-for-survival-mechanism-driven degradation of root tip in soybean, which enabled accumulation of metabolites and guaranteed lateral root development during soybean recovery after flooding. These findings suggest that plant-derived smoke improves early stage of growth in soybean with regulation of ornithine-synthesis pathway and ubiquitin-proteasome pathway. BIOLOGICAL SIGNIFICANCE: Plant-derived smoke plays a key role in crop growth, however, the understanding of soybean in response to smoke treatment remains premature. Therefore, gel-free/label-free proteomic analysis was used for comprehensive study on the dual effect of smoke to soybean under normal and flooding conditions. Under normal condition, plant-derived smoke regulated nitrogen­carbon transformation through ornithine synthesis pathway and resulted in the increase of the length of root including hypocotyl in soybean within 4 days. Under flooding condition, plant-derived smoke induced inhibition of ubiquitin-proteasome pathway and led to sacrifice-for-survival-mechanism-driven degradation of root tip in soybean, which enabled accumulation of metabolites and promoted lateral root development during soybean recovery after flooding.

Texture of cooked rice prepared from aged rice and its improvement by reducing agents.

The textures of cooked rice prepared from aged rice grains and their improvement by reducing agents were investigated. For aged rice that was stored for 5 months without air by the operation of a vacuum packing machine, the stickiness/hardness ratio of cooked rice was as low as that of aged rice stored in air. The results of electrophoresis showed that oxidation of proteins in the former was advanced to the same degree as in the latter. The stickiness/hardness ratios of the aged rice were increased by the addition of sodium sulfite, cysteine, and dithiothreitol to the cooking water. Sodium sulfite, cysteine, and dithiothreitol cleave disulfide bonds to sulfhydryl groups. Therefore, cleaving disulfide bonds to sulfhydryl groups improved the texture. The addition of them to the cooking water also increased the extractable solids at the time of heating. Hence cleaving disulfide bonds to sulfhydryl groups must increase extractable solids. Consequently, the gelatinized paste layer thickened and the thick paste layer softened the cooked rice.

Purification and characterization of a thermostable raw starch digesting amylase from a Streptomyces sp. isolated in a milling factory.

A raw starch utilizing microbe was isolated from mud in a milling factory. The 16S ribosomal DNA (rDNA) sequencing and morphological properties of the strain indicated that it belongs to the genus Streptomyces. A strongly raw starch digesting amylase was purified from the culture supernatant of the strain by chromatographic procedures. The specific activity of the enzyme was 11.7 U/mg, molecular mass 47 kDa, optimum pH 6.0, and optimum temperature 50 to 60 degrees C. The enzyme showed sufficient activity even at 70 degrees C. It was activated by calcium, cobaltous, and magnesium ions, and inhibited by copper, nickel, zinc, and ferrous ions. It formed maltose mainly from raw and gelatinized starch, and glycogen. No products were formed from glucose, maltose, maltotriose, pullulan, or cyclodextrins (CDs). The enzyme digested raw wheat, rice, and waxy rice starch rapidly, and raw corn, waxy corn, sweet potato, tapioca, and potato starch normally.