Changes in protein and carbohydrate content during development of seeds and siliquas of rapeseed (Brassica napus L.)

Abstract

A study was made on the changes observed in the protein, starch and soluble sugar content during development of siliquas and seeds of rapeseed grown in central Italy.

Concentration of starch and soluble sugars in the seed increases to 75 per cent dry matter during the first few weeks of pod development and then drops to minimum values. The protein increases steadily until maturity, when a level of 0.85 mg per seed is reached, equivalent to 18 per cent dry matter. The protein and starch in the hull? decrease continuously during development, while in the initial stages the soluble sugars are accumulated until they account for 33 per cent dry matter, after which they decline towards maturity.     

Some molecular properties of plant starch phosphorylases and the levels of activity of the multiple forms

A number of plant tissues have two phosphorylase fractions (I and II) that can be separated by DEAE-cellulose chromatography. When only one is detectable, it corresponds to enzyme II. Peas differed from other legumes in showing an increase in enzyme I during seed germination. Examination of the I type enzymes, by sodium dodecyl sulphate polyacrylamide gel electrophoresis, sector cell ultracentrifugation and gel filtration, indicated that these were dimers composed of similar sub-units of MW near 90 000. When phosphorylase II enzymes were examined, the sub-unit MW was found to be higher, near 110 000 and, whereas ultracentrifugation techniques indicated a dimer of similar sub-units for the native enzyme, gel filtration gave higher MW values. Phosphorylase II from Victory Freezer peas differed from the other samples, in being able to form mixtures of dimer and tetramer.     

Simultaneous amylase production,raw cassava starch hydrolysis and ethanol production by immobilized Aspergillus awamori and Saccharomyces cerevisiae in a novel alternating liquid phase–air phase system

As a solution to the problems of mass transfer limitation in submerged cultures and scale up of solid-state/liquid-surface cultures, an alternating liquid phase–air phase bioreactor was developed. It consisted of a bioreactor equipped with a siphon system and a reservoir. Aspergillus awamori was immobilized in loofa sponge inside the bioreactor and culture broth was pumped from the reservoir into the bioreactor. Each time the culture broth level reached a critical level, the broth automatically siphoned back into the reservoir. Thus the immobilized cells were alternatingly submerged and exposed to air. The duration of each phase was controlled by the pumping rate and with an on-off timer. During amylase production from soluble starch and raw cassava starch, the optima ratios of the liquid to air phases were 12 h : 12 h and 3 h : 6 h respectively. Saccharomyces cerevisiae IR2 was immobilized in the reservoir and the system was used for simultaneous amylase production, hydrolysis and ethanol production from raw cassava starch. The process was very stable for more than 7 batches with high ethanol yield of 0.46 g-ethanol/g-starch and productivity of 1.73 g-ethanol/L/h. These values are high, the system can be scaled up, and thus it has many potential applications.     

利用外源γ-氨基丁酸调控海洋绿藻亚心形四爿藻淀粉积累

微藻被看作第三代生物质能源的来源。微藻淀粉结构与高等植物的高度相似性使其可以作为粮食作物的替代,在生物能源领域有广泛的应用。γ-氨基丁酸(GABA)被认为是一种信号分子,可以调节植物细胞的生长代谢。本研究在缺氮培养条件下添加外源GABA调控海洋绿藻亚心形四爿藻生理代谢和淀粉积累。结果表明,添加外源GABA可以抑制细胞生长,降低光合作用效率;OJIP实验显示,GABA的添加增强了光合器官能量耗散,降低了光能利用效率,阻碍了电子传递,造成额外胁迫,从而促使细胞将碳流更多地分配到淀粉积累,导致藻细胞的淀粉含量、淀粉产量和淀粉产率提高。添加10 mmol/L GABA获得最大淀粉含量39%DW,比未添加GABA的对照组淀粉含量提高39%;同时获得最大淀粉产量和产率为1.72 g·L^-1和0.36 g·L^-1·d^-1,分别比未添加GABA的对照组提高39%和50%。以上结果表明在缺氮条件下添加外源GABA是一种调控亚心形四爿藻细胞代谢并提高其淀粉生产的有效方法。     

Constitutive expression of cell wall invertase genes increases grain yield and starch content in maize

Grain size, number and starch content are important determinants of grain yield and quality. One of the most important biological processes that determine these components is the carbon partitioning during the early grain filling, which requires the function of cell wall invertase. Here, we showed the constitutive expression of cell wall invertase–encoding gene from Arabidopsis, rice (Oryza sativa) or maize (Zea mays), driven by the cauliflower mosaic virus (CaMV) 35S promoter, all increased cell wall invertase activities in different tissues and organs, including leaves and developing seeds, and substantially improved grain yield up to 145.3% in transgenic maize plants as compared to the wild‐type plants, an effect that was reproduced in our 2‐year field trials at different locations. The dramatically increased grain yield is due to the enlarged ears with both enhanced grain size and grain number. Constitutive expression of the invertase‐encoding gene also increased total starch content up to 20% in the transgenic kernels. Our results suggest that cell wall invertase gene can be genetically engineered to improve both grain yield and grain quality in crop plants.     

Evolution of 1, 3, 5-trisubstituted bipyrazole scaffold based platinum(II) complexes as a biological active agent

Abstract

Square planar mononuclear platinum(II) complexes having general formula [Pt(Lⁿ)Cl₂], (where, Lⁿ?=?L^1–4) were synthesized with neutral bidentate heterocyclic 1,3,5-trisubstituted bipyrazole based ligands. The synthesized compounds were characterized by physicochemical method such as TGA, molar conductance, micro-elemental analysis and magnetic moment, and spectroscopic method such as, FT-IR, UV–vis, ¹H NMR, ¹³C NMR and mass spectrometry. Biological applications of the compounds were carried out using in vitro brine shrimp lethality bioassay, in vitro antimicrobial study against five different pathogens, and cellular level cytotoxicity against Schizosaccharomyces pombe (S. Pombe) cells. Pt(II) complexes were tested for DNA interaction activities using electronic absorption titration, viscosity measurements study, fluorescence quenching technique and molecular docking assay. Binding constants (K_b) of ligands and complexes were observed in the range of 0.23–1.07?×?10⁵?M^?1 and 0.51–3.13?×?10⁵?M^?1, respectively. Pt(II) complexes (I–IV) display an excellent binding tendency to biomolecule (DNA) and possess comparatively high binding constant (K_b) values than the ligands. The DNA binding study indicate partial intercalative mode of binding in complex-DNA. The gel electrophoresis activity was carried out to examine DNA nuclease property of pUC19 plasmid DNA.     

Reduction of Nitrate in Agricultural Soils by Bio-electrokinetics

High nitrate concentration in surface soils is a serious concern for the agricultural industry throughout the world. Nitrate reduction can be achieved by chemical or biological processes; however, these processes are difficult to achieve in-situ because of the low permeability of clays. This study evaluates bio-electrokinetic processes for nitrate treatment in low-permeability soils. The concept is based on using iron electrodes to generate an electric field and a reducing environment in the soil to facilitate nitrate reduction by existing bacteria. Experiments were conducted using starch as an additive for microbial activity in the anolyte. Three sets of experiments were conducted under 0.5, 1.0, and 2.0 V cm^?1 voltage gradient, and using starch as an anolyte for enhancing existing microbial activity in the soil. Initial nitrate concentration in the soil (agricultural soil collected from Jinju, Korea) was between 782 and 800 mg kg^?1. Removal of 100% nitrate was achieved in the soil under 0.5 and 1.0 V cm^?1 due to the combined effect of biological and iron reduction. A control experiment with iron electrodes, but without starch, was not as effective. Ammonium was also effectively removed by the combined action of starch and iron under 0.5 and 1.0 V cm^?1. The role of starch with iron on the nitrate and ammonium removal process is evaluated along with the role of transport by electro-osmosis and electro-migration. The bacterial action on denitrification and nitrification is assessed and the relationship between pH and the efficiency of nitrate reduction in the bio-EK systems is evaluated.     

小麦地方品种淀粉颗粒结合蛋白及淀粉含量差异研究

淀粉颗粒结合蛋白包含了多种淀粉生物合成的关键酶,对作物淀粉品质有重要影响。本研究利用1D-SDS-PAGE,分离了74份四川、西藏及云南毗邻地区小麦的淀粉颗粒结合蛋白,对突变材料进行了分子标记检测,对总淀粉和直链淀粉含量差异进行了比较。发现供试材料中,在分子量57～130 kDa区域共有9种不同的蛋白条带。其中,2个条带可能为新的淀粉颗粒结合蛋白;存在12份Wx-B1缺失的自然突变体和3份稀有的SGP-B1缺失突变体;筛选到直链淀粉含量超过30%的材料2份,直链淀粉含量为15%左右的材料10份。这些材料为小麦淀粉品质改良及淀粉生化合成机理研究提供了基础。     

Carbon starvation reduces carbohydrate and anthocyanin accumulation in red-fleshed fruit via trehalose 6-phosphate and MYB27

Kiwifruit (Actinidia spp.) is a recently domesticated fruit crop with several novel-coloured cultivars being developed. Achieving uniform fruit flesh pigmentation in red genotypes is challenging. To investigate the cause of colour variation between fruits, we focused on a red-fleshed Actinidia chinensis var. chinensis genotype. It was hypothesized that carbohydrate supply could be responsible for this variation. Early in fruit development, we imposed high or low (carbon starvation) carbohydrate supplies treatments; carbohydrate import or redistribution was controlled by applying a girdle at the shoot base. Carbon starvation affected fruit development as well as anthocyanin and carbohydrate metabolite concentrations, including the signalling molecule trehalose 6-phosphate. RNA-Seq analysis showed down-regulation of both gene-encoding enzymes in the anthocyanin and carbohydrate biosynthetic pathways. The catalytic trehalose 6-phosphate synthase gene TPS1.1a was down-regulated, whereas putative regulatory TPS7 and TPS11 were strongly up-regulated. Unexpectedly, under carbon starvation MYB10, the anthocyanin pathway regulatory activator was slightly up-regulated, whereas MYB27 was also up-regulated and acts as a repressor. To link these two metabolic pathways, we propose a model where trehalose 6-phosphate and the active repressor MYB27 are involved in sensing the carbon starvation status. This signals the plant to save resources and reduce the production of anthocyanin in fruits.     

Diurnal patterns of growth and transient reserves of sink and source tissues are affected by cold nights in barley

Barley is described to mostly use sucrose for night carbon requirements. To understand how the transient carbon is accumulated and utilized in response to cold, barley plants were grown in a combination of cold days and/or nights. Both daytime and night cold reduced growth. Sucrose was the main carbohydrate supplying growth at night, representing 50–60% of the carbon consumed. Under warm days and nights, starch was the second contributor with 26% and malate the third with 15%. Under cold nights, the contribution of starch was severely reduced, due to an inhibition of its synthesis, including under warm days, and malate was the second contributor to C requirements with 24–28% of the total amount of carbon consumed. We propose that malate plays a critical role as an alternative carbon source to sucrose and starch in barley. Hexoses, malate, and sucrose mobilization and starch accumulation were affected in barley elf3 clock mutants, suggesting a clock regulation of their metabolism, without affecting growth and photosynthesis however. Altogether, our data suggest that the mobilization of sucrose and malate and/or barley growth machinery are sensitive to cold.