Characterisation and functional properties of Australian rice protein isolates

Albumin, globulin, glutelin and prolamin fractions were isolated from an Australian rice variety (cv. Langi) and characterised by yield, protein content and molecular weight profile using both capillary electrophoresis (SDS-CE) and sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE). The influence of pre-extraction enzymatic hydrolysis of starch and heating to 70 °C was also investigated, as was the extraction of the glutelin fraction without prior removal of the albumin and globulin fractions. Pre-extraction treatment affected mainly the albumin fraction, increasing dry matter yield but reducing protein content. SDS-CE was able to separate the protein fractions over a wider molecular weight range than SDS-PAGE, and the peaks from SDS-CE showed slightly higher molecular weight compared to equivalent bands from SDS-PAGE. The glutelin fraction extracted without prior removal of albumin and globulin fractions had different characteristics compared to those obtained by conventional extraction methods. Pre-extraction hydrolysis of starch did not significantly affect the emulsifying, foaming and gelling properties of extracted protein. Although rice glutelin had poor solubility, emulsifying and foaming properties in aqueous systems, it had good gelling properties which could be important for food applications.     

Stabilization of Tarom and Domesiah cultivars rice bran: Physicochemical,functional and nutritional properties

Extrusion is a multi-step thermal process which has been extensively utilized in food preparations. Effects of temperature, moisture content and speed screw on the stabilization of rice bran were optimized using response surface methodology. Furthermore, the effect of extrusion processing on the physicochemical, nutritional and functional properties of Tarom and Domesiah cultivars stabilized rice bran (SRB) were studied. The colour of rice bran was improved by extrusion processing, but the protein content was reduced, which can be related to the denaturation of protein. Extrusion had also a reduction significant effect on the phyitic acid and vitamin E in stabilized rice bran. However, the content of vitamins B₂, B₃, B₅ and folic acid were remained unchanged, but the dietary fibre was enhanced which has beneficial health effect. In comparison with raw rice bran, water holding capacity was enhanced, but the oil absorption capacity was reduced. Foaming capacity and foaming stability of SRB was more than that of untreated rice bran. Although, they were less than that of rice bran protein concentrate/isolate. As a result, extrusion process improves some functional and nutritional properties of rice bran which are valuable for industrial applications and have potential as food ingredient to improve consumer health.     

International Consortium of Rice Mutagenesis: resources and beyond

Rice is one of the most important crops in the world. The rice community needs to cooperate and share efforts and resources so that we can understand the functions of rice genes, especially those with a role in important agronomical traits, for application in agricultural production. Mutation is a major source of genetic variation that can be used for studying gene function. We will present here the status of mutant collections affected in a random manner by physical/chemical and insertion mutageneses.As of early September 2013, a total of 447, 919 flanking sequence tags from rice mutant libraries with T-DNA, Ac/Ds, En/Spm, Tos17, nDART/aDART insertions have been collected and publicly available. From these, 336,262 sequences are precisely positioned on the japonica rice chromosomes, and 67.5% are in gene interval. We discuss the genome coverage and preference of the insertion, issues limiting the exchange and use of the current collections, as well as new and improved resources. We propose a call to renew all mutant populations as soon as possible. We also suggest that a common web portal should be established for ordering seeds.     

Differences in functional properties and biochemical characteristics of congenetic rice proteins

Proteins in brown rice (BR), white rice (WR) and rice bran (RB) were extracted from the same paddy rice and investigated for their components, functional properties and chemical characteristics by SDS-PAGE methodology. BR and WR proteins possessed a poor solubility under weak acid conditions due to a high content of glutenin and richness in higher molecular-weight (MW) protein fractions. Rice bran protein contained significantly lower molecular-weight components (MWs < 50 kDa) than those in WR and BR. Nitrogen solubility, foaming and emulsification properties of their rice protein preparations were affected not only by pH (3–11), but also by the concentrations of NaCl (0.4–2.0%) and sucrose (4.0–20.0%). All of them, particularly rice bran protein, had favorable functional properties in the medium with a high salt or sugar concentration. Therefore, they have a good potential for development in the food industry.     

Comparison of functional and structural properties of native and industrial process-modified proteins from long-grain indica rice

Rice proteins, as a cheap plant protein source from the by-products of rice dreg processing, could potentially replace commonly used proteins such as soy and whey proteins in selected food products. In this study, the functional properties, surface hydrophobicity (H₀), sulfhydryl and disulfide bond contents, thermal properties, as well as secondary structures of native rice endosperm protein (REP) and processed rice dreg protein (RDP) extracted from long-grain indica rice, were compared. RDP was found to have a higher solubility associated with its relatively higher emulsifying and foaming properties than REP, as well as its water/oil holding capacity, although it was a denatured protein. The emulsifying properties were dependent on the solubility and H₀, while solubility was also related to the disulfide bond contents. Distinct differences in H₀, thermal properties, and disulfide bond contents between REP and RDP could be due to the conformational changes, as the industrial processing steps in the production of rice syrups caused an increase in β-turns at the expense of β-sheets and random coils of REP, leading to the unfolding of β-sheets into higher-ordered supramolecular structures for RDP, which could be responsible for its better functional properties.     

大豆转座子的研究现状及应用前景

大豆基因组中约有5万基因,大部分基因的功能处于未知状态。转座子插入突变体库的应用可以为解码大豆基因组中未知基因的功能提供研究平台,同时,也可以为创建有育种应用价值的大豆突变体种质资源库提供基础。大豆基因组中50%~60%的组分为转座子,其中具有活性的且结构完整的转座子只有Tgm9。大豆转座子突变体库目前主要还是利用外源转座子来建立,但是开发并改进内源转座子,增加其跳跃能力及稳定性,可以成为构建突变体库的一个新方向。本文主要介绍了大豆基因组中发现的各种转座子及其特点,并且重点讨论了外源转座子和大豆内源转座子在大豆突变体库创建中的应用现状及应用前景。     

Characterization of rice storage proteins by SE-HPLC and micro z-arm mixer

While the effect of protein content and composition on the functional properties of wheat flour is well studied, our knowledge on the same properties of rice flour is limited. This work was conducted to study the relationship between the dough mixing properties of flour from different rice cultivars and protein content and composition. An efficient sonication-based two-step extraction procedure was applied to isolate rice flour proteins. The size-exclusion HPLC (SE-HPLC) method, originally developed for separating wheat proteins, was applied with some minor modifications in order to study the size distribution of rice flour proteins. Four fractions were distinguished on the SE-HPLC profile and were further characterized by SDS-PAGE. Fractions I–III consisted of glutelins, while fraction IV contained albumin, globulin and prolamin proteins. When rice dough was characterized on the basis of mixing parameters in a micro z-arm mixer, significant differences were observed depending on the protein composition of the flour. Statistical analysis results indicated that the functional properties of the flour from different rice cultivars were associated with the amount of polymeric proteins and their size distribution.     

Integration of independent component analysis with near infrared spectroscopy for evaluation of rice freshness

The storage time and conditions of rice has an enormous effect on its appearance, flavor, and quality of the nutrients; and the acidity of rice usually increases with prolonged storage. Therefore, evaluation of freshness is an important issue for rice quality. In this study, the NIR (near infrared) spectra combined with independent component analysis (ICA) technique was used to evaluate the rice freshness. A total of 180 white rice samples were collected from 6 crop seasons for the purpose of developing an ICA-NIR based procedure for rice freshness as quantified by pH values. Values of pH were determined by a BTB-MR (bromothymol blue – methyl red) method. The best calibration model of white rice was developed using the smoothed first derivative spectra, five ICs and cross-validation; the results indicated that r² (coefficient of determination) = 0.924, and in units of pH, SEC (standard error of calibration) = 0.145, SEP (standard error of prediction) = 0.146, bias = 0.001, and RPD (residual predictive deviation) = 3.65. Freshness of white rice could be distinguished either visually by a 3-dimensional diagram composed from ICs 2, 3 and 4, or statistically by a calibration model. The results show that ICA with NIR has the potential to be adopted as an effective method for evaluating rice freshness.     

Characterization of xylan from rice bran and finger millet seed coat for functional food applications

The purpose of this work is to establish alternative renewable resources by a process of chemical free water based extraction of xylan which is an important plant component with diverse industrial applications including food and pharmaceuticals ones. In this respect, we have shown an alternative source of water soluble xylan (WSX) from rice bran which is usually wasted and seed coat of underutilized finger millet. Extractions were carried out using water at ambient temperature (25 ± 2° C). Hydrolysis and derivatization of the extracted WSX revealed the predominance of xylose followed by arabinose and glucose, with Ara/Xyl molar ratios of 0.55 and 0.68 respectively. Elemental analysis showed similarities in carbon and hydrogen, while nitrogen and sulfur contents showed some variations. Structural identification of β - glycosidic linkages and acetyl groups from the FTIR spectrum; β-D-1, 4-xylopyranose backbone with α-L-arabinofuranose and 4-0-methylglucuronic acid substituents evident from ¹H and ¹³C NMR confirmed the presence of xylan. Characteristics of the extracted WSX (SEM, particle size, XRD and TGA) showed similarities in the two sources. Thus both rice bran and finger millet seed coat are potential sources of xylan and further optimization of the process can provide economic and environmental benefits.     

灰色评判在水稻育种中的应用

运用灰色系统的理论与方法,根据水稻育种目标。对杂交水稻F1代测配组合的主要农艺性状进行灰色评判,筛选高产优良杂交稻组合,为水稻品种的早期选育提供理论依据。     

HSC法与稳定性参数在水稻区试中的应用

采用高稳系数法 ,辅以稳定性系数和适应性参数 ,对 1999年重庆市水稻区试结果进行了综合分析和评价 ,结果表明 :K优 88, 优缙恢 1号 , 优 R99, 优 5 0 32 9为高产稳产性品种 ;C优 2 2为高产不稳定品种 ; 优 95 - 2 ,6 5 0 0 2为低产稳定性品种 ,同时也表明 HSC法较之方差法更能客观反映水稻品种高产、稳产性 ,计算更为简单。     

Total phenolics,flavonoids, antioxidant capacity in rice grain and their relations to grain color,size and weight

Total phenolics, flavonoid contents and antioxidant capacity from a wide collection of rice germplasm were measured, and their relations to grain color, grain size and 100-grain weight were investigated. Highly significant genotypic differences were observed in total phenolics, flavonoid contents and 2,2-azino-bis-(3-ehylbenzothiazoline-6-sulphonic acid) diammonium salt (ABTS) radical cation antioxidant capacity. They displayed an increasing order in the white rice, red rice and black rice, yet several white rice had higher phenolics and flavonoids contents than the red rice. Significant positive pair-wise correlations were found among the phenolics, flavonoid contents and antioxidant capacity, and the coefficient between the phenolic contents and antioxidant capacity was extremely high (r = 0.96). Among all rice accessions, the grain color parameters had negative correlations with the phenolics, flavonoid contents and antioxidant capacity (p < 0.001). The negative correlation between a* and antioxidant capacity, and the positive correlation between H° and antioxidant capacity were consistent within the respective white rice and red rice groups. Flavonoid contents had positive correlation with grain length and length to width ratio, and had negative correlation with the 100-grain weight among all rice accessions. It was also found that 100-grain weight still had negative correlations with phenolics, flavonoid contents and antioxidant capacity within the white rice genotypes. These relationships may serve as indexes to indirectly select breeding lines high in the phenolics, flavonoids and antioxidant capacity. Principal component analysis including the information for phenolics, flavonoids, antioxidant capacity, grain color parameters, grain size and 100-grain weight extracted five principal components that explained 83.7% of the total variances. The results of this study may provide new opportunities for rice breeders and eventually commercial rice growers to promote the production of rice with enhanced nutritional quality.     

转基因技术在大豆性状改良上的应用

随着我国大豆需求量的逐年增加,培育超高产、优质、高抗性品种的需求变得越来越迫切。基因工程方法的应用为作物遗传育种开辟了一条新的道路,通过转基因技术,将控制优良性状的基因整合到作物基因组中,培育转基因植株,可以准确的、有目的对作物的农艺性状进行定向改良。近年来,功能基因组学的发展为转基因技术提供了新的指导。本文着重讲述了大豆遗传转化方法的新方向,同时介绍了国内外转基因技术在大豆性状(抗除草剂、抗虫、抗病、抗逆、品质性状等)改良中的研究进展,并对未来大豆转基因方向进行了展望。     

Development of new markers to genotype the functional SNPs of SSIIa, a gene responsible for gelatinization temperature of rice starch

Gelatinization temperature (GT) is an important quality predictor that determines the cooking quality of rice. GT is genetically controlled by the starch synthase IIa (SSIIa) gene. Two functional single nucleotide polymorphisms (SNPs) inside the SSIIa have already been found to be responsible for the variation of GT. One of these, GC/TT SNP at 4329/4330 bp, could be genotyped by four primers in a single PCR ( Bao et al., 2006a), but another one, G/A SNP at 4198 bp, has not been detected by a PCR-based marker. Here, we developed cleaved amplified polymorphic sequence (CAPS) and derived cleaved amplified polymorphic sequence (dCAPS) markers to detect these SNPs. A dCAPS marker that the PCR products were cleaved by the BseR I restriction endonuclease was designed to detect GC/TT SNP. Both CAPS and dCAPS markers were designed to detect G/A SNP using the restriction endonuclease Nla III and Tsp45 I, respectively. All the markers developed were co-dominant. It was known that the A allele of G/A SNP was rare among rice germplasm, but it was still in use by rice breeders. 11 rice accessions including landrace and breeding lines with A allele of G/A SNP were detected. The F₂ individuals from two crosses were used to analyze the co-segregation between the SNP alleles and the GT. The segregation ratio of two SNPs did not conform to the expected Mendelian ratio of 1:2:1, but the SNPs were co-segregated with GT. The markers developed in the present study would be useful in molecular breeding for the improvement of the quality of rice grain.     

Gene response in rice plants treated with continuous fog influenced by pH,was similar to that treated with biotic stress

Background

Throughout Asia, including Japan, rice plants are cultivated in a wide range of areas from lowlands to highlands and are frequently exposed to fog, including acid fog. Some physiological studies have shown that acid fog can be a stress factor for plants. We analyzed the gene expression profiles of rice plants treated with artificially prepared simulated acid fog (SiAF) or simulated neutral fog (SiNF) for 1 or 7 days.

Results

Microarray analysis results suggested that both the SiAF and the SiNF treatments induced the expression of genes involved in the defense and stress responses in rice plants. Induction of such genes was detected in plants treated with SiAF for 1 day, and the number of induced genes increased in plants treated with SiAF for 7 days. The genes for defense and stress responses were also induced by SiNF for 7 days, although they were not induced by SiNF for 1 day. The gene expression profiles of the SiAF-treated and the SiNF-treated plants were compared to those of plants treated with other stress factors. The comparison revealed that both SiAF and SiNF treatments have similar effects to biotic stresses and ozone stress. The genes encoding NADPH oxidase and germin, which function in apoplasts, were also induced by SiAF, SiNF and biotic stresses.

Conclusions

These findings suggest that both the SiAF and the SiNF treatments may result in oxidative stress through the apoplastic production of reactive oxygen species.     

Risk analysis of pesticides applied to rice paddies using RICEWQ 1.6.2v and RIVWQ 2.02

Rice is commonly cultivated in Southern Europe in large river basins where the extensive use of herbicides may impact water quality at basin scale level. Consequently, pesticide risk assessment would be more relevant when considering a rice cultivation area as a whole. Accordingly, two watershed-scale scenarios were developed to represent the specific agronomic, water and pesticide management practices of rice cultivation in Greece. These scenarios were utilized for the parameterization of the rice water quality model (RICEWQ) 1.6.2v and the surface water model river water quality (RIVWQ) 2.02. in order to predict the environmental concentrations of pesticides in groundwater (GW) and surface water (SW) systems within a rice area. The annual average pesticide concentrations at 1 m depth, predicted by RICEWQ were used to assess the risk for GW contamination. The predicted exposure concentrations derived through modelling and eco-toxicological endpoints obtained from the literature, were used to calculate acute and long-term toxicity exposure ratios (TERs) for aquatic organisms. Application of these scenarios with RICEWQ and RIVWQ models enabled us to perform a risk assessment exercise for several herbicides registered in Greece for use in rice. Such a risk assessment approach could be further scaled up to represent a whole rice cultivated basin in order to be used for regulatory purposes.     

Bacillolysin,papain, and subtilisin improve the quality of gluten-free rice bread

Protease has been shown to be an effective food additive for improving the quality of gluten-free rice bread. In this study, we found that bacillolysin (Protin SD-NY10, metallo protease), papain (cysteine protease), and subtilisin (Protin SD-AY10, serine protease) increased the specific volume of gluten-free rice breads by 30–60% compared with untreated breads. These proteases also decreased crumb hardness by 10–30% compared with untreated breads. Many fine bubble cells were observed in the crumb of the protease-treated rice breads using scanning electron microscopy. Optical microscopic observation revealed fine networks of small protein aggregates stained by Coomassie Brilliant Blue (CBB) in the rice batter of the improved gluten-free rice breads. Sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) of protein in the rice batter suggested that the amount of low molecular weight proteins (less than 10 kDa) increased with the use of Protin SD-NY10, Protin SD-AY10 and papain treatments compared with untreated rice batter. Thus, we considered that the small proteins aggregates were formed through disulfide bonds. This fine network was effective for retaining CO₂ gas during the fermentation process, resulting in an increase in the specific volume and a decrease in the crumb hardness of gluten-free rice bread.     

不同产地香米微量元素含量差异及吸收富集特征研究

对特种水稻“江永香稻”的根、茎、米与土壤中的 11种微量元素含量进行了分析。结果表明 ,江永香稻茎、根对 Mn,As,Zn等元素富集能力特别强 ,对 Pb元素富集能力次之 ;江永香米对 Zn,Mn等元素吸收能力强 ,因此香米的 Zn,Mn含量均比普通稻米的高     

Effects of semidry flour milling on the quality attributes of rice flour and rice noodles in China

To investigate the effects of semidry-milling on the quality attributes of rice flour and rice noodles, the properties of rice flours and cooking properties of rice noodles prepared with wet-, dry- and semidry-milled rice flours were characterized. The level of starch damage of semidry-milled rice flour at 30% moisture was significantly decreased to the level of wet-milled rice flour (P < 0.05); the whiteness of dry-milled rice flour was decreased compared with wet-milled rice flour (P < 0.05), while that of semidry-milled rice flour was not; the wet- and semidry-milled rice flours showed similar morphology and water hydration properties; the dry milling method reduced significantly the hardness, chewiness, and resilience of rice noodles (P < 0.05) compared with wet-milling, but semidry-milling did not; the cooking qualities of rice noodles produced by semidry-milling were comparable to wet-milling. It indicated the semidry-milling at 30% moisture may provide the protective effects on the characteristics of rice flours, which could be used to produce similar qualities of rice noodles to the wet-milling.