禾本科作物糯性的研究进展

综述目前禾本科作物糯性的研究进展。水稻、小麦、玉米、大麦、谷子、高粱在糯性基因定位及淀粉遗传情况。糯性品种在应用中的价值。为育种者提供一些理论依据并提出一些建议。     

大麦和小麦抗病性的分子基础研究进展

抗病性是大麦和小麦不可或缺的重要性状。本文介绍了大麦和小麦的抗病分子基础研究进展:从大麦和小麦分离出的抗病基因编码蛋白的结构具有相似性及独特性;从大麦中鉴定、分离出抗病基因介导、激活防御反应所必需的一些附加基因,并发现在双子叶植物与禾谷作物的抗病防御反应中一些信号传导基因具有保守性,有利于对大麦和小麦抗病信号传导途径的理解和同源基因的分离;从大麦和小麦中分离出病原诱导表达的一些防卫基因。本文讨论了利用已克隆的抗病基因结构保守性和比较基因组学进一步分离克隆大麦和小麦抗病基因的潜力与限制以及利用克隆的抗病基因进行生物工程育种的可能性与局限性;还提出了今后发展方向,即不仅将继续深入研究显性单基因的分子机制,还将揭示持久的多基因抗性和广谱的非寄主抗性的分子基础。     

Preliminary trials using a white clover (Trifolium repens L.) understorey to supply the nitrogen requirements of a cereal crop

A method of growing cereals with no input of N fertilizer was tested. Two experiments are reported in which white clover ( Trifolium repens L.) was used to supply the nitrogen requirements of the cereal. Spring barley, spring oats and winter barley were direct drilled into an established clover crop and grown with the legume as an understorey. The yield of whole crop cereal, for ensilage, and yield of cereal grain were similar to those grown by traditional methods. In the first experiment, clover survived adequately to be used again, but in the second experiment it was killed by a very high slug population. A method of slug control by mob stocking with sheep is discussed. Where clover survived, no weed, insect or disease problems were encountered. The technique offers a possible method of reducing the environmental problems arising from the use of nitrogen fertilizers.     

禾谷镰刀菌侵染拟南芥的研究

本研究采用禾谷镰刀菌侵染拟南芥,结果表明,在拟南芥开花初期,采用分生孢子悬浮液喷雾接种,能够引起花组织和角果产生病变,菌丝进一步扩展到整个植株中,最终引起植株坏死。用组织染色及特异引物进行PCR扩增,证实接种菌已侵入植物组织。说明拟南芥可用来进行禾谷镰刀菌侵染过程的相关分析,也可为筛选抗赤霉病的基因提供新思路。     

The effect of combined infestation by cereal aphids (Macrosiphum avenae (Fabr.) (Sitobion avenae) and Rhopalosiphum padi (L.)) and cereal leaf beetles (Oulema melanopus (L.)) on their population development and on yield of winter wheat

Previous clarification of the relationships between insect populations and damage by cereal pests has enabled the effect of combined pest infestation on the yield of winter wheat to be analysed more thoroughly. The cereal aphids Macrosiphum avenae (Fabr.) (Sitobion avenae) and Rhopalosiphum padi (L.), each in combination with the cereal leaf beetle Oulema melanopus (L.), were investigated in pot trials which enabled interactions between the combined pest populations to be studied also. Although intraspecific competition was observed for each pest population, there was no interspecific adverse effect of density on population increase. With increasing population densities of the pests in combination, the relative contribution of each species to the combined yield losses decreased. Consequently, there was no summation of individual losses, but a reduction of up to 24·3%. The ability of the cereal plant to compensate for losses may be responsible for this ‘buffering effect’, which apparently is attributable to increased dry-matter production in the presence of large combined pest populations. These results suggest that the existing economic thresholds relating to the effects of cereal aphids and cereal leaf beetle on yields of winter wheat require modification.     

Insights from in vitro exploration of factors influencing iron,zinc and provitamin A carotenoid bioaccessibility and intestinal absorption from cereals

Developments in genetics, agronomics and processing has positioned staple cereals as important sources of iron, zinc and provitamin A (pVA) carotenoids for nutritionally vulnerable populations. Significant effort has been placed on understanding the bioavailability of these micronutrients from cereal foods, including the exploration of underlying mechanisms by which their bioavailability can be modified. While micronutrient bioavailability is preferably assessed in clinical trials, relevant in vitro digestion and intestinal cell culture models have been applied to study effects of genetic, agronomic, post-harvest and food processing on micronutrient bioavailability. This review (1) critically assesses the application of in vitro models in the exploration of mechanisms associated with iron, zinc and provitamin A carotenoid bioaccessibility and intestinal absorption from cereal foods, and (2) identifies remaining gaps in order to frame future strategies to improve the nutritional impact of cereal foods.     

The effects of dietary fibre addition on the quality of common cereal products

Cereal products are consumed daily by the majority of the population. Popular belief is that these cereal products, rich in carbohydrates, produce a high glycaemic response and may not be a contributing factor to the obesity epidemic throughout the world. Recently the food industry has investigated ways of improving the overall nutritional balance of carbohydrate rich foods and focused on increasing their dietary fibre (DF) contents at the expense of readily digestible carbohydrates. It is well documented that dietary fibre is involved in disease prevention and enhanced health of consumers. Moreover, the food industry can take advantage of the physicochemical properties of fibre to improve the viscosity, texture, sensory characteristics and shelf-life of their products. The focus of this review paper is on the influence of DFs (inulin, fructo-oligofructose, β-glucans, arabinoxylans and resistant starch) supplementation on the quality and nutritional aspects of common foods containing cereals- pasta, bread, muffins/cakes and extruded snacks. This review reports on the evidence regarding fibre enrichment of cereal foods and looks at the advances and future trends in enriched dietary fibre cereal products.     

不同地区禾谷孢囊线虫对不同类型杀线剂的敏感性

为明确不同地区禾谷孢囊线虫对不同类型杀线剂的敏感性,采用浸渍法分别测定了灭线磷、噻唑膦、涕灭威、丁硫克百威、阿维菌素及甲维盐六种药剂对河南清丰、河北保定、安徽颍上、山东泰安和青岛五个地区的禾谷孢囊线虫二龄幼虫的室内毒力。结果表明,六种杀线剂对五个地区线虫的毒力表现为:甲维盐>阿维菌素>灭线磷>涕灭威>噻唑膦>丁硫克百威。灭线磷、噻唑膦、涕灭威和丁硫克百威对各地区线虫的LC50值都在582.7mg.L-1以上,不同地区线虫对同一药剂的敏感性存在一定差异,但相对毒力指数均在1.31以下;阿维菌素对各地区线虫的LC50值为26.0～66.3mg.L-1,甲维盐对各地区线虫的LC50值为20.1～35.3mg.L-1,不同地区线虫对这两种药剂的敏感性存在较大差异,相对毒力指数最高达2.55。     

Transgenic Expression of the Recombinant Phytase in Rice （Oryza sativa）

In many plants, phytic acid (phytate, 1, 2, 3, 4, 5, 6-hexakisphosphate) is one of the main storage forms of phosphate. About 80% of phosphorus (P) in cereal plants, including rice is stored as phytic acid [1-2]. P in phytic acid can’t be utilized by monogastric animals including human, while it was estimated that only 1/3 of the total P in most of the vegetal feedstuff could be efficiently utilized by the livestock. Therefore, for animal feed with P supplementation is expected to meet the d…     

Study on nonenzymatic browning in cookies,crackers and breakfast cereals by maltulose and furosine determination

Nonenzymatic browning development has been investigated in commercial cookies, crackers and breakfast cereals by determination of maltulose and furosine. In addition, maltose, lactose, lactulose, fructose, glucose and 2-furoylmethyl-GABA were also determined in the samples studied. Maltulose and furosine were present in all samples of cookies, crackers and breakfast cereals. Differences found among samples may be attributed to variations in composition and processing conditions. The maltose/maltulose ratio showed a wide range in the samples studied and could probably be attributed to differences in heating intensity during processing. Thus, maltose/maltulose ratio might serve as indicator of the heat load during manufacture. Furosine and 2-furoylmethyl-GABA may arise from Maillard reactions in some of the ingredients before manufacture of the cereal products: this appears to be a major drawback for the use of these compounds as suitable indicators to differentiate between commercial cereal products. However, in the cereal industry, where exact ingredient composition is known, measurement of the maltulose and furosine formed might be used as indicators to monitor processing conditions during the manufacture of cereal products.     

Direct measurement of the total antioxidant capacity of cereal products

A simple and rapid procedure was developed for the direct measurement of the antioxidant capacity of cereals. It entails grinding of cereals, mixing with 2,2′-azinobis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) reagent, centrifugation and measure of the absorbance. The ABTS reagent was dissolved in a mixture of ethanol:water (50:50, v/v), instead of 100% ethanol, in order to overcome low solubility of water-soluble antioxidant compounds of some cereals. A reaction time of 30 min allowed plateau values to be reached during the antioxidant capacity measurement of cereal samples. The accuracy of the direct procedure was confirmed by measuring, in solid state, the antioxidant activity of pure phenolic compounds.The direct procedure gave results of total antioxidant capacities significantly higher than those determined by the traditional procedure (multiple extraction followed by alkaline hydrolysis) for most whole meal cereals, suggesting that such a procedure was not always sufficient to properly assess the antioxidant capacity of bound phenolic compounds in cereals. The proposed extraction-independent procedure for measuring antioxidant capacity of cereals will facilitate the inter-laboratory data comparison, the construction of reliable antioxidant capacity database and the screening of large sampling of cereals for their nutraceutical characteristics.     

Variation in Granule Bound Starch Synthase I (GBSSI) loci amongst Australian wild cereal relatives (Poaceae)

A complex cascade of enzymes is responsible for the development of starch granules in grain endosperm. Granule Bound Starch Synthase I (GBSSI), encoded by the Waxy gene, is a key enzyme of starch synthesis and determines the accumulation of amylose in the starch granules. The complete genomic GBSSI sequence was ascertained for eight Australian cereal wild relatives (CWR) to determine diversity within the gene. A phylogeny derived from the coding sequence of the entire Waxy gene was compared to established phylogenetic relationships. Starch granule morphology observed in conjunction with this phylogeny suggests that small polygonal starch granules arranged as compound granules are the ancestral state, evolving subsequently to bimodal starch granules and to larger simple granules. Genomic sequence length varied within the species from 2800 to 3572 bp. Most variation occurred within the intron sequences, the largest insertion showing strong homology to a retrotransposon. One wild species was determined to have a deletion in the 3′-end of exon 1 resulting in a putatively non-functional allele. Alignment of the amino acid sequence showed strong homology throughout the central fragments of the gene but broad variation in the transit peptides. All putative functional alleles maintained the reported active sites for glycogen synthesis, though with variations in other highly conserved areas of the gene. These variations within the wild relatives of cultivated cereals may provide novel sources of genetic diversity for future cereal improvement programs.     

Magnetic resonance imaging and analyses of tempering processes in rice kernels

This research involved a magnetic resonance imaging (MRI) technique that was applied to examine water distribution and migration in single rice kernels during the tempering process. The imaging experiments were performed in a Bruker 9.4T MRI system. Three-dimensional spin-echo (SE) imaging sequences were optimized by adjusting the scanning parameters of echo time (TE) and repetition time (TR) to obtain images with maximum contrast. The MR images showed that the moisture distribution in the rice kernel is non-uniform and compartmental. The embryo region exhibited much higher MR signal intensity than the starchy endosperm portion. The tempering process was analyzed with spatial-temporal signal intensities of the endosperm following the drying process of the rice kernel. The transient change of the signal intensities in the endosperm was well fitted with a double exponential function suggesting that both convection and diffusion contributed to the reduction of the moisture gradient within the rice kernel during tempering. This hypothesis was further supported by the experimental data of the insulated rice kernel whose convective mass transfer was excluded. The experimental results revealed that MR imaging of rice kernels could be used as an efficient tool to examine the mechanisms of moisture migration within cereal grains.     

粳型杂交稻稻米外观品质性状的遗传效应研究

 以宁67A等4个粳型不育系与K1722等9个粳型恢复系进行不完全双列杂交，采用禾谷类作物胚乳品质性状的遗传模型及其分析方法，对粳型杂交稻稻米外观品质性状进行了遗传研究。结果表明，稻米的糙米长、糙米长宽比、糙米长厚比主要受母体加性效应控制，而透明度以母体加性效应和种子直接加性效应为主；垩白率、垩白度主要受种子直接加性和母体加性效应所控制，以种子直接加性效应为主。多数性状的种子直接遗传率、细胞质遗传率和母体遗传率均达显著或极显著水平，其中糙米长、糙米长宽比、糙米长厚比、透明度以母体遗传率为主，垩白率、垩白度以种子直接遗传率为主。另外，根据性状的遗传效应预测值对各亲本的育种利用价值作了评价     

Cloning,expression and functional analysis of HMW glutenin subunit 1By8 gene from Italy pasta wheat (Triticum turgidum L. ssp. durum)

Cloning and functional analysis of high molecular weight wheat glutenin subunit (HMW-GS) 1By8 from Italy durum cultivar Simeto was carried out in this study. All HMW-GS from Simeto were separated and characterized by appropriate electrophoresis methods, reversed-phased high performance liquid chromatography (RP-HPLC) and mass spectrometry (MS). The complete gene encoding 1By8 subunit was amplified by allele-specific PCR primers, including an upstream sequence of 857 bp and an open reading frame (ORF) of 2166 bp encoding a mature protein of 720 amino acid residues. The promoter sequence, containing -300 element (cereal glutenin gene control element) and enhancer was highly conserved among HMW-GS genes. Comparison with the sequence of subunit 1By9 from bread wheat demonstrated 99% identity with the main difference being that the 1By8 subunit possesses an additional insertion of 15 amino acid residues (QYPASQQQPA QGQQG) at position 342 and two residue substitutions at position 78 (leucine/proline) and 442 (arginine/glutamine). The molecular weight differences between MALDI-TOF-MS and deduced amino acid sequence of the coding gene revealed the possibility of some kinds of post-translational modifications present in 1By8 subunit. The protein subunit expressed in Escherichia coli showed a very similar mobility to the endogenous 1By8 of Simeto on SDS-PAGE. The function of the isolated protein on wheat processing quality was determined by 10 g Mixgraph analysis. Results demonstrated that addition of y-type HMW glutenin subunits into the base flour had significant positive effects on main mixing parameters and significant difference in effects were observed among different y-type subunits.