Endosperm Texture in Wheat

One of the fundamental means of classifying wheat is through its endosperm texture. It impacts significantly on the milling process affecting among other things flour particle size and milling yield. Hardness in wheat is largely controlled by genetic factors but it can be affected by the environment and factors such as moisture, lipid, and pentosan content. The principal genetic locus controlling endosperm texture in wheat, Ha, is located on the chromosome 5D. At this locus several genes, notably the puroindolines, have been identified. Puroindolines are the major components of the 15 kDa protein band associated with starch granules that is more abundant in soft wheats than in hard. Recently the puroindolines have been shown to enhance grain hardness in rice. In this review we discuss the structure of hard and soft wheat endosperm with particular emphasis on when differences in endosperm texture can be detected in the developing seed. The role of the environment and other factors that may affect the endosperm texture is also examined together with the role of the puroindoline genes at theHa locus. Finally, we compare endosperm hardness in wheat and in barley.     

Support of the endosperm balance number hypothesis utilizing some tuber-bearingSolanum species

The normal development of the endosperm appears to depend on a ratio of two female genomes to one male genome in most angiosperms. However, successful crosses between some tuber-bearingSolarium species do not conform to this ratio. An endosperm balance number (EBN) hypothesis has been proposed to reconcile the two female genomes: one male genome ratio proposal and the anomalous crossing behavior of some species. Crosses performed to test the EBN hypothesis are reported in this paper. The results support the hypothesis and demonstrate its usefulness in predicting the success or failure of a cross and the ploidy of the offspring. A format for conducting and reporting crossing experiments is proposed that facilitates the comparison of results of different experiments.     

Sorghum endosperm texture – A review

A review of literature on endosperm texture determination and its relationship with milling performance is presented. Methods for measuring sorghum endosperm texture as abrasive, pearling and wet milling are reported. This review describes some indirect methods: time to grind by the Brabender microhardness tester (BHMT), resistance to grinding by the Stenvert hardness tester (SHT), two methods for determination of average particle size: particle size index (PSI) and near-infrared (NIR) reflectance and others based on density differences between the floury and vitreous part of the endosperm.     

Pearling Quality of Canadian Barley Varieties and their Potential Use as Rice Extenders*

Barley can be used as an extender of rice to increase the nutritive value of the end-product. Specific quality barley is required if the processed barley is to resemble cooked white rice in colour and shape. The barley must pearl and split without the production of broken kernels or fines and yet produce desired end use quality. Barley endosperm texture and colour are key to determining these processing characteristics. Testing of Canadian barley types indicated the waxy type was most appropriate for pearling and processing as rice extender. It had a firm endosperm texture that was not steely and yet processed into a white product with few broken grains. Covered barley was of better quality than hull-less, as the former generally had fewer steely kernels as well as firmer endosperm texture. Differences observed between two- and six-rowed type were related to grain size and could be overcome by proper adjustments to processing conditions. Growing conditions affected kernel size and barley protein contents but to a lesser extent than barley type. L* brightness values, Particle Size Index and kernel size were found to be important predictors of barley quality for pearling and as rice extender.     

稻米支链淀粉结构的研究进展

随着我国国民经济的发展和人民生活水平的提高,人们对稻米品质的要求越来越高,在丰产的基础上还要求有较好的口感。支链淀粉是稻米淀粉的主要成分,其结构对食味品质有重要的影响。本文介绍了稻米支链淀粉结构的测定方法,籼粳稻支链淀粉结构的差异、遗传机制,支链淀粉超长链部分的合成调控以及支链淀粉的结构与理化特性和食味品质关系等方面的研究现状,认为今后有必要改进、完善和规范现有的支链淀粉结构测定方法,进一步研究籼粳稻杂交后代支链淀粉结构的差异,明确支链淀粉结构与亚种分化之间的关系,与此同时对支链淀粉结构与稻米食味品质之间的关系进行深入研究,以期为我国水稻生产及稻米品质改良提供理论指导。     

Investigation by Confocal Raman Microspectroscopy of the Molecular Factors Responsible for Grain Cohesion in theTriticum aestivum Bread Wheat. Role of the Cell Walls in the Starchy Endosperm

Confocal Raman microspectroscopy has previously been employed to investigate the protein content and composition of the starchy endosperm of the wheat grain. With the same objective, that is to determine the molecular basis of grain cohesion and more specifically of kernel hardness, the contribution of endosperm cell walls in the kernel structure and cohesion was explored. The technique showed that endosperm cell walls consist not only of arabinoxylan chains with ramifications of ferulic esters, but also of others components such as proteins and lipids that could play some role in the mechanical properties of the endosperm cell walls. A new model of interaction between ferulic ramifications and a phospholipid component was proposed. The investigation of cell wall composition at successive stages of grain development revealed a decrease in the protein to arabinoxylan ratio and simultaneously an increase of the ferulic acid to arabinoxylan ratio that could be associated with a strengthening of the cell wall structure. The study confirms the effectiveness of confocal Raman microspectroscopy to approach the structure of wheat grain at the micrometer scale and to identify specific molecular factors responsible for grain cohesion and involved in the fracture modes generated during the milling process.     

Structural and Histochemical Characterization of Developing Rice Caryopsis

The development of pericarp, seed coat, starchy endosperm and aleurone of the rice caryopsis was investigated, histochemically and structurally, from the time of flowering to maturity. The results showed that during its growth, the maximum length of the caryopsis was attained first, followed by width and then thickness. Histochemical examination of the caryopsis showed that starch was mainly accumulated in the endosperm, but the endosperm showed no metabolic activity, while embryo and pericarp contained a few starch grains, and embryo and aleurone were strongly active. Aleuronic cells contained many aleurone grains and spherosomes, and aleurone in the dorsal region developed earlier and contained more layers of cells. Amyloplasts in endosperm contained many starch granules and were spherical at early stages but polyhedric at late stages. The protein bodies appeared later than amyloplasts, and the number of protein bodies in subaleurone was greater than those in the starchy endosperm. The white-belly portion of endosperm might be relative to the status of amyloplast development.     

The reproductive biology of the potato and its implication for breeding

Summary Haploidy, 2n gametes, synaptic mutants, stylar barriers, endosperm barriers. Endosperm Balance Number (EBN) and its relationship to 2n gametes, stylar barriers and disomic genetics are a part of the reproductive biology of potato. Also all are tools for isolation and preservation of a species identity. Haploidy and 2n gametes allow for interploidy gene transfer. Parallel spindles and synaptic mutants permit the transfer of entire parental genomes intact and are powerful tools in potato breeding. Stylar barriers provide a mechanism for interspecific isolation via unilateral incompatibility. Incongruity has also been invoked. Endosperm barriers have been discussed in terms of EBN which requires a 2 maternal:1 paternal ratio in the endosperm for successful seed development. Genetic models suggesting three unlinked genes in a threshold-like system and a two gene system have been proposed. A relationship may exist between EBN and stylar barriers. The use and manipulation of 2n gametes, stylar barriers and EBN have been used effectively in germplasm transfer from species to cultivated potato. Note: This paper is dedicated to Dr S.J. Peloquin, Emeritus Professor, Department of Horticulture, University of Wisconsin-Madison, a mentor, friend and colleague, in recognition of the enormous contributions he has made to this area and for his enthusiasm for and stimulation of others to an awareness of the importance of its application to plant improvement. Cooperative investigation of the Vegetable Crops Research Unit, United States Department of Agriculture, Agricultural Research Service and the Wisconsin Agricultural Experiment Station.     

Cenchrus biflorus Roxb. (Indian sandbur), a blessing or curse in arid ecosystems: a review

Although a widely used forage plant in arid areas, Cenchrus biflorus is viewed by many scientists as an invasive weed that has a serious negative impact on agriculture and biodiversity in arid and semi‐arid environments. It has risen from insignificance as a forage and famine cereal crop to its recent status as one of the most economically destructive weeds in many regions of the world. Numerous features like high nutritional value, prolific seed production, tolerance to high temperature and prolonged drought conditions contributed greatly towards its success as a potential forage species in arid environments. But, evidence from agriculturalists shows that it is a destructive invader which disrupts cultural practices and reduces natural biodiversity. Unfortunately, limited knowledge is available about its ecology and management in natural habitats and agro‐ecosystems. In this paper, we provide a comprehensive review of its ecology, biology, agricultural impact, management and utilization. This review also provides future directions for research on C. biflorus in arid environments.     

The low-molecular-weight glutenin subunits of wheat gluten

Low-molecular-weight glutenin subunits (LMW-GS) are polymeric protein components of wheat endosperm and like all seed storage proteins, are digested to provide nutrients for the embryo during seed germination and seedling growth. Due to their structural characteristics, they exhibit features important for the technological properties of wheat flour. Their ability to form inter-molecular disulphide bonds with each other and/or with high-molecular-weight glutenin subunits (HMW-GS), is important for the formation of the glutenin polymers, which are among the biggest macromolecules present in nature, and determine the processing properties of wheat dough. Explanation of the structural basis for these correlations continues to intrigue researchers and, while earlier emphasis had been on HMW-GS, considerable attention is now being focused on the LMW-GS.LMW-GS are a highly polymorphic protein complex, including proteins with gliadin-type sequences. Difficulty in separating single components, arising from the complexity of the group, has limited the characterisation of the individual proteins and the establishment of clear-cut relationships with quality parameters.Here we review results concerning different aspects of LMW-GS, including their structural characteristics, genetic control, and relationships with quality parameters. In addition, we emphasise the distinction between the components with sequences unique to the LMW-GS fraction and those behaving like glutenin subunits (incorporated into polymers), but with sequences corresponding to gliadins.     

Relationship between the corneous and floury endosperm content and the popped sorghum quality

Popcorn is a healthy snack suggested by nutritionists. However, some countries in Europe, Asia, and South America have evaluated the use of sorghum as a popped cereal. Therefore, this study aims to evaluate the content of corneous and floury endosperm of sorghum and its influence in the popped sorghum quality. Five red varieties and three white varieties were evaluated. The physical and microstructural characteristics of the raw varieties were evaluated. The correlation matrix showed that physical properties such as the pericarp thickness, the hectoliter weight, and the type of endosperm are crucial to obtain popped sorghum. A high percentage of corneous endosperm and the size distribution of starch granules in the floury endosperm determine the popping ability of sorghum. The analysis of the principal components showed that the Paloma variety was the most suitable to obtain popped sorghum.     

Quality Protein Maize: Overcoming the Hurdles

SUMMARY

Quality Protein Maize (QPM), a nutritionally enhanced maize, was developed by researchers from CIMMYT using too genetic systems–opaque-2 and genetic modifiers. The use of these two genetic systems overcame the highly complex problems that were inherent in the original soft endosperm opaques. This review describes the ever-evolving breeding options and strategies for the development of QPM with examples from the CIMMYT maize program, where much of the research and practical breeding work has been done. The soft endosperm opaque-2 materials developed earlier had poor agronomic performances and lacked producer and consumer acceptance. To overcome these constraints, subsequent research explored various options, with and without high lysine mutants. Like other institutions, CIMMYT researchers tried and critically examined the merits and demerits of different strategies. Of all the strategies available, the selection for modified kernels in which CIMMYT scientists had gained information, experience, and confidence seemed viable. To implement this strategy, modified opaque-2 donor stocks were built and were subsequently used for expanding the QPM developmental efforts. A large volume of QPM germplasm was developed using different breeding options, which were later merged and reorganized into a fixed number of pools and populations to permit working in homozygous opaque-2 genetic backgrounds. The development of QPM hybrids was the next turning point in the mid-80s. During the QPM developmental process, serious problems inherent in the opaques were circumvented and since then, rapid progress has been made. There is a renewed interest in QPM and several countries have recently released QPM varieties and hybrids. To further accelerate the QPM developmental process, to enhance its popularity amongst nations and its farmers, and to meet future challenges, innovative ideas and the tools of biotechnology will be needed.     

椰子水贮藏保鲜和加工技术研究进展

椰子水是一种古老的热带饮料,以其天然、纯净、营养和健康的特性受到越来越多的消费者喜爱,并引起了 众多饮料生产商们的注意。由于椰子一旦被打开裸露接触到空气中时,椰子水的化学成分和风味会发生很大变化,造 成了收集、贮藏和加工困难。因此,多年来限制了其向商业化应用。研究表明,对采后椰子水进行适当处理,可以有 效改善成品椰子水的货架期。目前,对于椰子水加工,热处理联合化学添加技术已经成熟并应用在工业生产上,但一 些新技术如膜过滤技术、超高压技术和高密度二氧化碳技术等还没有被大规模应用。无论哪一种加工技术,都不可避 免的改变椰子水的口感、风味和色泽,寻找和掌握一种既能保持天然的口感、风味和色泽,又能有较为理想货架期的 椰子水工业化生产技术是当务之急。然而,全球对椰子水方面的研究仍然比较少,主要集中在对整个椰子鲜果的保鲜 和椰子水的加工研究上。本文将主要综述至今文献报道相关椰子水贮藏保鲜和加工技术方面的研究情况。     

Effects of Popping on the Endosperm Cell Walls of Sorghum and Maize

The structure of the vitreous endosperm of raw and popped grains of popcorn maize and sorghum has been examined by light and scanning electron microscopy. In both cereals, popping produces everted grains consisting of expanded endosperm foam attached to the pericarp and embryo tissue. As previously reported, each bubble of the foam is formed from an individual starch granule inflated by internal steam pressure. Large fissures may contribute significantly to the expansion of the endosperm foam. The cell walls of the vitreous endosperm of both cereals are shattered into small fragments, which separate slightly as the cell contents expand during popping. Despite this, the endosperm cells retain their polygonal outline. Intact cell walls of raw endosperm, wall fragments from popped endosperm foam, and fragments isolated after treatment of the foam withalpha -amylase, were visualised through the autofluorescence of their ferulic acid content. The in vitro digestibility of popped sorghum was unchanged compared to raw sorghum, whereas that of wet-cooked sorghum was greatly reduced. It is suggested that popping-induced wall fragmentation improves the accessibility of the protein and starch reserves of the endosperm to digestive enzymes.     

人工控温条件下稻米垩白形成变化及胚乳扫描结构观察

 利用人工气候箱设高温（33℃）和适温（23℃）2个不同的温度处理,对2个不同垩白类型品种西农8116和广二矮104抽穗后稻米垩白的变化动态进行了研究,并通过对不同温度下稻米胚乳内部淀粉体形态、大小、发育程度、排列结构的扫描电镜观察,分析了稻米垩白形成变化与胚乳内部淀粉体结构特征的关系,结果表明,水稻灌浆结实期稻米垩白形成的变化过程主要是在抽穗5 d到15~20 d的这一时期,其余时段垩白度的变化幅度不大;高温（33℃）与适温（23℃）处理相比,以抽穗后10~20 d间的变化差别最为明显;胚乳淀粉体表现为“裸露型”还是“非裸露型”,主要与胚乳细胞内部淀粉粒发育程度有关,而与品种本身的垩白类型特征无必然联系     

中国胯姬小蜂属(膜翅目:姬小蜂科)——新记录种

海南桉树林地受桉树枝瘿姬小蜂(Leptocybe invasa FisherLa Salle)为害较重,为了有效防治桉树枝瘿姬小蜂,于2014年12月~2015年7月在海南三亚、东方、儋州、临高等地开展了桉树枝瘿姬小蜂寄生性天敌资源的调查。在为期8个月的调查期间,收集到了大量桉树枝瘿姬小蜂及其寄生蜂,并对其生物学进行了观察。其中一种寄生蜂,孟氏胯姬小蜂(Quadrastichus mendeli KimLa Salle),为国内首次报道,确定为中国新纪录种。本研究对孟氏胯姬小蜂进行了描述,同时对其生物学进行了补充。     

The Superworm,Zophobas morio (Coleoptera:Tenebrionidae): A ‘Sleeping Giant’ in Nutrient Sources

The aim of this review is to compile up-to-date information on the superworm, Zophobas morio (F.), regarding its biology and ecology, but also its further potential for use as a nutrient source for food and feed. We illustrate certain basic characteristics of the morphology and bio-ecology of this species, which is marginally considered as a ‘pest’ in durable amylaceous commodities. More recent data show that Z. morio can be a valuable nutrient and antimicrobial source that could be utilized further in insect-based feed and food production. The inclusion of this species in aquafeed has provided promising results in a wide range of feeding trials, both in terms of fish development and health. Additional data illustrate its potential for use in poultry, indicating that this species provides comparable results with those of other insect species that are used in feed. Moreover, Z. morio can be a viable waste management agent. This review aims to summarize the available data and underline data gaps for future research, toward the potential of the utilization of Z. morio for human food and animal feed. Based on the data presented, Z. morio appears to be a well-promising insect-based protein source, which potential still remains to be unfold.     

多效唑对晋薯7号马铃薯的调控作用

在马铃薯初花期喷施植物生长调节剂多效唑,试验结果表明:多效唑显著抑制植株的高度,单株结薯数下降,大薯率上升,当每667m2喷施多效唑75g,浓度在2.5g.L-1时是本试验中提高产量的最佳浓度,干物质和淀粉均有明显的提高。说明喷施多效唑具有控上促下的作用,从而有利于提高产量和品质。     

胚乳蛋白质对稻米品质影响的研究进展

蛋白质是稻米胚乳中仅次于淀粉的第二大贮藏物质，蛋白质含量、组分、形态以及分布特征对稻米品质均具有重要影响。本文梳理了胚乳蛋白质与稻米外观品质、加工品质、营养品质和蒸煮食味品质关系的研究进展，并对未来研究方向提出了展望。结果可为进一步解析胚乳蛋白质在稻米品质形成中的作用和稻米品质改良提供参考。