Comparing the interactive effects of water and nitrogen on durum wheat and barley grown in a Mediterranean environment

The understanding of the interactive effect of water and N availability, associated with the ability of crops to efficiently use these resources, is a crucial issue for stabilizing cereal production in Mediterranean areas. A 3-year side by side experiment on durum wheat and barley, under different water regimes and nitrogen levels, was carried out in a typical Mediterranean environment of Southern Italy, to identify the outstanding features of these species that contribute to enhanced grain yield and improved water and nitrogen use efficiency.     

Control of Gene Expression for the Genetic Engineering of Cereal Quality

The recent success of techniques for the direct transfer of individual genes to cereal species suggests that specific modifications to grain end-use properties will be achievable in the near future. The suitability of direct gene transfer to the problem, the choice of the promoter and transformation strategy need to be considered before attempting such modifications. This review discusses these questions with reference to current knowledge of seed-specific and, in particular, endosperm-specific and abscisic acid-responsive gene promoters. This perspective is of special importance in attempts to engineer cereal proteins.     

基于压痕加载曲线的谷物籽粒物理特性试验与仿真

利用CMT8102微机控制材料试验机对豌豆、玉米、小麦、绿豆进行了加载-卸载试验,得到了4种谷物籽粒的载荷-压痕深度曲线.在谷物籽粒弹塑性力学性能研究中引入Venkatesh反向运算法则,计算出了4种谷物籽粒的弹性模量、屈服应力、硬化指数、接触刚度、最大接触面积等力学特性参数;把得到的弹性模量、屈服应力理论值添加到Abaqus的材料属性模块,对4种谷物籽粒的压入过程进行模拟仿真,得到了压痕形貌图和仿真曲线.仿真和试验曲线拟合结果说明了仿真的有效性,并且验证了Venkatesh反向运算法则在谷物籽粒材料特性研究中的准确性;压痕形貌图说明谷物籽粒具有弹塑性.研究还表明谷物籽粒硬度与应变硬化指数、最大等效接触应力、残余应力和屈服应力呈正比,与应力集中区域呈反比.     

Improving cereal grain carbohydrates for diet and health

Starch and cell wall polysaccharides (dietary fibre) of cereal grains contribute to the health benefits associated with the consumption of whole grain cereal products, including reduced risk of obesity, type 2 diabetes, cardiovascular disease and colorectal cancer. The physiological bases for these effects are reviewed in relation to the structures and physical properties of the polysaccharides and their behaviour (including digestion and fermentation) in the gastro-intestinal tract. Strategies for modifying the content and composition of grain polysaccharides to increase their health benefits are discussed, including exploiting natural variation and using mutagenesis and transgenesis to generate further variation. These studies will facilitate the development of new types of cereals and cereal products to face the major health challenges of the 21st century.     

Development of analytical systems based on real-time PCR for Triticum species-specific detection and quantitation of bread wheat contamination in semolina and pasta

The cereal composition of specific foods is always a key factor in the quality and safety of the final product. It is important to introduce new control methods for certain special foods, such as those for coeliac consumers, where the contamination of different cereal species must be accurately determined. Moreover, pasta made from durum wheat is considered superior in several qualitative aspects to that manufactured with bread wheat or a mixture of the two species. This work has been directed toward the development of analytical systems for the qualitative and quantitative detection of specific cereals in food. More specifically, the primary aim of this work has been to develop analytical tools based on end-point and real-time PCR to detect the presence of Triticum species in flour and food. Furthermore, qualitative and quantitative PCR-based methods are proposed to detect hexaploid wheat adulteration in pasta.     

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.     

Heritability and quantitative trait loci of composition and structural characteristics in sorghum grain

Breeding efforts in cereal crops directed toward developing or improving end-use products of grain require assessment of existing phenotypic variance and an understanding of the genetic control of grain quality traits. To this end, a grain sorghum [Sorghum bicolor (L.) Moench] mapping population consisting of 113 F_2:7 recombinant inbred lines (RILs) derived from a cross between Sureño and RTx430 was evaluated in multiple environments for grain composition (fat, fiber, protein, starch) using near-infrared reflectance spectroscopy (NIRS), and size estimates of grain parts (embryo, vitreous endosperm, floury endosperm, kernel area) using an image-based phenotyping software system. Estimates of broad-sense heritability of grain compositional traits ranged from 0.11 to 0.90, whereas those of grain size ranged from 0.16 to 0.72. Composite interval mapping (CIM) was applied to a single nucleotide polymorphism (SNP)-based linkage map to identify marker-trait associations, and through these efforts, a total of 37 quantitative trait loci (QTL) for grain quality were identified across environments. Each QTL explained between 7 and 23% of the phenotypic variation for a given grain trait. Three of the five QTL that colocalized were for traits with significant negative correlation, which included grain protein content that was negatively correlated with grain starch content. In addition, several traits that were positively correlated (e.g. fat and fiber content) also revealed colocalized QTL. Finally, we compared the present study with previous studies identifying grain composition trait loci in an effort to identify genomic regions controlling grain traits across a diversity of environments and sorghum genotypes.     

Increased understanding of the cereal phytase complement for better mineral bio-availability and resource management

The present paper summarizes the current state of knowledge on cereal phytase that are particular relevant for improving mineral and phosphate bio-availability. Phytases can initiate the hydrolysis of phytate, the main storage form of phosphate in cereals and the major anti-nutritional factor for the bio-availability of micronutrients in human nutrition. The composition and levels of mature grain phytase activity (MGPA) in cereals is of central importance for efficient phytate hydrolysis. The MGPA varies considerably between species. Substantial activity is present in Triticeae tribe cereals like wheat, barley and rye whereas non-Triticeae cereals such as maize and rice have very little MGPA. Recent studies have determined the evolutionary relationships of phytases in Triticeae and non-Triticeae and highlighted the importance of the purple acid phosphatase phytases (PAPhys). In the Triticeae, PAPhys are synthesized during grain development (PAPhy_a) and during germination (PAPhy_b). In non-Triticeae species, only PAPhys that are mainly synthesized during germination were identified. The new knowledge provides new opportunities for modulating the MGPA in Triticeae cereals but also indicates that nutritionally relevant levels of MGPA are unlikely to be achieved in non-Triticeae by conventional breeding. Increasing MGPA in barley via cisgenesis is discussed.     

The influence of nitrogen fertilizer on the yield and combustion quality of whole grain crops for solid fuel use

Whole grain crops can be suitable for the production of solid biofuels because they have a high biomass yield and can be harvested with a low water concentration. The concentrations of water, ash, nitrogen (N), sulphur (S), chlorine (Cl) and potassium (K) in solid biofuels should be as low as possible and calcium (Ca) concentrations high to avoid technical problems and environmentally harmful emissions during the combustion process. Since N fertilization can negatively influence the combustion quality of biomass, a conflict between yield and quality aims can arise. The aim of this study is to investigate the influence of the dosage of N fertilization on the yield and quality of the whole crop biomass of triticale, rye and wheat. In 1996 and 1997, field trials with winter triticale, winter rye and winter wheat were conducted at three locations in South-West Germany. N fertilizer doses were varied from 0 to 70 and 140 kg N ha⁻¹ a⁻¹. All N doses were applied between March and May. The whole crop biomass was harvested. The water concentrations and concentrations of ash, N, K, Cl and Ca in straw and grain were measured. A dose of 70 kg N significantly increased the yield of all cereal species, but yield increases at 140 kg N were not always significant when compared with 70 kg N. At 70 kg N the energy yields reached 137–249 GJ ha⁻¹, for wheat, 142–263 GJ ha⁻¹ for rye and 182–250 GJ ha⁻¹ for triticale. The water concentration of the biomass, mainly of the straw, was significantly increased by N fertilization when the harvest was performed early at comparatively high water concentrations. For all cereal species a significant increase of N concentrations, especially in the grain, was measured at increased N fertilizer levels. The K concentrations of the straw and the Ca concentrations of straw and grain of all cereal species were also increased by N fertilization. N fertilization had little or no effect on the ash and Cl concentrations, which slightly decreased with increased N fertilization. N fertilization can, therefore, be used as a tool to influence the concentrations of N and K in the biomass. When combining yield and quality aims, 70–100 kg ha⁻¹ a⁻¹ N fertilizer was the best dosage for the whole grain crops at the southwestern German locations tested here.     

Screen of Genes Linked to High-Sugar Content in Stems by Comparative Genomics

One of the great advantages of the fully sequenced rice genome is to serve as a reference for other cereal genomes in particular for identifying genes linked to unique traits. A trait of great interest is reduced lignocellulose in the stem of related species in favor of fermentable sugars as a source of biofuels. While sugarcane is one of the most efficient biofuel crops, little is known about the underlying gene repertoire involved in it. Here, we take advantage of the natural variation of sweet and grain sorghum to uncover genes that are conserved in rice, sorghum, and sugarcane but differently expressed in sweet versus grain sorghum by using a microarray platform and the syntenous alignment of rice and sorghum genomic regions containing these genes. Indeed, enzymes involved in carbohydrate accumulation and those that reduce lignocellulose can be identified.     

Niacin status of humans as affected by eating decorticated and whole-ground sorghum (Sorghum Gramineae) grain,ready-to-eat breakfast cereals

Niacin utilization to humans from whole grain ground sorghum flour and decorticated grain ground sorghum flour was studied. During two, randomly-arranged experimental periods of 14 days each, the 10 healthy adult subjects ate constant, laboratory controlled diets which included 28 g per day of either a ready-to-eat cereal prepared from whole-ground-sorghum flour or one prepared from decorticated (polished) sorghum flour. All subjects received both experimental treatments, made complete collections of urine and stools, and gave fasting blood samples at the ends of both experimental periods. Although the whole ground cereal contained higher amounts of niacin than did the decorticated cereal, urinary losses of N-methylnicotinamine were higher when the decorticated cereal was fed than when the whole ground cereal was used. Blood serum levels of nicotinamide and N-nicotinamide were higher when the whole ground cereal was fed than the feeding of the decorticated cereal was given. Therefore, it appears that the niacin of whole ground sorghum is absorbed but then the need for niacin is either increased or its urinary excretion is inhibited.Published as University of Nebraska Division of Agriculture Research Journal Series No. 9494. Supported by Nebraska Agriculture Research Division Project 91-031 and U.S.D.A. C.S.R.S. Regional Research Project No. W-143.     

Effect of supplementation with grain, hay or straw on the performance of weaner Merino sheep grazing old man (Atriplex nummularia) or river (Atriplex amnicola) saltbush

Old man saltbush ( Atriplex nummularia ) and river saltbush ( A. amnicola ) are widely used in commercial grazing systems on saline land in south-western Australia. Three hypotheses were tested during a 3-year study aimed at understanding the performance of weaner Merino sheep grazing saltbush-based pastures. The first hypothesis, that young Merino sheep grazing river saltbush would be better able to maintain live weight, body condition and would grow more wool than sheep grazing old man saltbush, was not supported by the data. Across the 3 years of the study, sheep grazing old man saltbush lost significantly less live weight and grew more wool (proportionately 0·06) than sheep grazing river saltbush. Differences in animal performance were considered to be associated with differences between the plant species in in vitro digestibility, concentrations of fibre, sulphur and crude protein in the herbage and the architecture of the Atriplex plants. The second and third hypotheses concerned supplementation strategies for sheep grazing saltbush. Three supplements were offered, namely barley grain, cereal straw or cereal hay, at a rate that approximated to one-third of the daily metabolizable energy requirements for maintenance of live weight. The performance of the sheep was higher when the grain supplement was offered but there was no effect of feeding roughage supplements compared to no supplementation. The findings suggested that the practice of feeding saltbush with adjacent crop stubbles is unlikely to be beneficial once any fallen grain has been consumed.     

Chemical imaging: the distribution of ions and molecules in developing and mature wheat grain

The ability to combine topographical and in situ chemical analysis of individual cereal grains, without recourse to fractionation, offers an opportunity to determine the distribution of functionally- and nutritionally-important components. Three such technologies are reviewed, including immunolocation using monoclonal antibodies specific for different types of wheat prolamins, secondary ion mass spectroscopy (SIMS) to detect the presence of inorganic elements such as sodium and sulphur, and infrared (including Raman and Fourier-transform infrared [FT-IR]) microspectroscopy to determine the distribution of biopolymers across the grain. Immunolabelling has shown that the distribution of prolamin proteins changes across the endosperm, with the outer endosperm containing a much greater proportion of prolamins than the inner endosperm. SIMS has shown, for the first time, the presence of Na⁺ in the phytin granules and that sulphur is enriched at the boundary between the starch granules and the protein matrix. Raman microspectroscopy has been used to investigate the distribution of proteins and the phenolic compound, ferulic acid, across the grain, whilst FT-IR has been used to define the microheterogeneity of arabinoxylans in endosperm cell walls. These methods highlight how in situ analysis can yield new insights into grain composition and how this may be altered by environmental conditions during grain development.     

The Endosperm Morphology of Rice and its Wild Relatives as Observed by Scanning Electron Microscopy

While cultivated rice, Oryza sativa, is arguably the world’s most important cereal crop, there is little comparative morphological information available for the grain of rice wild relatives. In this study, the endosperm of 16 rice wild relatives were compared to O. sativa subspecies indica and O. sativa subspecies japonica using scanning electron microscopy. Although the aleurone, starch granules, protein bodies and endosperm cell shapes of the cultivated and non-cultivated species were similar, several differences were observed. The starch granules of some wild species had internal channels that have not been reported in cultivated rice. Oryza longiglumis, Microlaena stipoides and Potamophila parviflora, had an aleurone that was only one-cell thick in contrast to the multiple cell layers observed in the aleurone of the remaining Oryza species. The similarity of the endosperm morphology of undomesticated species with cultivated rice suggests that some wild species may have similar functional properties. Obtaining a better understanding of the wild rice species grain ultrastructure will assist in identifying potential opportunities for development of these wild species as new cultivated crops or for their inclusion in plant improvement programmes.     

Molecular genetic approaches to increasing mineral availability and vitamin content of cereals

The present paper summarizes the current state of knowledge on molecular genetic approaches to increasing iron and zinc availability and vitamin content in cereals. We have also attempted to integrate the scientific issues into the wider context of human nutrition. In the cereal grain, iron and zinc are preferentially stored together with phytate in membrane-enclosed globoids in the protein storage vacuole (PSV) found in the aleurone and the embryo scutellum. The PSV is accordingly central for understanding mineral deposition during grain filling and mobilization of minerals during germination. Recent studies in Arabidopsis have led to the first identification of iron and zinc transporters of the PSV and further illustrate some of the dynamics associated with mineral and phytate transport and deposition into the vacuole. This provides new opportunities for modulating iron and zinc deposition in the cereal grain. Current strategies towards increasing the iron content of the endosperm are largely based on the expression of legume ferritin genes in an endosperm-specific manner. However, it is apparent that this approach, at least in rice, only allows a two- to three-fold increase in the iron content of the grain due to exhaustion of the iron stores in leaves. Further increases thus have to rely on additional uptake and transport of iron from the root. Phytate is generally considered to be the single most important anti-nutritional factor for iron and zinc availability. In the current paper we summarize attempts to increase phytase activity in the grain by transformation and evaluate the potential of this approach as well as the reduction of phytate biosynthesis for improving the bioavailability of iron and zinc. Vitamins constitute the second important group of micronutrients in grain and we discuss current efforts to increase the amounts of provitamin A, vitamin C and vitamin E.     

Microdochium nivale and Microdochium majus in seed samples of Danish small grain cereals

Microdochium nivale and Microdochium majus are two of fungal species found in the Fusarium Head Blight (FHB) complex infecting small grain cereals. Quantitative real-time PCR assays were designed to separate the two Microdochium species based on the translation elongation factor 1α gene (TEF-1α) and used to analyse a total of 374 seed samples of wheat, barley, triticale, rye and oat sampled from farmers' fields across Denmark from 2003 to 2007. Both fungal species were detected in the five cereal species but M. majus showed a higher prevalence compared to M. nivale in most years in all cereal species except rye, in which M. nivale represented a larger proportion of the biomass and was more prevalent than M. majus in some samples. Historical samples of wheat and barley from 1957 to 2000 similarly showed a strong prevalence of M. majus over M. nivale indicating that M. majus has been the main prevalent Microdochium species in Danish cereals for at least 50 years. PCA analysis of the two quantified Microdochium species in wheat, barley and triticale samples generally showed co-existence of M. majus and M. nivale in all three cereal species. Strobilurin resistance in M. nivale/majus was analysed in selected wheat samples from 2003 to 2007, selected barley samples from 2007 as well as in historical samples from 1957 to 2000 using CAPS analysis to detect the G143A substitution. The results confirm strobilurin resistance from 2003 in the Microdochium populations of wheat and also confirmed resistance in barley for the first time. The presence of strobilurin resistance should be considered in future fungicide control strategies.     

Fusarium genetic traceability: Role for mycotoxin control in small grain cereals agro-food chains

Risks associated with mycotoxin contamination of cereals, that are included in the ten major staple foods and greatly contribute to the dietary energy intake, are of worldwide relevance. In small grain cereals, mycotoxins are produced by fungi such as Aspergillus, Penicillium, Alternaria and Fusarium that colonize the plant in the field and can grow during the post-harvest period, producing several classes of mycotoxins. The identification of mycotoxigenic fungal species and strains is essential for developing effective strategies for control. For this purpose, genetic traceability has proved to be a valuable tool that can be applied along the whole production chain, starting in the field for early diagnosis of FHB (Fusarium Head Blight) disease to the final processing steps, such as malting or pasta making. In this paper, DNA-based analytical tools that are currently available for the identification and quantification of mycotoxigenic fungal species and strains are reviewed, with particular emphasis on Fusarium, and their possible applications in mycotoxin control in small grain cereal chains are discussed.     

Minor components and wheat quality: Perspectives on climate changes

Minor compounds of cereal grains such as lipids and cell wall polysaccharides play an important role in their milling properties, their transformation into baked cereal products and their nutritional properties. These effects are mainly due to their interactive properties, such as their ability to absorb large amounts of water for polysaccharides or to interact with starch polymers and proteins for lipids. Environmental stress induced by climate change and regulations for environmentally friendly agriculture can interfere with the biosynthesis of these minor grain compounds as well as the main compounds starch and protein. Indeed, the metabolic networks of all components of the endosperm of grains are closely associated. Therefore, in the context of climate change and agricultural sustainability, lipids and cell wall polysaccharides may be affected. Contrasting with a plethora of studies reporting the impact of environment and fertilizer on cereal proteins, there is a real lack of information on this particular topic for these minor compounds. However, our knowledge of the physico-chemical properties and biosynthesis of these minor compounds allows us to assess the likely strong impact of environmental and agronomic constraints on the relationships between cell wall polysaccharides, lipids and cereal quality.