The heterogeneous distribution of α-amylase and endoxylanase activity over a population of preharvest sprouted wheat kernels and their localization in individual kernels

To develop targeted approaches to improve the quality of preharvest sprouted (PHS) wheat as a raw material for food manufacturing, knowledge on the nature and distribution of hydrolytic enzymes in PHS wheat is crucial. Results of the present study indicate that α-amylase and endoxylanase activities are heterogeneously distributed among a population of PHS kernel. Within individual severely sprouted kernels, the enzyme activities are heterogeneously distributed throughout the different tissues. α-Amylase activity, almost exclusively of endogenous nature, is mainly detected in the germ region and to a lesser extent in the aleurone layer. Endoxylanase activity is predominantly of microbial origin and located on the kernel surface. In spite of this, light and epifluorescence microscopy show decreased kernel integrity and cell wall breakdown in the crushed cells layer, the endosperm, and the aleurone layer in a selection of kernels upon preharvest sprouting. This knowledge offers opportunities for the development of treatments to reduce the enzyme load in PHS wheat at postharvest level to improve its flour quality.     

优质杂粮‘苏裸麦2号’的选育及其产业化应用

本研究介绍了优质杂粮?苏裸麦2号?的选育背景、过程和栽培技术,该品种有效穗适中,穗型较大,每穗实粒数较多,千粒重中等,丰产性较好,抗逆性中等,品质较好,可作优质杂粮开发利用;研发了以?裸大麦2号?等裸大麦品种青籽粒为原料制作的?冷蒸?食物、裸大麦干籽为原料制作的裸大麦面条、速食裸大麦粉和裸大麦面疙瘩等系列产品;构建了?科企融合、农旅对接?的产业技术推广与开发模式;阐述了裸大麦产业化的发展前景。     

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.     

Nitrogen efficiency components of winter cereals

A model to describe the importance of different physiological processes to explain grain yield differences (ΔG_w) between cropping systems (Huggins and Pan, 1993) was modified to evaluate the nitrogen use efficiency of different cereals. The method uses measurements of grain yield (G_w), grain N (N_g), above-ground plant biomass (B), above-ground plant N (N_t), applied fertilizer N (N_f), and post-harvest inorganic soil N in control plots without fertilizer (N_h). The components are N supply (N_s), N uptake efficiency (N_t/N_s), assimilation efficiency (B/N_t), harvest index (G_w/B) and N harvest index (N_g/N_t). For a first verification of the model different winter cereal species, i.e., one genotype of winter wheat, one of winter rye and one of spelt wheat, were compared in a 2-year field experiments at two sites with different soil fertility and climate. The modified nitrogen efficiency component analysis provided a good understanding of yield differences at different levels of applied N and soil fertility. The method could be useful for selection of genotypes with a high N use efficiency in breeding programmes.     

The impact of sowing density of small grains on rill and ephemeral gully erosion in concentrated flow zones

Despite the fact that soil erosion by water causes considerable on-site and off-site problems, farmers in Europe are reluctant to adopt prevention and control measures when such measures require additional labour and material inputs. This paper documents the impact of multiple sowing of small grains on concentrated flow erosion rates and grain production for a winter triticale field (X Triticosecale Wittmack ex. A. Camus) in the Belgian loess belt. Multiple sowing refers to drilling more than once in zones of concentrated flow erosion in order to increase the total root mass in this zone. Multiple sowing strongly altered the morphology of erosion channels and reduced soil loss significantly. Statistical analysis confirmed that differences in channel dimensions could be explained by the seedling density. Doubling the root mass in the topsoil by multiple sowing, resulted on average in a reduction of soil loss by 42% for the whole growing season. For the winter period, soil loss reduction, mainly attributed to the triticale roots, amounted even to 53%, showing the tremendous impact of seedling roots on soil erosion by concentrated overland flow in the early stages of vegetation growth. Furthermore, total grain yield in the multiple drilled zones was not significantly smaller compared to the conventionally drilled parts of the field. Grain size of cereals was slightly smaller. The results of this case study indicate that double sowing in concentrated overland flow zones may be a viable soil erosion control technique.     

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.     

Improving the protein content and composition of cereal grain

Cereals are important sources of protein for human nutrition but have low quality due to limitations in the amounts of essential amino acids, notably lysine. These deficiencies result from the low levels of these amino acids in the prolamin storage proteins and hence are exacerbated when high levels of nitrogen fertiliser are used to increase yield and total protein content.Genetic and genetic engineering strategies to increase both total protein content and the composition of essential amino acids have been employed. These include the exploitation of mutant high lysine genes and the use of transformation to either express additional proteins which are rich in lysine and/or methionine or to increase the free pools of these amino acids.     

Global status of nematode problems of groundnut, pigeonpea, chickpea, sorghum and pearl millet, and suggestions for future work

Analysis of responses received from 40 cooperators in 20 countries to a questionnaire on nematode problems of groundnut, pigeonpea, chickpea, sorghum and pearl millet suggested that Meloidogyne spp. are internationally important nematode pests of groundnut, chickpea and pigeonpea. Pratylenchus spp. are important on all the five crops. In India, Heterodera cajani and Rotylenchulus reniformis are important pathogens of pigeonpea. Over the last 10–15 years, extensive nematode disease surveys have been undertaken for these crops in Australia, Egypt, India, Jamaica, Senegal, Sudan, Thailand and Zimbabwe; however, < 10% of the total crop areas were covered by these surveys. Except for Brazil, Egypt, USA and Zimbabwe, growers do not use nematicides to control the nematodes. Cultural practices, especially crop rotations, are the most commonly used control measures. Species of Meloidogyne, Pratylenchus and Rotylenchulus on the legumes, and species of Hoplolaimus, Pratylenchus, Quinisulcius and Xiphinema on the cereals, are strongly suspected of increasing the severity of fungal diseases. Work aimed at finding host resistance is being done in Brazil, Fiji, India and the USA, and some sources of resistance have been identified against Meloidogyne arenaria, M. incognita, M. javanica and R. reniformis. Facilities for resistance screening work now exist in many countries. Information on damage thresholds of important pest species are available only from Brazil, Fiji, India and the USA.     

XIP-type endoxylanase inhibitors in different cereals

Highly pure XIP-type (for Xylanase Inhibiting Protein) endoxylanase inhibitor fractions were selectively obtained with a high yield from rye, durum wheat, barley, and maize extracts by affinity chromatography with immobilised Aspergillus niger endoxylanase Xyn1 following removal of the TAXI-type (for Triticum aestivum xylanase inhibitor) endoxylanase inhibitors by affinity chromatography with immobilised Bacillus subtilis endoxylanase XynA. No inhibitors belonging to the XIP family occur in rice, oats, and buckwheat. N-terminal amino acid sequences of the non-wheat XIP-type inhibitors were very similar or identical to those of wheat XIP-1, a chitinase homologue. The isolated inhibitors are basic, monomeric proteins of ca. 30 kDa with pI values of at least 8.5 (rye, durum wheat, and barley XIP) and ca. 7.0 (maize XIP). They are, in general, active against fungal endoxylanases and do not hydrolyse chitin. SDS–PAGE analysis and high-resolution cation exchange chromatography suggest the presence of multiple XIP-type isoinhibitors in the different cereals.     

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.