Molecular Insights into Inflorescence Meristem Specification for Yield Potential in Cereal Crops

Flowering plants develop new organs throughout their life cycle. The vegetative shoot apical meristem (SAM) generates leaf whorls, branches and stems, whereas the reproductive SAM, called the inflorescence meristem (IM), forms florets arranged on a stem or an axis. In cereal crops, the inflorescence producing grains from fertilized florets makes the major yield contribution, which is determined by the numbers and structures of branches, spikelets and florets within the inflorescence. The developmental progression largely depends on the activity of IM. The proper regulations of IM size, specification and termination are outcomes of complex interactions between promoting and restricting factors/signals. Here, we focus on recent advances in molecular mechanisms underlying potential pathways of IM identification, maintenance and differentiation in cereal crops, including rice (Oryza sativa), maize (Zea mays), wheat (Triticum aestivum), and barley (Hordeum vulgare), highlighting the researches that have facilitated grain yield by, for example, modifying the number of inflorescence branches. Combinatorial functions of key regulators and crosstalk in IM determinacy and specification are summarized. This review delivers the knowledge to crop breeding applications aiming to the improvements in yield performance and productivity.     

Application of CRISPR/Cas9 in Crop Quality Improvement

The various crop species are major agricultural products and play an indispensable role in sustaining human life. Over a long period, breeders strove to increase crop yield and improve quality through traditional breeding strategies. Today, many breeders have achieved remarkable results using modern molecular technologies. Recently, a new gene-editing system, named the clustered regularly interspaced short palindromic repeats (CRISPR)/Cas9 technology, has also succeeded in improving crop quality. It has become the most popular tool for crop improvement due to its versatility. It has accelerated crop breeding progress by virtue of its precision in specific gene editing. This review summarizes the current application of CRISPR/Cas9 technology in crop quality improvement. It includes the modulation in appearance, palatability, nutritional components and other preferred traits of various crops. In addition, the challenge in its future application is also discussed.     

The effect of foliar supplements of potassium nitrate and urea on the yield of winter wheat

Winter wheat crops were grown with ostensibly adequate supplies of all soil nutrients in 1990 and 1991 with the aim of testing if late foliar supplements of K and N, applied at key development stages, could improve grain yield and grain N content. Foliar sprays of KNO₃ solution, supplying up to 40 kg K ha^–1 in total, at flag leaf unfolded, inflorescence completed and the watery-ripe stage of grain filling, had no effect on yield, yield components or grain N. Urea, supplying 40 kg N ha^–1 at flag leaf unfolded, had no effects on grain yield and grain N in 1990, but in 1991 grain N was increased by 0.14% whilst yield was reduced by up to 0.6 t ha^–1. Urea scorched flag leaf tips in both years. In 1990, the spring was very dry and foliar supplements might have been expected to have had an effect, but on this highly fertile soil all crop K and N requirements were met from the soil.     

Recent Progress in Enhancing Fungal Disease Resistance in Ornamental Plants

Fungal diseases pose a major threat to ornamental plants, with an increasing percentage of pathogen-driven host losses. In ornamental plants, management of the majority of fungal diseases primarily depends upon chemical control methods that are often non-specific. Host basal resistance, which is deficient in many ornamental plants, plays a key role in combating diseases. Despite their economic importance, conventional and molecular breeding approaches in ornamental plants to facilitate disease resistance are lagging, and this is predominantly due to their complex genomes, limited availability of gene pools, and degree of heterozygosity. Although genetic engineering in ornamental plants offers feasible methods to overcome the intrinsic barriers of classical breeding, achievements have mainly been reported only in regard to the modification of floral attributes in ornamentals. The unavailability of transformation protocols and candidate gene resources for several ornamental crops presents an obstacle for tackling the functional studies on disease resistance. Recently, multiomics technologies, in combination with genome editing tools, have provided shortcuts to examine the molecular and genetic regulatory mechanisms underlying fungal disease resistance, ultimately leading to the subsequent advances in the development of novel cultivars with desired fungal disease-resistant traits, in ornamental crops. Although fungal diseases constitute the majority of ornamental plant diseases, a comprehensive overview of this highly important fungal disease resistance seems to be insufficient in the field of ornamental horticulture. Hence, in this review, we highlight the representative mechanisms of the fungal infection-related resistance to pathogens in plants, with a focus on ornamental crops. Recent progress in molecular breeding, genetic engineering strategies, and RNAi technologies, such as HIGS and SIGS for the enhancement of fungal disease resistance in various important ornamental crops, is also described.     

Evaluation of triticale bran as raw material for bioethanol production

The present work addresses the introduction of second generation biofuels from agricultural by-products generated from low input cereal crops such as triticale. The main purpose was to investigate whether the overall ethanol yield in a triticale dry-mill ethanol plant could be increased by combination of pretreatment and enzymatic hydrolysis of the bran obtained by fractionation of the grain to separate from starch. Different dilute acid pretreatment conditions were studied using starch-free triticale bran (SFTB) as substrate at a fixed loading of 10% (dry weight/volume). A statistically experimental design approach, based on previous studies, was used to evaluate the sugar recovery so as to maximize the enzyme digestibility of the pretreated material. The highest overall sugar yield was attained by using 0.1% (w/v) of sulphuric acid at 160 °C for 22.5 min. At these conditions, it could be possible to obtain up to 245 L of ethanol per dry ton of SFTB considering hexose and pentose sugars fermentation, which would increase by 14% the theoretical ethanol yield in a dry-mill ethanol plant.     

The Potential of Genome Editing for Improving Seed Oil Content and Fatty Acid Composition in Oilseed Crops

A continuous rise in demand for vegetable oils, which comprise mainly the storage lipid triacylglycerol, is fueling a surge in research efforts to increase seed oil content and improve fatty acid composition in oilseed crops. Progress in this area has been achieved using both conventional breeding and transgenic approaches to date. However, further advancements using traditional breeding methods will be complicated by the polyploid nature of many oilseed crops and associated time constraints, while public perception and the prohibitive cost of regulatory processes hinders the commercialization of transgenic oilseed crops. As such, genome editing using CRISPR/Cas is emerging as a breakthrough breeding tool that could provide a platform to keep pace with escalating demand while potentially minimizing regulatory burden. In this review, we discuss the technology itself and progress that has been made thus far with respect to its use in oilseed crops to improve seed oil content and quality. Furthermore, we examine a number of genes that may provide ideal targets for genome editing in this context, as well as new CRISPR-related tools that have the potential to be applied to oilseed plants and may allow additional gains to be made in the future.     

Dual Reproductive Cell-Specific Promoter-Mediated Split-Cre/LoxP System Suitable for Exogenous Gene Deletion in Hybrid Progeny of Transgenic Arabidopsis

Genetically modified (GM) crops possess some superior characteristics, such as high yield and insect resistance, but their biosafety has aroused broad public concern. Some genetic engineering technologies have recently been proposed to remove exogenous genes from GM crops. Few approaches have been applied to maintain advantageous traits, but excising exogenous genes in seeds or fruits from these hybrid crops has led to the generation of harvested food without exogenous genes. In a previous study, split-Cre mediated by split intein could recombine its structure and restore recombination activity in hybrid plants. In the current study, the recombination efficiency of split-Cre under the control of ovule-specific or pollen-specific promoters was validated by hybridization of transgenic Arabidopsis containing the improved expression vectors. In these vectors, all exogenous genes were flanked by two loxP sites, including promoters, resistance genes, reporter genes, and split-Cre genes linked to the reporter genes via LP4/2A. A gene deletion system was designed in which NCre was driven by proDD45, and CCre was driven by proACA9 and proDLL. Transgenic lines containing NCre were used as paternal lines to hybridize with transgenic lines containing CCre. Because this hybridization method results in no co-expression of the NCre and CCre genes controlled by reproduction-specific promoters in the F1 progeny, the desirable characteristics could be retained. After self-crossing in F1 progeny, the expression level and protein activity of reporter genes were detected, and confirmed that recombination of split-Cre had occurred and the exogenous genes were partially deleted. The gene deletion efficiency represented by the quantitative measurements of GUS enzyme activity was over 59%, with the highest efficiency of 73% among variable hybrid combinations. Thus, in the present study a novel dual reproductive cell-specific promoter-mediated gene deletion system was developed that has the potential to take advantage of the merits of GM crops while alleviating biosafety concerns.     

Genotypische Variabilität in Ertrags- und Qualitätsmerkmalen bei Mohn und Leindotter

Genotypic Variation for Yield-and Quality-Traits in Poppy and False Flax Within the two old, in earlier times cultivated crops there exists a large variability in such important traits as 1000-seed-weight, oil content, oil yield, and fatty acid composition. Making use of the variability by intensive breeding efforts would lead to high yielding poppy strains with a content of linoleic acid up to 80% and to high yielding false flax lines with a fatty acid composition comparable to that of linseed oil.     

Proofing Direct-Seeded Rice with Better Root Plasticity and Architecture

The underground reserve (root) has been an uncharted research territory with its untapped genetic variation yet to be exploited. Identifying ideal traits and breeding new rice varieties with efficient root system architecture (RSA) has great potential to increase resource-use efficiency and grain yield, especially under direct-seeded rice, by adapting to aerobic soil conditions. In this review, we tried to mine the available research information on the direct-seeded rice (DSR) root system to highlight the requirements of different root traits such as root architecture, length, number, density, thickness, diameter, and angle that play a pivotal role in determining the uptake of nutrients and moisture at different stages of plant growth. RSA also faces several stresses, due to excess or deficiency of moisture and nutrients, low or high temperature, or saline conditions. To counteract these hindrances, adaptation in response to stress becomes essential. Candidate genes such as early root growth enhancer PSTOL1, surface rooting QTL qSOR1, deep rooting gene DRO1, and numerous transporters for their respective nutrients and stress-responsive factors have been identified and validated under different circumstances. Identifying the desired QTLs and transporters underlying these traits and then designing an ideal root architecture can help in developing a suitable DSR cultivar and aid in further advancement in this direction.     

A simple model for estimating the nitrogen fertilizer requirement of a cereal crop

A static model that predicts the nitrogen (N) fertilizer requirement of grain sorghum or wheat crops is described. Inputs required by the model are soil nitrate-N (kg ha^–1) in the profile at sowing, total N (%) in the plough layer, available water in the profile at sowing (mm) plus rainfall during the growing season (mm). Output includes fertilizer N required for both maximum yield and optimum economic yield.The model was tested by using published field data from Nebraska and Kansas (U.S.A.), South Australia and Northern Territory (Australia), and Saskatchewan (Canada). The model was accurate when no fertilizer N was required, and when large amounts were required, but quantitative prediction of moderate requirements was only fair. Predictions for grain sorghum were better than for winter wheat, probably because total water use was a better predictor of yield potential for grain sorghum than for winter wheat. Further refinement for specific environments should make the model practical for dryland cereal crops.     

Physical,culinary and nutritional characterization in dry bean from the highlands of Mexico

In the improvement of a given crop species, knowledge on the grain quality and related traits in the progenitors used in the breeding process is needed to establish their usefulness as a source of a given character, and as well as to plan the proper combinations between progenitors. The aim of the present research was to characterize a group of 49 genotypes of Phaseolus vulgaris and one of Phaseolus coccineus, in relation to physical, cooking and nutritional grain traits. Cultivar Blanco Tlaxcala (P. coccineus) showed a larger grain size and lower protein content than any of the P. vulgaris cultivars. The 86% of the studied genotypes showed cooking times lower to 115 min, and a significant correlation between this trait and water sorption capacity (r = 0.78 **) was found. Cultivars Redlands Pioneer and ICA Zerinza could be used as source of low cooking time; and Perry Marrow, Kaboon and ICA Zerinza in the production of low shell content cultivars. Genotypes G 2333, Negro Lolotla, REN 27 and J 117 showed the highest grain protein content. On the other hand, BY 94022, Pinto Villa and Negro 150 had the lowest trypsin inhibitor activity. Results support the possible use of the above genotypes as sources of those grain traits. In general, large variability was found for most of the quality traits determined; therefore, there is scope for improvement through recombination and selection.     

Nitrogen fixation of red clover interseeded with winter cereals across a management-induced fertility gradient

The incorporation of legume cover crops into annual grain rotations remains limited, despite extensive evidence that they can reduce negative environmental impacts of agroecosystems while maintaining crop yields. Diversified grain rotations that include a winter cereal have a unique niche for interseeding cover crops. To understand how management-driven soil fertility differences and inter-seeding with grains influenced red clover (Trifolium pratense) N₂ fixation, we estimated biological N₂ fixation (BNF) in 2006 and 2007, using the ¹⁵N natural abundance method across 15 farm fields characterized based on the reliance on BNF derived N inputs as a fraction of total N inputs. Plant treatments included winter grain with and without interseeded red clover, monoculture clover, monoculture orchardgrass (Dactylis glomerata), and clover-orchardgrass mixtures. Fields with a history of legume-based management had larger labile soil nitrogen pools and lower soil P levels. Orchardgrass biomass was positively correlated with the management-induced N fertility gradient, but we did not detect any relationship between soil N availability and clover N₂ fixation. Interseeding clover with a winter cereal did not alter winter grain yield, however, clover production was lower during the establishment year when interseeded with taller winter grain varieties, most likely due to competition for light. Interseeding clover increased the % N from fixation relative to the monoculture clover (72% vs. 63%, respectively) and the average total N₂ fixed at the end of the first growing season (57 vs. 47 kg N ha⁻¹, respectively). Similar principles could be applied to develop more cash crop-cover crop complementary pairings that provide both an annual grain harvest and legume cover crop benefits.     

Effects of Drought Stress on Oil Characteristics of <Emphasis Type="Italic">Carthamus</Emphasis> Species

Safflower (Carthamus tinctorius L.) is one of the oldest domesticated crops, mainly grown as oilseed in the arid and semi arid regions of the world. Cross‐ability of Carthamus species has made wild safflower species a suitable source for transferring drought tolerant genes to cultivated species. This study was conducted to investigate seed yield per plant, oil content and fatty acid composition of some Carthamus species and to identify the effects of drought stress on these measured traits. In this regard, 27 genotypes from C. tinctorius, C. palaestinus, C. oxyacanthus, C. lanatus and C. glaucus were planted in the field under normal and drought‐stress conditions for two years. Results showed that some studied species differed in oil content, seed yield per plant and fatty acid profiles. As an example, the highest seed oil content (32%) was found in genotype number 22 from C. palaestinus, and the lowest (18%) was obtained for the genotype number 11 from C. lanatus. For all the species, oil content was not affected by moisture stress and did not change over different environments. Similar and stable responses of various Carthamus species for fatty acid composition indicated that hybridization between these species for genetic improvement of drought tolerance may have no adverse effects on oil quality. Considerable diversity within species for all measured traits, similarity in fatty acid profiles and almost the same pattern of changes under drought stress showed that the wild species especially the crossable ones, are good candidates to be used in breeding of cultivated safflower.     

Spent mushroom compost as a nitrogen source for spring barley

Spent mushroom compost (SMC) contains a range of plant nutrients, including nitrogen (N), a large proportion of which originate from arable crops. Using SMC as an organic fertilizer for crops recycles these nutrients. Effective use of SMC in fertilizer regimes requires knowledge of the nitrogen fertilizer value (NFV) of the SMC, which is the amount of mineral fertilizer N required to give the same N yield, or marketable yield, as an application of SMC. The objectives of these experiments were to evaluate the effect of SMC on spring barley grain yield and quality and to determine its NFV. Experiments were carried out on two soils, light- and medium-textured, over 3 years (2008–2010). The experiments compared the yield response and N uptake of spring barley to fertilizer N with and without SMC. SMC application gave similar or higher grain yield and N uptake compared to fertilizer only treatments at corresponding fertilizer N rates. SMC had no significant (P > 0.05) effect on the economic optimum fertilizer N rate but the maximum yield was significantly (P < 0.05) higher where SMC was applied in two of the six experiments. Effects of SMC on grain quality were small. Results indicated that the NFV, expressed as a proportion of the total N applied in SMC, ranged from 0.05 to 0.29 kg kg^?1 N applied in SMC, with a mean of 0.15 kg kg^?1. It is concluded that SMC can contribute to the nitrogen nutrition of small grain cereal crops in high yield potential environments.     

Breeding Cereal Crops for Enhanced Weed Suppression: Optimizing Allelopathy and Competitive Ability

Interest in breeding grain crops with improved weed suppressive ability is growing in response to the evolution and rapid expansion of herbicide resistant populations in major weeds of economic importance, environmental concerns, and the unmet needs of organic producers and smallholder farmers without access to herbicides. This review is focused on plant breeding for weed suppression; specifically, field and laboratory screening protocols, genetic studies, and breeding efforts that have been undertaken to improve allelopathy and competition in rice, wheat, and barley. The combined effects of allelopathy and competition determine the weed suppressive potential of a given cultivar, and research groups worldwide have been working to improve both traits simultaneously to achieve maximum gains in weed suppression. Both allelopathy and competitive ability are complex, quantitatively inherited traits that are heavily influenced by environmental factors. Thus, good experimental design and sound breeding procedures are essential to achieve genetic gains. Weed suppressive rice cultivars are now commercially available in the U.S. and China that have resulted from three decades of research. Furthermore, a strong foundation has been laid during the past 10 years for the breeding of weed suppressive wheat and barley cultivars.     

农药氯化苦新工艺的开发

农药氯化苦用于粮食和土境的熏蒸，对经济作物的增产、稳产和改善品质起到其它农药无可替代作用。又由于其对人强烈的刺激和催泪作用，使人不至于中毒。无残留，安全可靠。在对氯化苦合成的多种方法对比的基础上，开发了以硝基甲烷为起始原料经次氯酸钠氯化，蒸馏提纯，生产出氮化苦含量达99．5％以上，总收率达到92％以上。该工艺路线具有流程短、原料易得、产品质量好、收率高、成本低、“三废”少等优点。