Monitoring the Expression Profiles of Cereal Crops Seedlings by Using Rice cDNA Microarray

Through exploiting the high homology of cereal crop genes, membranous cDNA microarrays containing 3 311 unique rice transcripts (including 1 639 endosperm-derived transcripts and 1 672 mature stem-derived transcripts) were used for monitoring the expression profiles of 1-leaf stage seedlings of 4 cereal crop species: rice, maize, sorghum and barley. After hybridizing with [α-33P| labeled probes, 73.6 % of the arrayed genes generated reliable signals in all of the four cercal crops. Further analysis revealed that among the arrayed genes, a higher percentage of the endosperm-derived transcripts (86.6 %) expressed than that of the mature stem-derived genes (60.9 %), indicating that most of the endosperm expressed genes functioned in young seedlings while considerable amount of mature stem tissue expressed genes did not express. These results also inferred that some genes might function only at certain developmental stages. By comparing the obtained profiles, 84 genes were identified constantly expressed in all me four cereal crops. Many housekeeping genes, such as polyubiquitin, ubiquitin conjugating enzyme and ribosomal proteins were included in this catalogue. The experiment also identified 14 rice seedling specifically expressed genes, including 3 biotic and abiotic stress induced genes and 1 apoptosis suppressor encoding gene Bax inhibitor-1. This investigation provided invaluable information for comparative genomics of gramineae members.

Response and resistance of cereal crops to pathogens

The special topic of the two papers is the systemic acquired resistance （SAR） and pathogenesis-related protein genes （PR）. SAR is an enhanced resistance against further potential parasite beyond the initial infection site, which can be induced by either pathogen infection or exogenous inducer, including synthetic chemicals and natural prod- ucts. As a ＂whole-plant＂ resistance defense, SAR confers broad-spectrum immunity to widely diverse pathogenic microorganisms, such as viruses, bacteria and fungi for a relatively long lasting period. Convincingly, it is a promising way to prevent crop diseases by activating the plants＇ own natural defenses via application of chemical inducers or creating resistant wheat cultivars.

Orchestrating seed storage protein and starch accumulation toward overcoming yield–quality trade-off in cereal crops

Achieving high yield and good quality in crops is essential for human food security and health.However,there is usually disharmony between yield and quality.Seed storage protein(SSP)and starch,the predominant components in cereal grains,determine yield and quality,and their coupled synthesis causes a yield–quality trade-off.Therefore,dissection of the underlying regulatory mechanism facilitates simultaneous improvement of yield and quality.Here,we summarize current findings about the synergistic molecular machinery underpinning SSP and starch synthesis in the leading staple cereal crops,including maize,rice and wheat.We further evaluate the functional conservation and differentiation of key regulators and specify feasible research approaches to identify additional regulators and expand insights.We also present major strategies to leverage resultant information for simultaneous improvement of yield and quality by molecular breeding.Finally,future perspectives on major challenges are proposed.

Water stress resilient cereal crops:Lessons from wild relatives

Cereal crops are significant contributors to global diets.As climate change disrupts weather patterns and wreaks havoc on crops,the need for generating stress-resilient,high-yielding varieties is more urgent than ever.One extremely promising avenue in this regard is to exploit the tremendous genetic diversity expressed by the wild ancestors of current day crop species.These crop wild relatives thrive in a range of environments and accordingly often harbor an array of traits that allow them to do so.The identification and introgression of these traits into our staple cereal crops can lessen yield losses in stressful environments.In the last decades,a surge in extreme drought and flooding events have severely impacted cereal crop production.Climate models predict a persistence of this trend,thus reinforcing the need for research on water stress resilience.Here we review:(i)how water stress(drought and flooding)impacts crop performance;and(ii)how identification of tolerance traits and mechanisms from wild relatives of the main cereal crops,that is,rice,maize,wheat,and barley,can lead to improved survival and sustained yields in these crops under water stress conditions.

Wheat streak mosaic virus： incidence in field crops, potential reservoir within grass species and uptake in winter wheat cultivars

Wheat streak mosaic virus（WSMV）has become a re-emerging pathogen in cereal crops in the Czech Republic.WSMV was first reported in the former Czechoslovakia in the early 1980s,and then no record of the virus was documented until 2009.The incidence of the virus was recorded in recent years in several winter wheat fields and many grass species.Here,we surveyed the incidence of WSMV in cereal crops.The results demonstrated the existence of the virus in winter wheat and volunteer wheat during each year of the monitoring period,which spanned from 2013–2016.Although the range of infected samples was low（6.4%of the total tested samples）,a high incidence of well-distributed virus was recorded.In at least six fields,the virus reached severe and potentially epidemic levels.In accordance with our previous report detailing WSMV infection of native grasses,we tested several grass species commonly grown in the Czech Republic.We found that some grass species acted as experimental hosts and possible reservoirs of the virus;these included Anthoxanthum odoratum（sweet vernal grass）,Arrhenatherum elatius（false oat-grass）,Lolium multiflorum（Italian rye-grass）,Bromus japonicus（Japanese chess）,Echinochloa crus-galli（barnyard grass）,Holcus lanatus（meadow soft grass）and Holcus mollis（creeping soft grass）.Some of these grass species are also important weeds of cereals,which may be the potential source of WSMV infection in cereal crops.Several widely used winter wheat cultivars were tested in the field after artificial inoculation with WSMV to evaluate virus titre by RT-qPCR.Overall,the tested cultivars had a low virus titre,which is associated with mild disease symptoms and may provide a good level of crop resistance to WSMV.

Grain Yield and Nitrogen Use Efficiency Vary with Cereal Crop Type and Nitrogen Fertilizer Rate in Ethiopia: A Meta-Analysis

The crop production in Ethiopia is markedly constrained by soil nutrient depletion and limited fertilizer input. Nitrogen is among the most yield-limiting factors of cereal crops, especially in sub-Saharan Africa (SSA). A meta-analysis of 82 studies was carried out to evaluate the response of major cereal crops, viz. wheat, maize, barley, teff, and sorghum, to nitrogen fertilization in Ethiopia. The results showed that N-application significantly increased yields of all the five crops examined herein. The average yields of the treatment effects over controls for the five crops were 3775.8 kg∙ha−1 and 2593.3 kg∙ha−1, respectively. The overall yield response to nitrogen treatments for all the crops was 64.8% (wheat, 96.5%;maize, 40.65%;barley 84.36%;teff, 50.48%;and sorghum;23%). Overall, nitrogen agronomic efficiency (AEN) and partial factor productivity (PFPN) were 18.2 and 71.81 kg∙kg−1, respectively. A downtrend of nitrogen use efficiency with an increase in N rate was realized. The yield response was higher for the nitrogen treatment effects of >100 kg∙N∙ha−1 (123.9%), clay soils (75.46%), low initial soil organic carbon (SOC) and available phosphorous (AP) (92.4% and 101.6%), respectively, Therefore, we recommend the application of nitrogen fertilizer (>100 kg∙N∙ha−1), especially on infertile soils for improved grain yield and NUE in aforementioned cereal crops in Ethiopia and similar regions in sub-Saharan Africa (SSA).

Physiological and Morphological Responses of Susceptible and Resistant Barleys to Bird Cherry-Oat Aphid Feeding

The bird cherry-oat aphid (Rhopalosiphum padi [Linnaeus, 1758]) is considered a key pest of cereal crops worldwide, causing direct damage through sap feeding and by acting as a vector for viral diseases. Managing aphids is challenging because of their biology and potential resistance to insecticides. Developing resistant barley genotypes is a sustainable strategy for managing BCOA. In this study, we assessed responses of susceptible “Morex” and resistant “BCO R001” barley, Hordeum vulgare L. genotypes to different initial BCOA densities (0, 50, 100 or 200 aphids.plant-1). Physiological and morphological parameters were measured weekly for four weeks after infestation. Chlorophyll content, photosynthetic rate, plant aerial fresh and dry weight were greater for the resistant cultivar at lower aphid abundances and up to three weeks after infestation. Carbon assimilation curves (A/Ci) of infested “BCO R001” were similar to controls 15 days post infestation, differing from Morex. However, BCOA infestation of 50 aphid.plant-1 for two weeks negatively impacted the fitness of both genotypes. Initial resistance by BCO R001 to BCOA infestation can allow growers and natural enemies more time contributing to more effective and sustainable management of BCOA infestations.

摩天大厦型作物工厂——保障城市食物快速增长需求的作物高效生产系统

Vertical farming systems,such as sky farms,are a potential type of agricultural system for stable and effective food production.Here,we highlight the potential of the sky farm,denoted as the“skyscraper crop factory”(SCF),for cereal crop production and discuss some nascent technologies that would be applied in this production system.SCFs are ideal crop-production systems for increasing the effective arable area for crops and ensuring food security in times of crises that cause a shock in global trade.They can also provide food in urban areas to meet producers’and consumers’demands for the increased nutrition,taste,and safe production of cereal crops.Moreover,as their use can reduce greenhouse gas emissions,SCFs could be a sustainable addition to conventional agricultural crop production.

Poaceae Orthologs of Rice OsSGL,DUF1645 Domain-Containing Genes,Positively Regulate Drought Tolerance,Grain Length and Weight in Rice

Grain yield is a polygenic trait that can be influenced by environmental factors and genetic compositions at all plant growth stages.Currently,the molecular mechanisms behind the coordination of the interaction between grain yield-related traits remain unknown.In this study,we characterized the function of four STRESS_tolerance and GRAIN_LENGTH(Os SGL)Poaceae ortholog genes that are transcribed into DUF1645 domain-containing proteins in relation to the grain length,grain weight,and drought stress-tolerance of rice.The transgenic plants with overexpressing or heterologous high levels of Poaceae OsSGL ortholog genes exhibited longer grain size than the wild type plants.Larger cells were seen in panicles of the four transgenic lines with paraffin sectioning and scanning electron microscopy analyses.In addition,four Poaceae OsSGL ortholog genes positively affected the drought tolerance of rice.Four transgenic plants displayed higher resistance to drought stress at the seedling and vegetative stages.RNA-sequencing and qRT-PCR results indicated that over-or heterologous-expression of four Poaceae OsSGL ortholog genes also affected the transcriptome of rice plants.These genes may play a role in auxin and cytokinin biosynthesis and their transduction pathways.Taken together,these results suggested that the four OsSGL orthologs have a conserved function in the regulation of stress-tolerance and cell growth by modulating hormonal biosynthesis and signaling.

Organic Amendments Improve Plant Morpho-Physiology and Antioxidant Metabolism in Mitigating Drought Stress in Bread Wheat(Triticum aestivum L.)

Due to the unpredictable climate change,drought stress is being considered as one of the major threats to crop production.Wheat(Triticum aestivum L.cv.BARI Gom-26)being a dry season crop frequently faces scarcity of water and results in a lower yield.Therefore,this experiment aims to explore the role of different organic amendments(OAs)in mitigating drought stress-induced damage.The pot experiment consisted of different organic amendments viz.compost,vermicompost and poultry manure@0.09 kg m^(−2)soil,biochar@2.5%w/w soil and chitosan@1%w/w soil which was imposed on the plants grown under both well-watered and drought conditions.Results showed that drought stress reduced plant height(15%),SPAD value(16%),relative water content(13%),number of spikelet spike^(−1)(17%),number of grains spike^(−1)(12%),and 100-grain weight(18%).Organic amendments act as a protectant and reduce drought stress-induced damages by enhancing the morpho-physiological and yield attributes.Vermicompost enhanced SPAD value by 18%,number of spikelets spike^(−1)by 20%,number of grains spike^(−1)by 17%,whereas poultry manure increased plant height by 16%under drought condition compared to control plant.Unlike other OAs applied,vermicompost was proved to be capable of reducing the higher lipid peroxidation and proline content raised by drought condition.Drought stress-induced increment of catalase,ascorbate peroxidase and glutathione reductase activities were also efficiently modulated by the organic amendment application.The present study concluded that OAs play significant roles in alleviating drought stressinduced damages by improving the morpho-physiological attributes and among the different types of OAs used vermicompost performed better which in addition ceased the production of reactive oxygen species.

Carbon and water footprints of major crop production in India

Scarcity of water and emission of greenhouse gases(GHGs)are the two key environmental issues affecting crop production in India.Reducing the carbon footprint(CF)and water footprint(WF)of crop production can help to mitigate the environmental hazards that stem from GHG emissions and water scarcity.The CFs and WFs of three major cereal crops,rice,wheat,and maize,were estimated for the year 2014 under the environmental conditions in India,based on national statistics and other data sources.Total CFs(TCFs)of rice,wheat,and maize in India were estimated to be 2.44,1.27,and 0.80 t CO_(2)equivalent ha-1,respectively,and product WFs for rice,wheat,and maize in India were 3.52,1.59,and 2.06 m3 kg^(-1),respectively.Blue WF was found to be the highest in West India for rice and in South India for both wheat and maize,with the highest irrigation water use in these regions.There was a positive correlation between TCF and total WF,and hence mitigation of both was possibly simultaneous in various regions in India.Potential measures for mitigating GHG emissions and optimizing water use for rice,wheat,and maize production in India are recommended in this paper.

Light Regulation of Stomatal Development and Patterning: Shifting the Paradigm from Arabidopsis to Grasses

The stomatal pores of plant leaves control gas exchange with the environment.Stomatal development is prevised regulated by both internal genetic programs and environmental cues.Among various environmental factors,light regulation of stomata formation has been extensively studied in Arabidopsis.In this review,we summarize recent advances in the genetic control of stomata development and its regulation by light.We also present a comparative analysis of the conserved and diverged stomatal regulatory networks between Arabidopsis and cereal grasses.Lastly,we provide our perspectives on manipulation of the stomata density on plant leaves for the purpose of breeding crops that are better adapted to the adverse environment and high-density planting conditions.

Genome editing in grass plants

Cereal crops including maize,rice,wheat,sorghum,barley,millet,oats and rye are the major calorie sources in our daily life and also important bioenergy sources of the world.The rapidly advancing and state-of-the-art genome-editing tools such as zinc finger nucleases,TAL effector nucleases,and clustered regularly interspaced short palindromic repeats(CRISPR)/CRISPR-associated systems(CRISPR-Cas9-,CRISPR-Cas12a-and CRISPR/Cas-derived base editors)have accelerated the functional genomics and have promising potential for precision breeding of grass crops.With the availability of annotated genomes of the major cereal crops,application of these established genome-editing toolkits to grass plants holds promise to increase the nutritional value and productivity.Furthermore,these easy-to-use and robust genome-editing toolkits have advanced the reverse genetics for discovery of novel gene functions in crop plants.In this review,we document some of important progress in development and utilization of genome-editing tool sets in grass plants.We also highlight present and future uses of genome-editing toolkits that can sustain and improve the quality of cereal grain for food consumption.