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1.
Improvement and Re-Evolution of Tetraploid Wheat for Global Environmental Challenge and Diversity Consumption Demand.
Yang, F, Zhang, J, Liu, Q, Liu, H, Zhou, Y, Yang, W, Ma, W
International journal of molecular sciences. 2022;(4)
Abstract
Allotetraploid durum wheat is the second most widely cultivated wheat, following hexaploid bread wheat, and is one of the major protein and calorie sources of the human diet. However, durum wheat is encountered with a severe grain yield bottleneck due to the erosion of genetic diversity stemming from long-term domestication and especially modern breeding programs. The improvement of yield and grain quality of durum wheat is crucial when confronted with the increasing global population, changing climate environments, and the non-ignorable increasing incidence of wheat-related disorders. This review summarized the domestication and evolution process and discussed the durum wheat re-evolution attempts performed by global researchers using diploid einkorn, tetraploid emmer wheat, hexaploid wheat (particularly the D-subgenome), etc. In addition, the re-evolution of durum wheat would be promoted by the genetic enrichment process, which could diversify allelic combinations through enhancing chromosome recombination (pentaploid hybridization or pairing of homologous chromosomes gene Ph mutant line induced homoeologous recombination) and environmental adaptability via alien introgressive genes (wide cross or distant hybridization followed by embryo rescue), and modifying target genes or traits by molecular approaches, such as CRISPR/Cas9 or RNA interference (RNAi). A brief discussion of the future perspectives for exploring germplasm for the modern improvement and re-evolution of durum wheat is included.
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2.
The Adaptation and Tolerance of Major Cereals and Legumes to Important Abiotic Stresses.
Rane, J, Singh, AK, Kumar, M, Boraiah, KM, Meena, KK, Pradhan, A, Prasad, PVV
International journal of molecular sciences. 2021;(23)
Abstract
Abiotic stresses, including drought, extreme temperatures, salinity, and waterlogging, are the major constraints in crop production. These abiotic stresses are likely to be amplified by climate change with varying temporal and spatial dimensions across the globe. The knowledge about the effects of abiotic stressors on major cereal and legume crops is essential for effective management in unfavorable agro-ecologies. These crops are critical components of cropping systems and the daily diets of millions across the globe. Major cereals like rice, wheat, and maize are highly vulnerable to abiotic stresses, while many grain legumes are grown in abiotic stress-prone areas. Despite extensive investigations, abiotic stress tolerance in crop plants is not fully understood. Current insights into the abiotic stress responses of plants have shown the potential to improve crop tolerance to abiotic stresses. Studies aimed at stress tolerance mechanisms have resulted in the elucidation of traits associated with tolerance in plants, in addition to the molecular control of stress-responsive genes. Some of these studies have paved the way for new opportunities to address the molecular basis of stress responses in plants and identify novel traits and associated genes for the genetic improvement of crop plants. The present review examines the responses of crops under abiotic stresses in terms of changes in morphology, physiology, and biochemistry, focusing on major cereals and legume crops. It also explores emerging opportunities to accelerate our efforts to identify desired traits and genes associated with stress tolerance.
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3.
Genomics Associated Interventions for Heat Stress Tolerance in Cool Season Adapted Grain Legumes.
Kumar, J, Mir, RR, Shafi, S, Sen Gupta, D, Djalovic, I, Miladinovic, J, Kumar, R, Kumar, S, Kumar, R
International journal of molecular sciences. 2021;(1)
Abstract
Cool season grain legumes occupy an important place among the agricultural crops and essentially provide multiple benefits including food supply, nutrition security, soil fertility improvement and revenue for farmers all over the world. However, owing to climate change, the average temperature is steadily rising, which negatively affects crop performance and limits their yield. Terminal heat stress that mainly occurred during grain development phases severely harms grain quality and weight in legumes adapted to the cool season, such as lentils, faba beans, chickpeas, field peas, etc. Although, traditional breeding approaches with advanced screening procedures have been employed to identify heat tolerant legume cultivars. Unfortunately, traditional breeding pipelines alone are no longer enough to meet global demands. Genomics-assisted interventions including new-generation sequencing technologies and genotyping platforms have facilitated the development of high-resolution molecular maps, QTL/gene discovery and marker-assisted introgression, thereby improving the efficiency in legumes breeding to develop stress-resilient varieties. Based on the current scenario, we attempted to review the intervention of genomics to decipher different components of tolerance to heat stress and future possibilities of using newly developed genomics-based interventions in cool season adapted grain legumes.
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4.
Evolutionary innovations driving abiotic stress tolerance in C4 grasses and cereals.
Pardo, J, VanBuren, R
The Plant cell. 2021;(11):3391-3401
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Abstract
Grasslands dominate the terrestrial landscape, and grasses have evolved complex and elegant strategies to overcome abiotic stresses. The C4 grasses are particularly stress tolerant and thrive in tropical and dry temperate ecosystems. Growing evidence suggests that the presence of C4 photosynthesis alone is insufficient to account for drought resilience in grasses, pointing to other adaptations as contributing to tolerance traits. The majority of grasses from the Chloridoideae subfamily are tolerant to drought, salt, and desiccation, making this subfamily a hub of resilience. Here, we discuss the evolutionary innovations that make C4 grasses so resilient, with a particular emphasis on grasses from the Chloridoideae (chloridoid) and Panicoideae (panicoid) subfamilies. We propose that a baseline level of resilience in chloridoid ancestors allowed them to colonize harsh habitats, and these environments drove selective pressure that enabled the repeated evolution of abiotic stress tolerance traits. Furthermore, we suggest that a lack of evolutionary access to stressful environments is partially responsible for the relatively poor stress resilience of major C4 crops compared to their wild relatives. We propose that chloridoid crops and the subfamily more broadly represent an untapped reservoir for improving resilience to drought and other abiotic stresses in cereals.
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5.
Bioactive Components in Oat and Barley Grain as a Promising Breeding Trend for Functional Food Production.
Shvachko, NA, Loskutov, IG, Semilet, TV, Popov, VS, Kovaleva, ON, Konarev, AV
Molecules (Basel, Switzerland). 2021;(8)
Abstract
Cereal crops, such as oats and barley, possess a number of valuable properties that meet the requirements for functional diet components. This review summarized the available information about bioactive compounds of oat and barley grain. The results of studying the structure and physicochemical properties of the cell wall polysaccharides of barley and oat are presented. The main components of the flavonoids formation pathway are shown and data, concerning anthocyanins biosynthesis in various barley tissues, are discussed. Moreover, we analyzed the available information about structural and regulatory genes of anthocyanin biosynthesis in Hordeum vulgare L. genome, including β-glucan biosynthesis genes in Avena sativa L species. However, there is not enough knowledge about the genes responsible for biosynthesis of β-glucans and corresponding enzymes and plant polyphenols. The review also covers contemporary studies about collections of oat and barley genetic resources held by the N.I. Vavilov All-Russian Institute of Plant Genetic Resources (VIR). This review intended to provide information on the processes of biosynthesis of biologically active compounds in cereals that will promote further researches devoted to transcription factors controlling expression of structural genes and their role in other physiological processes in higher plants. Found achievements will allow breeders to create new highly productive varieties with the desirable properties.
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6.
Genome editing in cereal crops: an overview.
Matres, JM, Hilscher, J, Datta, A, Armario-Nájera, V, Baysal, C, He, W, Huang, X, Zhu, C, Valizadeh-Kamran, R, Trijatmiko, KR, et al
Transgenic research. 2021;(4):461-498
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Abstract
Genome-editing technologies offer unprecedented opportunities for crop improvement with superior precision and speed. This review presents an analysis of the current state of genome editing in the major cereal crops- rice, maize, wheat and barley. Genome editing has been used to achieve important agronomic and quality traits in cereals. These include adaptive traits to mitigate the effects of climate change, tolerance to biotic stresses, higher yields, more optimal plant architecture, improved grain quality and nutritional content, and safer products. Not all traits can be achieved through genome editing, and several technical and regulatory challenges need to be overcome for the technology to realize its full potential. Genome editing, however, has already revolutionized cereal crop improvement and is poised to shape future agricultural practices in conjunction with other breeding innovations.
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7.
Brassinosteroids and the Tolerance of Cereals to Low and High Temperature Stress: Photosynthesis and the Physicochemical Properties of Cell Membranes.
Sadura, I, Janeczko, A
International journal of molecular sciences. 2021;(1)
Abstract
Cereals, which belong to the Poaceae family, are the most economically important group of plants. Among abiotic stresses, temperature stresses are a serious and at the same time unpredictable problem for plant production. Both frost (in the case of winter cereals) and high temperatures in summer (especially combined with a water deficit in the soil) can result in significant yield losses. Plants have developed various adaptive mechanisms that have enabled them to survive periods of extreme temperatures. The processes of acclimation to low and high temperatures are controlled, among others, by phytohormones. The current review is devoted to the role of brassinosteroids (BR) in cereal acclimation to temperature stress with special attention being paid to the impact of BR on photosynthesis and the membrane properties. In cereals, the exogenous application of BR increases frost tolerance (winter rye, winter wheat), tolerance to cold (maize) and tolerance to a high temperature (rice). Disturbances in BR biosynthesis and signaling are accompanied by a decrease in frost tolerance but unexpectedly an improvement of tolerance to high temperature (barley). BR exogenous treatment increases the efficiency of the photosynthetic light reactions under various temperature conditions (winter rye, barley, rice), but interestingly, BR mutants with disturbances in BR biosynthesis are also characterized by an increased efficiency of PSII (barley). BR regulate the sugar metabolism including an increase in the sugar content, which is of key importance for acclimation, especially to low temperatures (winter rye, barley, maize). BR either participate in the temperature-dependent regulation of fatty acid biosynthesis or control the processes that are responsible for the transport or incorporation of the fatty acids into the membranes, which influences membrane fluidity (and subsequently the tolerance to high/low temperatures) (barley). BR may be one of the players, along with gibberellins or ABA, in acquiring tolerance to temperature stress in cereals (particularly important for the acclimation of cereals to low temperature).
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Roles of Brassinosteroids in Mitigating Heat Stress Damage in Cereal Crops.
Kothari, A, Lachowiec, J
International journal of molecular sciences. 2021;(5)
Abstract
Heat stress causes huge losses in the yield of cereal crops. Temperature influences the rate of plant metabolic and developmental processes that ultimately determine the production of grains, with high temperatures causing a reduction in grain yield and quality. To ensure continued food security, the tolerance of high temperature is rapidly becoming necessary. Brassinosteroids (BR) are a class of plant hormones that impact tolerance to various biotic and abiotic stresses and regulate cereal growth and fertility. Fine-tuning the action of BR has the potential to increase cereals' tolerance and acclimation to heat stress and maintain yields. Mechanistically, exogenous applications of BR protect yields through amplifying responses to heat stress and rescuing the expression of growth promoters. Varied BR compounds and differential signaling mechanisms across cereals point to a diversity of mechanisms that can be leveraged to mitigate heat stress. Further, hormone transport and BR interaction with other molecules in plants may be critical to utilizing BR as protective agrochemicals against heat stress. Understanding the interplay between heat stress responses, growth processes and hormone signaling may lead us to a comprehensive dogma of how to tune BR application for optimizing cereal growth under challenging environments in the field.
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9.
Molecular and Genetic Aspects of Grain Number Determination in Rice (Oryza sativa L.).
Yin, C, Zhu, Y, Li, X, Lin, Y
International journal of molecular sciences. 2021;(2)
Abstract
Rice grain yield is a complex trait determined by three components: panicle number, grain number per panicle (GNPP) and grain weight. GNPP is the major contributor to grain yield and is crucial for its improvement. GNPP is determined by a series of physiological and biochemical steps, including inflorescence development, formation of rachis branches such as primary rachis branches and secondary rachis branches, and spikelet specialisation (lateral and terminal spikelets). The molecular genetic basis of GNPP determination is complex, and it is regulated by numerous interlinked genes. In this review, panicle development and the determination of GNPP is described briefly, and GNPP-related genes that influence its determination are categorised according to their regulatory mechanisms. We introduce genes related to rachis branch development and their regulation of GNPP, genes related to phase transition (from rachis branch meristem to spikelet meristem) and their regulation of GNPP, and genes related to spikelet specialisation and their regulation of GNPP. In addition, we describe other GNPP-related genes and their regulation of GNPP. Research on GNPP determination suggests that it is possible to cultivate rice varieties with higher grain yield by modifying GNPP-related genes.
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10.
Starch biosynthesis in cereal endosperms: An updated review over the last decade.
Huang, L, Tan, H, Zhang, C, Li, Q, Liu, Q
Plant communications. 2021;(5):100237
Abstract
Starch is a vital energy source for living organisms and is a key raw material and additive in the food and non-food industries. Starch has received continuous attention in multiple research fields. The endosperm of cereals (e.g., rice, corn, wheat, and barley) is the most important site for the synthesis of storage starch. Around 2010, several excellent reviews summarized key progress in various fields of starch research, serving as important references for subsequent research. In the past 10 years, many achievements have been made in the study of starch synthesis and regulation in cereals. The present review provides an update on research progress in starch synthesis of cereal endosperms over the past decade, focusing on new enzymes and non-enzymatic proteins involved in starch synthesis, regulatory networks of starch synthesis, and the use of elite alleles of starch synthesis-related genes in cereal breeding programs. We also provide perspectives on future research directions that will further our understanding of cereal starch biosynthesis and regulation to support the rational design of ideal quality grain.