Will epigenetics be a key player in crop breeding? (original) (raw)
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Heritable Epigenetic Variation and its Potential Applications for Crop Improvement
Plant Breeding and Biotechnology, 2013
Phenotypic variation within organisms is driven primarily by genetic diversity. However, there is a growing appreciation that epigenetic variation, resulting from a multitude of diverse chemical modifications to the DNA and chromatin, can have profound effects on phenotype. Heritable epigenetic marks persist through meiosis and can be stably transmitted to the next generation, resulting in transgenerational epigenetic inheritance. Importantly, when epigenetic changes occur near coding genes, affecting their transcriptional state, heritable epigenetic variation can result in heritable phenotypic variation. Large-scale interrogation of epigenome inheritance in Arabidopsis has revealed that spontaneous variation in DNA methylation occurs at a rate that is orders of magnitude greater than genetic mutation, indicating the key importance of epigenetic variation during evolution. Thus, there is a potential for epigenetics to play a role in crop improvement, including regulation of transgene expression and creation of novel epialleles. Here, we review cases of naturally occurring and genetically induced epialleles, and discuss how the studies from two epigenetic populations are rapidly increasing our understanding of epigenetic diversity.
Epigenetics for Crop Improvement in Times of Global Change
Biology
Epigenetics has emerged as an important research field for crop improvement under the on-going climatic changes. Heritable epigenetic changes can arise independently of DNA sequence alterations and have been associated with altered gene expression and transmitted phenotypic variation. By modulating plant development and physiological responses to environmental conditions, epigenetic diversity—naturally, genetically, chemically, or environmentally induced—can help optimise crop traits in an era challenged by global climate change. Beyond DNA sequence variation, the epigenetic modifications may contribute to breeding by providing useful markers and allowing the use of epigenome diversity to predict plant performance and increase final crop production. Given the difficulties in transferring the knowledge of the epigenetic mechanisms from model plants to crops, various strategies have emerged. Among those strategies are modelling frameworks dedicated to predicting epigenetically control...
Can Epigenetics Guide the Production of Better Adapted Cultivars?
Agronomy
As the global population continues to grow, food demand will be reaching levels which current agricultural practices cannot meet. This projected demand combined with the negative impacts of climate change on crop production calls for more careful breeding efforts to develop better adapted plants more tolerant to climate fluctuations. Fortunately, the development of molecular biology techniques like genome, transcriptome and epigenome sequencing now offer new approaches to help classical breeding meet these challenges. This review focuses on the potential of epigenetic approaches, particularly the creation of epigenetic markers (epi-markers) for guiding the selection process in breeding programs. Many studies have indeed successfully linked stable epigenetic modifications to different plant traits of interest but research on the applicability of using epi-markers in breeding programs is still scarce. This review emphasises the current progress that has been made with regards to the u...
Epigenetics and its role in effecting agronomical traits
Frontiers in Plant Science
Climate-resilient crops with improved adaptation to the changing climate are urgently needed to feed the growing population. Hence, developing high-yielding crop varieties with better agronomic traits is one of the most critical issues in agricultural research. These are vital to enhancing yield as well as resistance to harsh conditions, both of which help farmers over time. The majority of agronomic traits are quantitative and are subject to intricate genetic control, thereby obstructing crop improvement. Plant epibreeding is the utilisation of epigenetic variation for crop development, and has a wide range of applications in the field of crop improvement. Epigenetics refers to changes in gene expression that are heritable and induced by methylation of DNA, post-translational modifications of histones or RNA interference rather than an alteration in the underlying sequence of DNA. The epigenetic modifications influence gene expression by changing the state of chromatin, which under...
Epigenome guided crop improvement: current progress and future opportunities
Emerging topics in life sciences, 2022
Epigenomics encompasses a broad field of study, including the investigation of chromatin states, chromatin modifications and their impact on gene regulation; as well as the phenomena of epigenetic inheritance. The epigenome is a multi-modal layer of information superimposed on DNA sequences, instructing their usage in gene expression. As such, it is an emerging focus of efforts to improve crop performance. Broadly, this might be divided into avenues that leverage chromatin information to better annotate and decode plant genomes, and into complementary strategies that aim to identify and select for heritable epialleles that control crop traits independent of underlying genotype. In this review, we focus on the first approach, which we term 'epigenome guided' improvement. This encompasses the use of chromatin profiles to enhance our understanding of the composition and structure of complex crop genomes. We discuss the current progress and future prospects towards integrating this epigenomic information into crop improvement strategies; in particular for CRISPR/Cas9 gene editing and precision genome engineering. We also highlight some specific opportunities and challenges for grain and horticultural crops. Epigenome guided improvement Epigenomics, through its exploration of the combinatorial code of chromatin modifications, can play a role in crop improvement strategies by enriching our understanding of crop genomes and as the molecular basis of traits. The investigation of heritable epigenetic variation that underpins traits in crops is an accelerating area of research with many exciting challenges on the horizon, including better understanding the epigenetic basis of traits, the stability and heritability of epialleles, and the sources of epigenetic variation in crops. These aspects have been reviewed extensively in recent years [1-6]. In this review, we explore the complementary topic of epigenome guided improvement, including the use of chromatin profiles to identify functional genes and cis-regulatory elements (CREs) in crop genomes and the applications of this information to engineer new variation for key traits in crops. The challenge of genome annotation Crop genomes vary dramatically in size [7], ranging from the relatively small genome of rice at ∼400 Mb [8], the large genome of maize at 2.4 Gb [9], through to the huge 17 Gb genome of hexaploid bread wheat [10]. In moderate to large genomes, genes (as we understand them today) are in the minority; they are interspersed between transposable elements (TEs) and other repetitive DNA elements. While the plant genomics community has become very proficient at economically sequencing and assembling entire genomes [11], it remains challenging to identify functional protein-coding genes [12,13]. Even more difficult is the comprehensive identification of all the gene CREs in a genome, largely because the knowledge of DNA sequence alone is usually insufficient to confidently pinpoint these, often small, regions [14,15]. Indeed, the CREs that are critical for controlling genes and agronomic traits can be located in tens of thousands of base pairs from the genes they regulate
Epigenetics: possible applications in climate-smart crop breeding
Journal of Experimental Botany, 2020
To better adapt transiently or lastingly to stimuli from the surrounding environment, the chromatin states in plant cells vary to allow the cells to fine-tune their transcriptional profiles. Modifications of chromatin states involve a wide range of post-transcriptional histone modifications, histone variants, DNA methylation, and activity of non-coding RNAs, which can epigenetically determine specific transcriptional outputs. Recent advances in the area of ‘-omics’ of major crops have facilitated identification of epigenetic marks and their effect on plant response to environmental stresses. As most epigenetic mechanisms are known from studies in model plants, we summarize in this review recent epigenetic studies that may be important for improvement of crop adaptation and resilience to environmental changes, ultimately leading to the generation of stable climate-smart crops. This has paved the way for exploitation of epigenetic variation in crop breeding.
From epigenetics to epigenomics and their implications in plant breeding
2012
Higher organisms, including plants, use three systems to initiate and sustain epigenetic gene regulation: DNA methylation, histone modification, and RNA-interference. Unraveling the relationships between these epigenetic components has led to surprising and rapidly evolving new concepts, showing how they interact and stabilize each other. These interacting systems can regulate expression or silencing of genes, resulting in epigenetically controlled phenotypes that can be meiotically or mitotically heritable. In this review we discuss issues relevant to the involvement of epigenetic inheritance as a source of polymorphism generating useful variation for selecting superior genotypes. The role of methylation in hybrid vigor and stability of performance, and aspects of epigenetic transgene silencing in elite transgenic varieties will also be addressed.
Theoretical and Applied Genetics
Crop wild relatives (CWRs) are recognized as the best potential source of traits for crop improvement. However, successful crop improvement using CWR relies on identifying variation in genes controlling desired traits in plant germplasms and subsequently incorporating them into cultivars. Epigenetic diversity may provide an additional layer of variation within CWR and can contribute novel epialleles for key traits for crop improvement. There is emerging evidence that epigenetic variants of functional and/or agronomic importance exist in CWR gene pools. This provides a rationale for the conservation of epigenotypes of interest, thus contributing to agrobiodiversity preservation through conservation and (epi)genetic monitoring. Concepts and techniques of classical and modern breeding should consider integrating recent progress in epigenetics, initially by identifying their association with phenotypic variations and then by assessing their heritability and stability in subsequent gener...
Plant epigenetics: From genomes to epigenomes
Epigenetics is the study of heritable changes in gene expression that occur without a change in the DNA sequence. In recent years, this field has attracted increasing attention as more epigenetic mechanisms affecting gene activity are being discovered. Such processes involve a complex interplay between DNA methylation, histone modifications, and non-coding RNAs, notably small interfering RNAs (siRNAs) and micro RNAs (miRNAs). Epigenetic regulation is not only important for generating differentiated cell types during plant development, but also in maintaining the stability and integrity of their respective gene expression profiles. Although epigenetic processes are essential for normal development, they can become misdirected which leads to abnormal phenotypes and diseases, especially cancer. Sensing environmental changes and initiating a quick, reversible and appropriate response in terms of modified gene expression is of paramount importance for plants which are sessile autotrophs. Although epigenetic mechanisms help to protect plant cells from the activity of parasitic sequences such as transposable elements, this defense can complicate the genetic engineering process through transcriptional gene silencing. Epigenetic phenomena have economic relevance in the case of somaclonal variation: a genetic and phenotypic variation among clonally propagated plants from a single donor genotype. The success of sequencing projects on model plants has created widespread interest in exploring the epigenome in order to elucidate how plant cell decipher and execute the information stored and encoded in the genome. New high-throughput techniques are making it easier to map DNA methylation patterns on a large scale and results have already provided surprises.