-
1.
Engineering salinity tolerance in plants: progress and prospects.
Wani, SH, Kumar, V, Khare, T, Guddimalli, R, Parveda, M, Solymosi, K, Suprasanna, P, Kavi Kishor, PB
Planta. 2020;(4):76
Abstract
There is a need to integrate conceptual framework based on the current understanding of salt stress responses with different approaches for manipulating and improving salt tolerance in crop plants. Soil salinity exerts significant constraints on global crop production, posing a serious challenge for plant breeders and biotechnologists. The classical transgenic approach for enhancing salinity tolerance in plants revolves by boosting endogenous defence mechanisms, often via a single-gene approach, and usually involves the enhanced synthesis of compatible osmolytes, antioxidants, polyamines, maintenance of hormone homeostasis, modification of transporters and/or regulatory proteins, including transcription factors and alternative splicing events. Occasionally, genetic manipulation of regulatory proteins or phytohormone levels confers salinity tolerance, but all these may cause undesired reduction in plant growth and/or yields. In this review, we present and evaluate novel and cutting-edge approaches for engineering salt tolerance in crop plants. First, we cover recent findings regarding the importance of regulatory proteins and transporters, and how they can be used to enhance salt tolerance in crop plants. We also evaluate the importance of halobiomes as a reservoir of genes that can be used for engineering salt tolerance in glycophytic crops. Additionally, the role of microRNAs as critical post-transcriptional regulators in plant adaptive responses to salt stress is reviewed and their use for engineering salt-tolerant crop plants is critically assessed. The potentials of alternative splicing mechanisms and targeted gene-editing technologies in understanding plant salt stress responses and developing salt-tolerant crop plants are also discussed.
-
2.
CRISPR-associated nucleases: the Dawn of a new age of efficient crop improvement.
Ghogare, R, Williamson-Benavides, B, Ramírez-Torres, F, Dhingra, A
Transgenic research. 2020;(1):1-35
-
-
Free full text
-
Abstract
The world stands at a new threshold today. As a planet, we face various challenges, and the key one is how to continue to produce enough food, feed, fiber, and fuel to support the burgeoning population. In the past, plant breeding and the ability to genetically engineer crops contributed to increasing food production. However, both approaches rely on random mixing or integration of genes, and the process can be unpredictable and time-consuming. Given the challenge of limited availability of natural resources and changing environmental conditions, the need to rapidly and precisely improve crops has become urgent. The discovery of CRISPR-associated endonucleases offers a precise yet versatile platform for rapid crop improvement. This review summarizes a brief history of the discovery of CRISPR-associated nucleases and their application in genome editing of various plant species. Also provided is an overview of several new endonucleases reported recently, which can be utilized for editing of specific genes in plants through various forms of DNA sequence alteration. Genome editing, with its ever-expanding toolset, increased efficiency, and its potential integration with the emerging synthetic biology approaches hold promise for efficient crop improvement to meet the challenge of supporting the needs of future generations.
-
3.
Improving RNAi efficiency for pest control in crop species.
Yan, S, Ren, B, Zeng, B, Shen, J
BioTechniques. 2020;(5):283-290
Abstract
The application of RNAi promotes the development of novel approaches toward plant protection in a sustainable way. Genetically modified crops expressing dsRNA have been developed as commercial products with great potential in insect pest management. Alternatively, some nontransformative approaches, including foliar spray, irrigation and trunk injection, are favorable in actual utilization. In this review, we summarize the recent progress and successful cases of RNAi-based pest management strategy, explore essential implications and possibilities to improve RNAi efficiency by delivery of dsRNA through transformative and nontransformative approaches, and highlight the remaining challenges and important issues related to the application of this technology.
-
4.
Exploitation of genetic resources based on regulome and gene editing in crops.
Li, Y, Yan, W
Science China. Life sciences. 2020;(9):1406-1409
-
5.
Ultrasensitive electrochemical genosensor for detection of CaMV35S gene with Fe3O4-Au@Ag nanoprobe.
Ye, Y, Mao, S, He, S, Xu, X, Cao, X, Wei, Z, Gunasekaran, S
Talanta. 2020;:120205
Abstract
We report an attomolar sensitive electrochemical genosensor for the detection of cauliflower mosaic virus 35S (CaMV35S) gene. The sandwich-type genosensor uses gold-silver core-shell (Au@Ag)-loaded iron oxide (Fe3O4) nanocomposite (Fe3O4-Au@Ag) as label of signal DNA probe (sDNA). Electrochemical sensing is accomplished at interface of electrodeposited AuNPs and carboxylated multiwalled carbon nanotubes-modified glassy carbon electrode through the specific interaction between the capture probe and target CaMV35S (tDNA), and tDNA and the labeled sDNA. The detection sensitivity was improved by the amplified reduction signal of hydrogen peroxide (H2O2), which takes advantage of the enhanced electrocatalytic activity of Fe3O4-Au@Ag. Under the optimal experimental conditions, an ultralow limit of detection was calculated to be 1.26 × 10-17 M (S/N = 3), and the blank value subtracted reduction signal of H2O2 of the sensor increased linearly with the logarithm of CaMV35S concentration over a wide range (1 × 10-16 M to 1 × 10-10 M). This genosensor displayed excellent stability, selectivity and reproducibility, and was successful in detecting the target CaMV35S in genetically modified tomato samples.
-
6.
A critical look on CRISPR-based genome editing in plants.
Ahmad, N, Rahman, MU, Mukhtar, Z, Zafar, Y, Zhang, B
Journal of cellular physiology. 2020;(2):666-682
Abstract
Clustered regularly interspaced short palindromic repeats (CRISPR)-based genome editing, derived from prokaryotic immunity system, is rapidly emerging as an alternative platform for introducing targeted alterations in genomes. The CRISPR-based tools have been deployed for several other applications including gene expression studies, detection of mutation patterns in genomes, epigenetic regulation, chromatin imaging, etc. Unlike the traditional genetic engineering approaches, it is simple, cost-effective, and highly specific in inducing genetic variations. Despite its popularity, the technology has limitations such as off-targets, low mutagenesis efficiency, and its dependency on in-vitro regeneration protocols for the recovery of stable plant lines. Several other issues such as persisted CRISPR activity in subsequent generations, the potential for transferring to its wild type population, the risk of reversion of edited version to its original phenotype particularly in cross-pollinated plant species when released into the environment and the scarcity of validated targets have been overlooked. This article briefly highlights these undermined aspects, which may challenge the wider applications of this platform for improving crop genetics.
-
7.
Applying gene editing to tailor precise genetic modifications in plants.
Van Eck, J
The Journal of biological chemistry. 2020;(38):13267-13276
Abstract
The ability to tailor alterations in genomes, including plant genomes, in a site-specific manner has been greatly advanced through approaches that reduced the complexity and time of genome sequencing along with development of gene editing technologies. These technologies provide a valuable foundation for studies of gene function, metabolic engineering, and trait modification for crop improvement. Development of genome editing methodologies began ∼20 years ago, first with meganucleases and followed by zinc finger nucleases, transcriptional activator-like effector nucleases and, most recently, clustered regulatory interspaced short palindromic repeat (CRISPR)-associated protein (Cas) (CRISPR/Cas), which is by far the most utilized method. The premise of CRISPR/Cas centers on the cleaving of one or both DNA strands by a Cas protein, an endonuclease, followed by mending of the DNA by repair mechanisms inherent in cells. Its user-friendly construct design, greater flexibility in targeting genomic regions, and cost-effective attributes have resulted in it being widely adopted and revolutionizing precise modification of the genomes of many organisms. Indeed, the CRISPR/Cas system has been utilized for gene editing in many plant species, including important food crops, such as maize, wheat, rice, and potatoes. This review summarizes the various approaches, including the most recent designs being used to make modifications from as small as a single-base-pair change to insertion of DNA fragments. On the gene expression level, strategies are presented that make it possible to knock out or modulate through activation and repression. Also discussed are prerequisites necessary for CRISPR/Cas-mediated editing as well as the current challenges.
-
8.
Comparative analysis of genetically-modified crops: Part 1. Conditional difference testing with a given genetic background.
Jiang, C, Meng, C, Schapaugh, A
PloS one. 2019;(1):e0210747
Abstract
The European Food Safety Authority (EFSA) mandates two sets of statistical tests in the comparative assessment of a genetically-modified (GM) crop: difference testing to demonstrate whether the GM crop is different from its appropriate non-traited control; and equivalence testing to demonstrate whether it is equivalent to conventional references with an history-of-safe-use. The equivalence testing method prescribed by EFSA confounds the so-called GM trait effect with genotypic differences between the reference varieties and non-traited control. Critically, these genotypic differences, which we define as a 'control background effect', are the result of conventional plant breeding. Thus, the result of EFSA equivalence testing often has little or nothing to do with the GM trait effect, which should be the sole focus of the comparative assessment. Here, an integrated method is introduced for both difference and equivalence testing that considers the differences of the three genotype groups (GM, control, and references) as a two-dimensional random variable. A novel statistical model is proposed, called the trait model, that treats the effects of the GM and control materials as fixed for their difference, and as random for their common background. For significance testing, the covariance structure of the three genotype groups is utilized to decompose the differences into the trait effect and the control background effect. The trait difference is then derived as a conditional mean, given the background effect. The comparative assessment can then focus on the conditional mean difference, which is independent of the control background effect. Furthermore, the trait model is flexible enough to include various types of genotype-by-environment (G×E) interactions inherent to the experimental design of the trial. Numerical evaluations and simulations show that this new method is substantially more efficient than the current EFSA method in reducing both Type I and Type II errors (protecting both the consumer and producer risk) after the background effect is removed from the test statistic, and successfully addresses two major criticisms (i.e. statistical model lack of G×E, and study-specific equivalence criterion) that have been raised.
-
9.
Report on the SCRA Nuts and Bolts Workshop II: case studies of citrus greening, Ultra-low Gossypol Cotton, and blight tolerant, low-acrylamide potato.
Hood, EE, Eversole, KA, Leach, L, Hogan, M, McHughen, A, Cordts, J, Rathore, K, Rood, T, Collinge, S, Irey, M
GM crops & food. 2019;(3):139-158
-
-
Free full text
-
Abstract
To be commercialized and grown in the US, genetically engineered (GE) crops typically go through an extensive food, feed, and environmental safety assessment process which, in certain instances, requires complex consultations with three different US regulatory agencies. Many small market, niche, and specialty crops have been genetically engineered using the modern tools of recombinant DNA but few have been commercialized due to real or perceived regulatory constraints. This workshop discussed the practical aspects of developing dossiers on GE specialty, niche, or small-market crops/products for submission to US regulatory agencies. This workshop focused on actual case studies, and provided an opportunity for public or private sector scientists and crop developers to spend time with regulatory officials to learn the specifics of compiling a dossier for regulatory approval. The objective of the workshop was to explain and demystify data requirements and regulatory dossier compilation by small companies, academics, and other developers.
-
10.
Implementing an EU opt-in mechanism for GM crop cultivation.
Eriksson, D, de Andrade, E, Bohanec, B, Chatzopoulou, S, Defez, R, Leiva Eriksson, N, van der Meer, P, van der Meulen, B, Ritala, A, Sági, L, et al
EMBO reports. 2019;(5)
Abstract
A proposal for implementing an opt‐in mechanism that would allow individual member states of the EU to cultivate genetically modified crops on their territory. [Image: see text]