New Technologies for Insect-Resistant and Herbicide-Tolerant Plants

Genetic modification strategies for enhancing plant resilience to abiotic stresses in the context of climate change

Enhancing the resilience of plants to abiotic stresses, such as drought, salinity, heat, and cold, is crucial for ensuring global food security challenge in the context of climate change. The adverse effects of climate change, characterized by rising temperatures, shifting rainfall patterns, and increased frequency of extreme weather events, pose significant threats to agricultural systems worldwide. Genetic modification strategies offer promising approaches to develop crops with improved abiotic stress tolerance. This review article provides a comprehensive overview of various genetic modification techniques employed to enhance plant resilience. These strategies include the introduction of stress-responsive genes, transcription factors, and regulatory elements to enhance stress signaling pathways. Additionally, the manipulation of hormone signaling pathways, osmoprotectant accumulation, and antioxidant defense mechanisms is discussed. The use of genome editing tools, such as CRISPR-Cas9, for precise modification of target genes related to stress tolerance is also explored. Furthermore, the challenges and future prospects of genetic modification for abiotic stress tolerance are highlighted. Understanding and harnessing the potential of genetic modification strategies can contribute to the development of resilient crop varieties capable of withstanding adverse environmental conditions caused by climate change, thereby ensuring sustainable agricultural productivity and food security.

Mitigating Ecotoxicity Risks of Pesticides on Ornamental Plants Based on Life Cycle Assessment

Ornamental plants such as floriculture and nurseries, have become increasingly popular, but their growth relies heavily on the use of many different types of pesticides. The widespread and inefficient use of these pesticides causes environmental pollution and damage to non-target organisms. Despite these impacts, there has been little research conducted on potential agrochemical pollution in the ornamental plant industry. To address this gap, a life cycle assessment (LCA) was conducted to evaluate the pesticide-related freshwater ecotoxicity impact of the US ornamental plant industry in comparison to that of major field crops. The study analyzed 195 pesticide active ingredients used in 15 major ornamental plant and four field crops. Results showed that the freshwater ecotoxicity per area (PAF m³ d/ha) of ornamental plants was significantly higher than that of field crops due to the high pesticide intensity (kg/ha) and ecotoxicity of insecticides and fungicides used in floriculture and nurseries. To mitigate environmental stress, minimizing the use of highly toxic pesticides is recommended. A ban on low-dose, high-toxicity pesticides could reduce pesticide-driven ecotoxicity by 34% and 49% for floriculture and nursery plants, respectively. This study is among the first to quantify the pesticide-driven ecotoxicity impacts of horticultural ornamental plants and proposes feasible ways to reduce these impacts, thus making the world more sustainable while still preserving its beauty.

A versatile Agrobacterium-based plant transformation system for genetic engineering of diverse citrus cultivars

Developing an efficient transformation system is vital in genetically engineering recalcitrant crops, particularly trees. Here, we outline an Agrobacterium tumefaciens-based stable plant transformation methodology for citrus genetic engineering. The process was optimized to suit the requirements of fourteen citrus varieties by establishing appropriate infection, co-cultivation, selection, and culture media conditions. The procedure includes transforming seedling-derived epicotyl segments with an A. tumefaciens strain, then selecting and regenerating transformed tissues. Transgenic shoots were further identified by a visual reporter (e.g., β-glucuronidase) and confirmed by Northern and Southern blot analysis. Transgene integrations among the transgenic lines ranged between one to four. The methodology can yield transformation efficiencies of up to 11%, and transgenic plants can be recovered as early as six months, depending on the variety. In addition, we show that incorporating A. tumefaciens helper virulence genes (virG and virE), spermidine, and lipoic acid in the resuspension buffer before transformation improved the transformation efficiency of specific recalcitrant cultivars, presumably by enhancing T-DNA integration and alleviating oxidative stress on the explant tissues. In conclusion, the optimized methodology can be utilized to engineer diverse recalcitrant citrus varieties towards trait improvement or functional genetics applications.

Directed Evolution of Phi Class Glutathione Transferases Involved in Multiple-Herbicide Resistance of Grass Weeds and Crops

The extensive application of herbicides in crop cultivation has indisputably led to the emergence of weed populations characterized by multiple herbicide resistance (MHR). This phenomenon is associated with the enhanced metabolism and detoxifying ability of endogenous enzymes, such as phi class glutathione transferases (GSTFs). In the present work, a library of mutant GSTFs was created by in vitro directed evolution via DNA shuffling. Selected gstf genes from the weeds Alopecurus myosuroides and Lolium rigidum, and the cereal crops Triticum durum and Hordeum vulgare were recombined to forge a library of novel chimeric GSTFs. The library was activity screened and the best-performing enzyme variants were purified and characterized. The work allowed the identification of enzyme variants that exhibit an eight-fold improvement in their catalytic efficiency, higher thermal stability (8.3 °C) and three-times higher inhibition sensitivity towards the herbicide butachlor. The crystal structures of the best-performing enzyme variants were determined by X-ray crystallography. Structural analysis allowed the identification of specific structural elements that are responsible for k_cat regulation, thermal stability and inhibition potency. These improved novel enzymes hold the potential for utilization in biocatalysis and green biotechnology applications. The results of the present work contribute significantly to our knowledge of the structure and function of phi class plant GSTs and shed light on their involvement in the mechanisms of MHR.

Epigenetics and its role in effecting agronomical traits

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 underpins plant growth and dictates phenotypic responsiveness for extrinsic and intrinsic inputs. Epigenetic modifications, in addition to DNA sequence variation, improve breeding by giving useful markers. Also, it takes epigenome diversity into account to predict plant performance and increase crop production. In this review, emphasis has been given for summarising the role of epigenetic changes in epibreeding for crop improvement.

Development of Portable E-Nose System for Fast Diagnosis of Whitefly Infestation in Tomato Plant in Greenhouse

An electronic nose (E-nose) system equipped with a gas sensor array and real-time control panel was developed for a fast diagnosis of whitefly infestation in tomato plants. Profile changes of volatile organic compounds (VOCs) released from tomato plants under different treatments (i.e., whitefly infestation, mechanical damage, and no treatment) were successfully determined by the developed E-nose system. A rapid sensor response with high sensitivity towards whitefly-infested tomato plants was observed in the E-nose system. Results of principal component analysis (PCA) and hierarchical clustering analysis (HCA) indicated that the E-nose system was able to provide accurate distinguishment between whitefly-infested plants and healthy plants, with the first three principal components (PCs) accounting for 87.4% of the classification. To reveal the mechanism of whitefly infestation in tomato plants, VOC profiles of whitefly-infested plants and mechanically damaged plants were investigated by using the E-nose system and GC-MS. VOCs of 2-nonanol, oxime-, methoxy-phenyl, and n-hexadecanoic acid were only detected in whitefly-infested plants, while compounds of dodecane and 4,6-dimethyl were only found in mechanically damaged plant samples. Those unique VOC profiles of different tomato plant groups could be considered as bio-markers for diagnosing different damages. Moreover, the E-nose system was demonstrated to have the capability to differentiate whitefly-infested plants and mechanically damaged plants. The relationship between sensor performance and VOC profiles confirmed that the developed E-nose system could be used as a fast and smart device to detect whitefly infestation in greenhouse cultivation.

Herbicide Resistance: Another Hot Agronomic Trait for Plant Genome Editing

Weeds have continually interrupted crop plants since their domestication, leading to a greater yield loss compared to diseases and pests that necessitated the practice of weed control measures. The control of weeds is crucial to ensuring the availability of sufficient food for a rapidly increasing human population. Chemical weed control (herbicides) along with integrated weed management (IWM) practices can be the most effective and reliable method of weed management programs. The application of herbicides for weed control practices calls for the urgency to develop herbicide-resistant (HR) crops. Recently, genome editing tools, especially CRISPR-Cas9, have brought innovation in genome editing technology that opens up new possibilities to provide sustainable farming in modern agricultural industry. To date, several non-genetically modified (GM) HR crops have been developed through genome editing that can present a leading role to combat weed problems along with increasing crop productivity to meet increasing food demand around the world. Here, we present the chemical method of weed control, approaches for herbicide resistance development, and possible advantages and limitations of genome editing in herbicide resistance. We also discuss how genome editing would be effective in combating intensive weed problems and what would be the impact of genome-edited HR crops in agriculture.

Assessment of Glyphosate Impact on the Agrofood Ecosystem

Agro-industries should adopt effective strategies to use agrochemicals such as glyphosate herbicides cautiously in order to protect public health. This entails careful testing and risk assessment of available choices, and also educating farmers and users with mitigation strategies in ecosystem protection and sustainable development. The key to success in this endeavour is using scientific research on biological pest control, organic farming and regulatory control, etc., for new developments in food production and safety, and for environmental protection. Education and research is of paramount importance for food and nutrition security in the shadow of climate change, and their consequences in food production and consumption safety and sustainability. This review, therefore, diagnoses on the use of glyphosate and the associated development of glyphosate-resistant weeds. It also deals with the risk assessment on human health of glyphosate formulations through environment and dietary exposures based on the impact of glyphosate and its metabolite AMPA-(aminomethyl)phosphonic acid-on water and food. All this to setup further conclusions and recommendations on the regulated use of glyphosate and how to mitigate the adverse effects.

Peptide conjugated morpholinos for management of the huanglongbing pathosystem

BACKGROUND

'Candidatus Liberibacter asiaticus' (CLas) is the causal agent of the devastating citrus disease Huanglongbing (HLB) and is transmitted by the insect vector Diaphorina citri (Hemiptera: Liviidae). A potential approach for treating CLas infection is the use of synthetic nucleic acid-like oligomers to silence bacterial gene expression. Peptide conjugated morpholinos (PPMOs) targeting essential genes in CLas and the psyllid vector's endosymbiotic bacteria, Wolbachia (-Diaphorina, wDi), were evaluated using in vitro and in vivo assays.

RESULTS

Expression of the wDi gyrA gene was significantly reduced following incubation of wDi cells with PPMOs. In addition, the viability of isolated wDi cells was greatly reduced when treated with PPMOs as compared to untreated cells. Feeding D. citri adults with a complementary PPMO (CLgyrA-14) showed significantly reduced (70% lower) expression of the CLas gyrA gene. CLas relative density was significantly lower in the psyllids fed with CLgyrA-14, when compared to untreated insects. Psyllids that were treated with CLgyrA-14 were less successful in transmitting the pathogen into uninfected plants, compared to untreated insects.

CONCLUSION

The expression of essential genes in the D. citri symbiont, wDi and the HLB pathogen were suppressed in response to PPMO treatments. This study demonstrates the potential of PPMOs as a novel strategy for management of bacterial pathogens of fruit trees, such as HLB. © 2020 Society of Chemical Industry.

Distinct defensive activity of phenolics and phenylpropanoid pathway genes in different cotton varieties toward chewing pests

Identifying the maximum level of inherent defense against harmful insects in natural variation among wild lineages of crop plants may result in high yield tolerant varieties and reducing use of chemical insecticides. However, knowledge of natural cotton genotypes with high insect-resistance is still indistinguishable at the biochemical or molecular level. In the present study, different cultivated Gossypium hirsutum varieties were evaluated for their inherent insect-tolerance against two major cottons chewing pests. The insect bio-assay identified two tolerant and one susceptible cotton varieties. The study demonstrates difference in phenolic acids, proanthocyanidin and tannin accumulation in tolerant and susceptible varieties. The post-infestation of chewing pests increases transcript level of the phenylpropanoid pathway genes were detected in tolerant varieties as compared to the susceptible varieties. Altogether, chewing pest-tolerance level in cotton varieties is the cumulative effect of enhanced phenylpropanoid pathway genes expression and secondary metabolite leading to defense responses to conventional host plant.

Alternatives to neonicotinoids

The European Food Safety Authority concluded in February 2018 that "most uses of neonicotinoid insecticides represent a risk to wild bees and honeybees". In 2016, the French government passed a law banning the use of the five neonicotinoids previously authorized: clothianidin, imidacloprid, thiamethoxam, acetamiprid and thiacloprid. In the framework of an expert assessment conducted by the French Agency for Food, Environmental and Occupational Health and Safety to identify possible derogations, we performed a thorough assessment of the available alternatives to the five banned neonicotinoids. For each pest targeted by neonicotinoids use, we identified the main alternative pest management methods, which we then ranked for (i) efficacy for controlling the target pest, (ii) applicability (whether directly useable by farmers or in need of further research and development), (iii) durability (risk of resistance in targeted pests), and (iv) practicability (ease of implementation by farmers). We identified 152 authorized uses of neonicotinoids in France, encompassing 120 crops and 279 pest insect species (or genera). An effective alternative to neonicotinoids use was available in 96% of the 2968 case studies analyzed from the literature (single combinations of one alternative pest control method or product × one target crop plant × one target pest insect). The most common alternative to neonicotinoids (89% of cases) was the use of another chemical insecticide (mostly pyrethroids). However, in 78% of cases, at least one non-chemical alternative method could replace neonicotinoids (e.g. microorganisms, semiochemicals or surface coating). The relevance of non-chemical alternatives to neonicotinoids depends on pest feeding habits. Leaf and flower feeders are easier to control with non-chemical methods, whereas wood and root feeders are more difficult to manage by such methods. We also found that further field studies were required for many promising non-chemical methods before their introduction into routine use by farmers. Our findings, transmitted to policymakers, indicate that non-chemical alternatives to neonicotinoids do exist. Furthermore, they highlight the need to promote these methods through regulation and funding, with a view to reducing pesticide use in agriculture.

Nicotiana benthamiana is a suitable transient system for high-level expression of an active inhibitor of cotton boll weevil α-amylase

BACKGROUND

Insect resistance in crops represents a main challenge for agriculture. Transgenic approaches based on proteins displaying insect resistance properties are widely used as efficient breeding strategies. To extend the spectrum of targeted pathogens and overtake the development of resistance, molecular evolution strategies have been used on genes encoding these proteins to generate thousands of variants with new or improved functions. The cotton boll weevil (Anthonomus grandis) is one of the major pests of cotton in the Americas. An α-amylase inhibitor (α-AIC3) variant previously developed via molecular evolution strategy showed inhibitory activity against A. grandis α-amylase (AGA).

RESULTS

We produced in a few days considerable amounts of α-AIC3 using an optimised transient heterologous expression system in Nicotiana benthamiana. This high α-AIC3 accumulation allowed its structural and functional characterizations. We demonstrated via MALDI-TOF MS/MS technique that the protein was processed as expected. It could inhibit up to 100% of AGA biological activity whereas it did not act on α-amylase of two non-pathogenic insects. These data confirmed that N. benthamiana is a suitable and simple system for high-level production of biologically active α-AIC3. Based on other benefits such as economic, health and environmental that need to be considerate, our data suggested that α-AIC3 could be a very promising candidate for the production of transgenic crops resistant to cotton boll weevil without lethal effect on at least two non-pathogenic insects.

CONCLUSIONS

We propose this expression system can be complementary to molecular evolution strategies to identify the most promising variants before starting long-lasting stable transgenic programs.

Plant Genome Engineering for Targeted Improvement of Crop Traits

To improve food security, plant biology research aims to improve crop yield and tolerance to biotic and abiotic stress, as well as increasing the nutrient contents of food. Conventional breeding systems have allowed breeders to produce improved varieties of many crops; for example, hybrid grain crops show dramatic improvements in yield. However, many challenges remain and emerging technologies have the potential to address many of these challenges. For example, site-specific nucleases such as TALENs and CRISPR/Cas systems, which enable high-efficiency genome engineering across eukaryotic species, have revolutionized biological research and its applications in crop plants. These nucleases have been used in diverse plant species to generate a wide variety of site-specific genome modifications through strategies that include targeted mutagenesis and editing for various agricultural biotechnology applications. Moreover, CRISPR/Cas genome-wide screens make it possible to discover novel traits, expand the range of traits, and accelerate trait development in target crops that are key for food security. Here, we discuss the development and use of various site-specific nuclease systems for different plant genome-engineering applications. We highlight the existing opportunities to harness these technologies for targeted improvement of traits to enhance crop productivity and resilience to climate change. These cutting-edge genome-editing technologies are thus poised to reshape the future of agriculture and food security.

CRISPR Crops: Plant Genome Editing Toward Disease Resistance

Genome editing by sequence-specific nucleases (SSNs) has revolutionized biology by enabling targeted modifications of genomes. Although routine plant genome editing emerged only a few years ago, we are already witnessing the first applications to improve disease resistance. In particular, CRISPR-Cas9 has democratized the use of genome editing in plants thanks to the ease and robustness of this method. Here, we review the recent developments in plant genome editing and its application to enhancing disease resistance against plant pathogens. In the future, bioedited disease resistant crops will become a standard tool in plant breeding.

Metabolic engineering using iterative self-cloning to improve lipid productivity in Coccomyxa

We previously developed a self-cloning system that introduces cDNA of the uridine monophosphate synthase gene (cUMPS) of Coccomyxa sp. strain Obi as a selectable marker into uracil-auxotrophic mutants (Ura⁻) of the same alga. Here, we developed a Cre/loxP-based system for the removal of cUMPS flanked by directly repeated loxP sites from the Coccomyxa genome using the intracellular delivery of purified Cre recombinase to generate an Ura⁻ strain that was used as a host for second-round transformation using cUMPS as the selection marker. Employing this marker–gene-recycling system, Coccomyxa strains devoid of foreign DNA except the 34-bp loxP sequence, which overexpressed an acyl-(acyl-carrier-protein) thioesterase gene, and a type-2 diacylglycerol acyltransferase gene, were constructed by the sequential introduction of two expression cassettes for the respective genes. One of the resulting strains showed 1.4-fold higher lipid productivity than the wild-type strain. This method will be applicable to other eukaryotic microalgae to create marker-free transgenic strains.

Detection of exogenous double-stranded RNA movement in in vitro peanut plants

New technologies are needed to eliminate mycotoxins and/or fungal pathogens from agricultural products. RNA interference (RNAi) has shown potential to control fungi associated with crops. In RNAi, double-stranded RNA (dsRNA) targets homologous mRNA for cleavage, and can reach the mRNA of pathogens in contact with the plant. The key element in this process is the movement of RNA signals cell-to-cell and over long distances within the plant, and between host plants and parasites. In this study, we selected a regulatory gene in the aflatoxin biosynthesis pathway, aflS/aflR, necessary for the production of aflatoxins in Aspergillus spp. We designed a Dicer-substrate RNA (DsiRNA) to study the movement and stability of the duplex over time in in vitro peanut plants using stem-loop primers and RT-PCR for DsiRNA detection. The preliminary results demonstrated that DsiRNA was absorbed and moved away from the point of application, spread systemically and was transported rapidly, most likely through the phloem of the shoot, to the sink tissues, such as new auxiliary shoots, flowers and newly formed pegs. The DsiRNA remained detectable for at least 30 days after treatment. This is the first time that movement of exogenous DsiRNA in in vitro peanut plants has been described. Since DsiRNA was detectable in the pegs 15 days after treatment, aflatoxin reduction may be possible if the duplexes containing part of the aflatoxin biosynthesis pathogen gene induce silencing in the peanut seeds colonised by Aspergillus spp. The application of small RNAs could be a non-transformative option for mycotoxin contamination control.

Development of transgenic tobacco lines with pyramided insect resistant genes

Insect pests are among the major constraints rendering drastic decreases in crop yield. The expression of stacked insecticidal genes in crops can lead to resistance durability and can delay the development of resistance in target insect pests. The present study was designed to introduce an insect resistance trait in locally cultivated Turkish tobacco cultivars (Basma and Nail) with pyramided insecticidal genes. Agrobacterium strain LBA4404 harboring plasmid pKGH4 with cry1Ac and cry2A genes under the control of 35S promoter was used to infect leaf discs of both cultivars; plasmid also contained uidA within the T-DNA region for earlier screening of putative transformants. The overall transformation efficiency was calculated as 30.7% and 18.8% in Basma and Nail, respectively. PCR results confirmed the integration of cry1Ac, cry2A, uidA, and nptII genes in 40 plants of Basma and 16 plants of Nail. ELISA results showed variation in expression of cry1Ac protein among transgenic plants varying from 0.017 to 0.607 µg/g of fresh tissue. Bioassay results with potato tuber moth (Phthorimea operculella Zeller) showed significant mortality of the targeted pest on primary transformants. Furthermore, T1 transgenic progeny exhibited the inheritance of T-DNA in Mendelian as well as non-Mendelian fashion. The results revealed that lines can serve as a source of germplasm in tobacco breeding programs.

Editing the Genome Without Double-Stranded DNA Breaks

Genome editing methods have commonly relied on the initial introduction of double-stranded DNA breaks (DSBs), resulting in stochastic insertions, deletions, and translocations at the target genomic locus. To achieve gene correction, these methods typically require the introduction of exogenous DNA repair templates and low-efficiency homologous recombination processes. In this review, we describe alternative, mechanistically motivated strategies to perform chemistry on the genome of unmodified cells without introducing DSBs. One such strategy, base editing, uses chemical and biological insights to directly and permanently convert one target base pair to another. Despite its recent introduction, base editing has already enabled a number of new capabilities and applications in the genome editing community. We summarize these advances here and discuss the new possibilities that this method has unveiled, concluding with a brief analysis of future prospects for genome and transcriptome editing without double-stranded DNA cleavage.

Expression characterization of the herbicide tolerance gene Aryloxyalkanoate Dioxygenase (aad-1) controlled by seven combinations of regulatory elements

BACKGROUND

Availability of well characterized maize regulatory elements for gene expression in a variety of tissues and developmental stages provides effective alternatives for single and multigene transgenic concepts. We studied the expression of the herbicide tolerance gene aryloxyalkanoate dioxygenase (aad-1) driven by seven different regulatory element construct designs including the ubiquitin promoters of maize and rice, the actin promoters of melon and rice, three different versions of the Sugarcane Bacilliform Badnavirus promoters in association with other regulatory elements of gene expression.

RESULTS

Gene expression of aad-1 was characterized at the transcript and protein levels in a collection of maize tissues and developmental stages. Protein activity against its target herbicide was characterized by herbicide dosage response. Although differences in transcript and protein accumulation were observed among the different constructs tested, all events were tolerant to commercially relevant rates of quizalafop-P-ethyl compared to non-traited maize under greenhouse conditions.

DISCUSSION

The data reported demonstrate how different regulatory elements affect transcript and protein accumulation and how these molecular characteristics translate into the level of herbicide tolerance. The level of transcript detected did not reflect the amount of protein quantified in a particular tissue since protein accumulation may be influenced not only by levels of transcript produced but also by translation rate, post-translational regulation mechanisms and protein stability. The amount of AAD-1 enzyme produced with all constructs tested showed sufficient enzymatic activity to detoxify the herbicide and prevent most herbicidal damage at field-relevant levels without having a negative effect on plant health.

CONCLUSIONS

Distinctive profiles of aad-1 transcript and protein accumulation were observed when different regulatory elements were utilized in the constructs under study. The ZmUbi and the SCBV constructs showed the most consistent robust tolerance, while the melon actin construct provided the lowest level of tolerance compared to the other regulatory elements used in this study. These data provide insights into the effects of differing levels of gene expression and how these molecular characteristics translate into the level of herbicide tolerance. Furthermore, these data provide valuable information to optimize future designs of single and multiple gene constructs for maize research and crop improvement.

Purification and characterization of trypsin produced by gut bacteria from Anticarsia gemmatalis

Purification of active trypsin in the digestive process of insects is essential for the development of potent protease inhibitors (PIs) as an emerging pest control technology and research into insect adaptations to dietary PIs. An important aspect is the presence of proteolytic microorganisms, which contribute to host nutrition. Here, we purified trypsins produced by bacteria Bacillus cereus, Enterococcus mundtii, Enterococcus gallinarum, and Staphylococcus xylosus isolated from the midgut of Anticarsia gemmatalis. The trypsins had a molecular mass of approximately 25 kDa. The enzymes showed increased activity at 40°C, and they were active at pH values 7.5-10. Aprotinin, bis-benzamidine, and soybean Kunitz inhibitor (SKTI) significantly inhibited trypsin activity. The l-1-tosyl-amido-2-phenylethylchloromethyl ketone (TPCK), pepstatin A, E-64, ethylenediamine tetraacetic acid, and calcium ions did not affect the enzyme activity at the concentrations tested. We infer the purified trypsins do not require calcium ions, by which they differ from the trypsins of other microorganisms and the soluble and insoluble trypsins characterized from A. gemmatalis. These data suggest the existence of different isoforms of trypsin in the velvetbean caterpillar midguts.

Induced plant defences in biological control of arthropod pests: a double-edged sword

Biological control is an important ecosystem service delivered by natural enemies. Together with breeding for plant defence, it constitutes one of the most promising alternatives to pesticides for controlling herbivores in sustainable crop production. Especially induced plant defences may be promising targets in plant breeding for resistance against arthropod pests. Because they are activated upon herbivore damage, costs are only incurred when defence is needed. Moreover, they can be more specific than constitutive defences. Nevertheless, inducible defence traits that are harming plant pest organisms may interfere with biological control agents, such as predators and parasitoids. Despite the vast fundamental knowledge on plant defence mechanisms and their effects on natural enemies, our understanding of the feasibility of combining biological control with induced plant defence in practice is relatively poor. In this review, we focus on arthropod pest control and present the most important features of biological control with natural enemies and of induced plant defence. Furthermore, we show potential synergies and conflicts among them and, finally, identify gaps and list opportunities for their combined use in crop protection. We suggest that breeders should focus on inducible resistance traits that are compatible with the natural enemies of arthropod pests, specifically traits that help communities of natural enemies to build up. © 2017 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

New Biotechnological Tools for the Genetic Improvement of Major Woody Fruit Species

The improvement of woody fruit species by traditional plant breeding techniques has several limitations mainly caused by their high degree of heterozygosity, the length of their juvenile phase and auto-incompatibility. The development of new biotechnological tools (NBTs), such as RNA interference (RNAi), trans-grafting, cisgenesis/intragenesis, and genome editing tools, like zinc-finger and CRISPR/Cas9, has introduced the possibility of more precise and faster genetic modifications of plants. This aspect is of particular importance for the introduction or modification of specific traits in woody fruit species while maintaining unchanged general characteristics of a selected cultivar. Moreover, some of these new tools give the possibility to obtain transgene-free modified fruit tree genomes, which should increase consumer's acceptance. Over the decades biotechnological tools have undergone rapid development and there is a continuous addition of new and valuable techniques for plant breeders. This makes it possible to create desirable woody fruit varieties in a fast and more efficient way to meet the demand for sustainable agricultural productivity. Although, NBTs have a common goal i.e., precise, fast, and efficient crop improvement, individually they are markedly different in approach and characteristics from each other. In this review we describe in detail their mechanisms and applications for the improvement of fruit trees and consider the relationship between these biotechnological tools and the EU biosafety regulations applied to the plants and products obtained through these techniques.

MicroRNAs in crop improvement: fine-tuners for complex traits

One of the most common challenges for both conventional and modern crop improvement is that the appearance of one desirable trait in a new crop variety is always balanced by the impairment of one or more other beneficial characteristics. The best way to overcome this problem is the flexible utilization of regulatory genes, especially genes that provide more efficient and precise regulation in a targeted manner. MicroRNAs (miRNAs), a type of short non-coding RNA, are promising candidates in this area due to their role as master modulators of gene expression at the post-transcriptional level, targeting messenger RNAs for cleavage or directing translational inhibition in eukaryotes. We herein highlight the current understanding of the biological role of miRNAs in orchestrating distinct agriculturally important traits by summarizing recent functional analyses of 65 miRNAs in 9 major crops worldwide. The integration of current miRNA knowledge with conventional and modern crop improvement strategies is also discussed.

Review. Development, Applications, Benefits, Challenges and Limitations of the New Genome Engineering Technique. An Update Study

We assume that the CRISPR Cas9 theory must be delimited by applicability, because the consequences of long term DNA manipulation remain unknown. Moreover, the irreversibility of this procedure should instigate researchers to reserved opinions.

Usefulness as well as benefits of CRISPR Cas9 made it one of the most popular and used genome editing technique. But with its huge potential, ethical and safety concerns emerge. Therefore, before continuing research in this direction we should have a well organized system that is able to make that differentiation between research and reproduction. However we truly believe in the future of genetic engineering and with the CRISPR-Cas9 system we expect that the opportunity of treating now so called incurable diseases arises. Time is all we need.

Trends and Challenges in Pesticide Resistance Detection

Pesticide resistance is a crucial factor to be considered when developing strategies for the minimal use of pesticides while maintaining pesticide efficacy. This goal requires monitoring the emergence and development of resistance to pesticides in crop pests. To this end, various methods for resistance diagnosis have been developed for different groups of pests. This review provides an overview of biological, biochemical, and molecular methods that are currently used to detect and quantify pesticide resistance. The agronomic, technical, and economic advantages and drawbacks of each method are considered. Emerging technologies are also described, with their associated challenges and their potential for the detection of resistance mechanisms likely to be selected by current and future plant protection methods.

Genome editing: intellectual property and product development in plant biotechnology

Genome editing is a revolutionary technology in molecular biology. While scientists are fascinated with the unlimited possibilities provided by directed and controlled changes in DNA in eukaryotes and have eagerly adopted such tools for their own experiments, an understanding of the intellectual property (IP) implications involved in bringing genome editing-derived products to market is often lacking. Due to the ingenuity of genome editing, the time between new product conception and its actual existence can be relatively short; therefore knowledge about IP of the various genome editing methods is relevant. This point must be regarded in a national framework as patents are instituted nationally. Therefore, when designing scientific work that could lead to a product, it is worthwhile to consider the different methods used for genome editing not only for their scientific merits but also for their compatibility with a speedy and reliable launch into the desired market.

Enhancing Plant Disease Resistance without R Genes

Crop plants encounter constant biotic challenges, and these challenges have historically been best managed with resistance (R) genes. However, the rapid evolution of new pathogenic strains along with the nonavailability or nonidentification of R genes in cultivated crop species against a large number of plant pathogens have led researchers to think beyond R genes. Biotechnological tools have shown promise in dealing with such challenges. Technologies such as transgenerational plant immunity, interspecies transfer of pattern recognition receptors (PRRs), pathogen-derived resistance (PDR), gene regulation, and expression of antimicrobial peptides (AMPs) in host plants from other plant species have led to enhanced disease resistance and increased food security.

Restoration, Reintroduction, and Rewilding in a Changing World

The increasing abandonment of marginal land creates new opportunities for restoration, reintroduction, and rewilding, but what do these terms mean in a rapidly and irreversibly changing world? The 're' prefix means 'back', but it is becoming clear that the traditional use of past ecosystems as targets and criteria for success must be replaced by an orientation towards an uncertain future. Current opinions in restoration and reintroduction biology range from a defense of traditional definitions, with some modifications, to acceptance of more radical responses, including assisted migration, taxon substitution, de-extinction, and genetic modification. Rewilding attempts to minimize sustained intervention, but this hands-off approach is also threatened by rapid environmental change.