ABSTRACT
Since it was first recognized in bacteria and archaea as a mechanism for innate viral immunity in the early 2010s, clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR-associated protein (Cas) has rapidly been developed into a robust, multifunctional genome editing tool with many uses. Following the discovery of the initial CRISPR/Cas-based system, the technology has been advanced to facilitate a multitude of different functions. These include development as a base editor, prime editor, epigenetic editor, and CRISPR interference (CRISPRi) and CRISPR activator (CRISPRa) gene regulators. It can also be used for chromatin and RNA targeting and imaging. Its applications have proved revolutionary across numerous biological fields, especially in biomedical and agricultural improvement. As a diagnostic tool, CRISPR has been developed to aid the detection and screening of both human and plant diseases, and has even been applied during the current coronavirus disease 2019 (COVID-19) pandemic. CRISPR/Cas is also being trialed as a new form of gene therapy for treating various human diseases, including cancers, and has aided drug development. In terms of agricultural breeding, precise targeting of biological pathways via CRISPR/Cas has been key to regulating molecular biosynthesis and allowing modification of proteins, starch, oil, and other functional components for crop improvement. Adding to this, CRISPR/Cas has been shown capable of significantly enhancing both plant tolerance to environmental stresses and overall crop yield via the targeting of various agronomically important gene regulators. Looking to the future, increasing the efficiency and precision of CRISPR/Cas delivery systems and limiting off-target activity are two major challenges for wider application of the technology. This review provides an in-depth overview of current CRISPR development, including the advantages and disadvantages of the technology, recent applications, and future considerations.
Subject(s)
Humans , CRISPR-Cas Systems , Clustered Regularly Interspaced Short Palindromic Repeats , Crops, Agricultural/genetics , Gene Editing/methods , Genetic Therapy , Nobel Prize , Plant BreedingABSTRACT
In the era of climate change, due to increased incidences of a wide range of various environmental stresses, especially biotic and abiotic stresses around the globe, the performance of plants can be affected by these stresses. After oxygen, silicon (Si) is the second most abundant element in the earth's crust. It is not considered as an important element, but can be thought of as a multi-beneficial quasi-essential element for plants. This review on silicon presents an overview of the versatile role of this element in a variety of plants. Plants absorb silicon through roots from the rhizospheric soil in the form of silicic or monosilicic acid. Silicon plays a key metabolic function in living organisms due to its relative abundance in the atmosphere. Plants with higher content of silicon in shoot or root are very few prone to attack by pests, and exhibit increased stress resistance. However, the more remarkable impact of silicon is the decrease in the number of seed intensities/soil-borne and foliar diseases of major plant varieties that are infected by biotrophic, hemi-biotrophic and necrotrophic pathogens. The amelioration in disease symptoms are due to the effect of silicon on a some factors involved in providing host resistance namely, duration of incubation, size, shape and number of lesions. The formation of a mechanical barrier beneath the cuticle and in the cell walls by the polymerization of silicon was first proposed as to how this element decreases plant disease severity. The current understanding of how this element enhances resistance in plants subjected to biotic stress, the exact functions and mechanisms by which it modulates plant biology by potentiating the host defence mechanism needs to be studied using genomics, metabolomics and proteomics. The role of silicon in helping the plants in adaption to biotic stress has been discussed which will help to plan in a systematic way the development of more sustainable agriculture for food security and safety in the future.
Subject(s)
Silicon , Stress, Physiological , Plants , Soil , AgricultureABSTRACT
RNA interference (RNAi) is a powerful tool for gene silencing in different organisms, including plants. It isbeing used in functional genomics to decipher the function of genes. This technology has also witnessed avariety of potential applications in agriculture for crop improvement, including the development of crops forresistance against biotic (weeds, pathogens, insect pests and nematode parasites) and abiotic stresses (drought,high and low temperature, etc.), nutritional quality improvement, healthier oils, delayed ripening, male sterility,modification of flowering time and flower colour, alteration of plant architecture, enhancement of secondaryproducts, and removal of allergens and toxins. RNAi has several advantages over traditional transgenicapproaches as genetically modified RNAi plants do not contain transgene protein, however the risk assessmentof these plants should be examined to rule out any off-target effects.
ABSTRACT
Crop improvement is a continuous effort, since some 10,000 years ago when primitive man made the transitionfrom hunting and foraging to domestication and crop cultivation. Since then, man-made interventions havechanged the entire scenario of crop evolution, by means of genetic alterations of plants and animals made tosatisfy man’s needs. The process of domestication has led to dramatic changes in their appearance, quality andproductivity that have contributed substantially to global food security. The tremendous decline in cultivableland, freshwater, and increasing risk of biotic and abiotic stress demand immediate attention on cropimprovement to cope with the higher demand of *40% of the food by 2020. Therefore, plant genetic variationplays a key role in plant breeding for its improvement. Most of the genetic variations useful for cropimprovement have been deposited and maintained in seed gene banks across the world; they need to be broughtinto the mainstream of breeding lines. Recent advances and progress made in molecular markers have beensubstantial tools for deeper insights of genetics, and greatly complemented breeding strategies. Integration of thenext-generation sequencing (NGS) technologies with precise phenotyping, association mapping, proteome andmetabolome studies has increased the chances of finding candidate genes and their allelic variants controlling atrait of interest. Further, these functional markers (FMMs), genotype-by-sequencing and association mappingmethodologies have opened new avenues for identification of novel genetic resources (lines) that can facilitateaccelerated crop breeding programs for increased yield, high nutritional quality, and tolerance to a variety ofabiotic and biotic stresses. The details of popular molecular markers, advancement in the technologies andstrategies for crop diversity studies and their application in crop breeding programs are presented here.
ABSTRACT
The rice blast caused by the fungus Magnaporthe oryzae is one of the most devastating diseases of rice and can lead to complete failure of the crop under severe cases. The first step in breeding for blast resistance in rice is therefore to identify the novel sources of resistance and cataloguing different blast resistant genes in these genotypes. In the present study, a set of 37 rice genotypes comprising of landraces, advanced breeding lines and released varieties were first characterized for blast resistance under epiphytotic conditions and subsequently different blast resistant genes were catalogued with the help of markers tightly linked to these genes. A total of 22 different blast resistant genes were catalogued in these genotypes. Lot of diversity was found to be present for different genes in the rice genotypes studied. In addition, a set of 2–3 markers were identified which could distinguish genotypes of a particular geographic area from each other.The results are useful for identifying the right combination of genotypes in the resistance breeding programme
ABSTRACT
Domestication of rice involved incorporation of specific yield-related changes in wild species of rice. This agriculturalprocess has been of significant interest for plant biologists. The recent advance in genomics has provided new tools toinvestigate the genetic basis and consequences of domestication. Several genes involved in domestication and diversification process have been characterized, and as expected, this list is over-represented by transcription factors and their cofactors. Most often the modification orchestrated expression levels of genes such as those coding for transcription factors. Ithas been proposed that transcriptional regulators and their regulation is likely a major theme controlling morphologicaldifferences between crops and their progenitors. However, recent data indicate that single amino acid changes in genescoding for key proteins as well as epigenetic and small RNA-mediated pathways also contributed towards domesticationassociated phenotypes.
ABSTRACT
Andrographis paniculata (Burm. f.) Nees (AP) is commonly used for the treatment of many infectious diseases and has been cultivated widely in Asian countries, and has been included in United States Pharmacopoeia as a dietary supplement, but the cultivars of A. paniculata are not abundant due to its self-pollinated. With the aims to enrich AP resources and provide materials for after breeding we explored the polyploidy induction. Different explants, colchicine concentration, and treatment time were tested. After identification by flow cytometry, eleven polyploid plants with different morphologic traits were obtained. The agronomic traits and andrographolide concentration of the polyploids were improved greatly. One of the polyploids (serial 3-7) was chosen for further study. The traits of the second and third generation polyploids (serial 3-7) were stable. Compared with the normal plants, the seeds (2nd generation) weight increased by 31%, and the andrographolide concentration of the leaves increased by 14% (2nd) and 28% (3rd). In conclusion, AP autopolyploids with different morphologic traits were established successfully for the first time, and the polyploids induction might be effective for crop improvement of AP.
Subject(s)
Andrographis , Chemistry , Genetics , Breeding , Cell Culture Techniques , Plant Extracts , Chemistry , PolyploidyABSTRACT
Andrographis paniculata (Burm. f.) Nees (AP) is commonly used for the treatment of many infectious diseases and has been cultivated widely in Asian countries, and has been included in United States Pharmacopoeia as a dietary supplement, but the cultivars of A. paniculata are not abundant due to its self-pollinated. With the aims to enrich AP resources and provide materials for after breeding we explored the polyploidy induction. Different explants, colchicine concentration, and treatment time were tested. After identification by flow cytometry, eleven polyploid plants with different morphologic traits were obtained. The agronomic traits and andrographolide concentration of the polyploids were improved greatly. One of the polyploids (serial 3-7) was chosen for further study. The traits of the second and third generation polyploids (serial 3-7) were stable. Compared with the normal plants, the seeds (2nd generation) weight increased by 31%, and the andrographolide concentration of the leaves increased by 14% (2nd) and 28% (3rd). In conclusion, AP autopolyploids with different morphologic traits were established successfully for the first time, and the polyploids induction might be effective for crop improvement of AP.
Subject(s)
Andrographis , Chemistry , Genetics , Breeding , Cell Culture Techniques , Plant Extracts , Chemistry , PolyploidyABSTRACT
A protocol for high frequency production of somatic embryos was worked out in pigeonpea, Cajanus cajan (L.) Millsp. The protocol involved sequential employment of embryogenic callus cultures, low density cell suspension cultures and a novel microdroplet cell culture system. The microdroplet cell cultures involved culture of a single cell in 10 µl of Murashige and Skoog’s medium supplemented with phytohormones, growth factors and phospholipid precursors. By employing the microdroplet cell cultures, single cells in isolation were grown into cell clones which developed somatic embryos. Further, 2,4-dichlorophenoxyacetic acid, kinetin, polyethylene glycol, putrescine, spermine, spermidine, choline chloride, ethanolamine and LiCl were supplemented to the low density cell suspension cultures and microdroplet cell cultures to screen for their cell division and somatic embryogenesis activity. Incubation of callus or the inoculum employed for low density cell suspension cultures and microdroplet cell cultures with polyethylene glycol was found critical for induction of somatic embryogenesis. Somatic embryogenesis at a frequency of 1.19, 3.16 and 6.51 per 106 cells was achieved in the callus, low density cell suspension cultures and microdroplet cell cultures, respectively. Advantages of employing microdroplet cell cultures for high frequency production of somatic embryos and its application in genetic transformation protocols are discussed.