A New Era in Molecular Biology: CRISPR/Cas9 and Targeted Genome Editing
The development of efficient and reliable ways to make precise, targeted changes to the genome of living cells is a long-standing goal for biomedical researchers. Recently, a new tool based on a bacterial CRISPR-associated protein-9 nuclease (Cas9) from Streptococcus pyogenes has generated considerable excitement. This follows several attempts over the years to manipulate gene function, including homologous recombination and RNA interference (RNAi). RNAi became a laboratory staple enabling inexpensive and high-throughput interrogation of gene function but it is hampered by providing only temporary inhibition of gene function and unpredictable off-target effects. Other recent approaches to targeted genome modification – zinc-finger nucleases (ZFNs), and transcription-activator like effector nucleases (TALENs) enable researchers to generate permanent mutations by introducing doublestranded breaks to activate repair pathways. These approaches are costly and time-consuming to engineer, limiting their widespread use, particularly for large scale, high-throughput studies
The functions of CRISPR (Clustered Regularly Interspaced Short Palindromic Repeats) and CRISPR-associated (Cas) genes are essential in adaptive immunity in select bacteria and archaea, enabling the organisms to respond to and eliminate invading genetic material. These repeats were initially discovered in the 1980s in E. coli, but their function wasn’t confirmed until 2007 by Barrangou and colleagues, who demonstrated that S. thermophilus can acquire resistance against a bacteriophage by integrating a genome fragment of an infectious virus into its CRISPR locus. Three types of CRISPR mechanisms have been identified, of which type II is the most studied. In this case, invading DNA from viruses or plasmids is cut into small fragments and incorporated into a CRISPR locus amidst a series of short repeats (around 20 bps). The loci are transcribed, and transcripts are then processed to generate small RNAs (crRNA – CRISPR RNA), which are used to guide effector endonucleases that target invading DNA based on sequence complementarity.
This book highlights the implications of nanotechnology and the effects of nanoparticles on agricultural systems, their interactions with plants as well as their potential applications as fertilizers and pesticides. It also discusses how innovative, eco-friendly approaches to improve food and agricultural systems lead to increased plant productivity. Further, it offers insights into the current trends and future prospects of nanotechnology along with the benefits and risks and their impact on agricultural ecosystems. Nanomaterials in agriculture reduce the amount of chemical products sprayed by means of smart delivery of active ingredients; minimize nutrient losses in fertilization; and increase yields through optimized water and nutrient management. There is also huge potential for nanotechnology in the provision of state-of-the-art solutions for various challenges faced by agriculture and society, both today and in the future.
Nanotechnology for Enhancing Crop Productivity
Suresh Kaushik and S.R. Djiwanti
Agriculture is currently facing a number of challenges like low nutrient use efficiency, stagnation in crop yields, multi-nutrient deficiencies, climate change, and water availability. One of the frontier technologies like nanotechnology can be explored to detect precisely and supply the accurate quantity of plant nutrients and pesticides to enhance crop productivity in agriculture. Nanotechnology involves the designing, production, characterization and application of devices, structures, and systems by controlling the size and shape at nanometer scale. Nanotechnology using nanodevices and nanomaterials provides new avenues for potential novel applications in agriculture such as efficient delivery of pesticide and fertilizer using nanomaterial-based formulations such as nano-fertilizers, nano-pesticides, and nano-herbicides. New innovative smart delivery systems and sensitive nano-biosensor-based technology have great potential to solve the problems faced in crop production. This chapter summarizes some new developments in smart delivery systems and nano biosensor-based technology for enhancing crop productivity.
Book title: Plant Macronutrient Use Efficiency: Molecular and Genomic Perspectives in Crop Plants
Editors: Mohammad Anwar Hossain, Takehiro Kamiya, David J. Burrit, Lam-Son Phan Tran and Toru Fujiwara
Publisher: Academic Press, Elsevier
The term “Hindu” as explained by Dr.S. Radhakrishnan in his famous book entitled ” The Hindu view of Life”. Dr. S. Radhakrishnan was an Indian philosopher and statesman. He was the second President of India from 1962 and 1967.
Many of anthropogenic activities modified the nutrient cycles of major and micro nutrients of worlds. The scale of these changes has massively accelerated since the industrial revolution throwing the equilibrium into disarray. Mineral nutrients such as nitrogen, phosphorous potassium, calcium, magnesium, sulphur, and other micronutrients are essential for plant growth and crop production. Presently, we face a glaring contrast of insufficient use of nutrients on one hand and excessive use on another. Nutrients Use efficiency (NUE) represents a key indicator to assess progress towards better nutrient management. Fertilizers are chemical compounds applied to promote plant growth. It is applied either through the soil or by foliar feeding. Artificial fertilizers are inorganic fertilizers formulated in approximate concentration to supply the nutrients. Nitrogen is an important source which is essential for the growth of plant. Urea is the most wildly used water soluble plant nitrogen source. Due to leaching the nitrogen content in the soil get decreased leading to low nitrogen utilization efficiency. Nitrogen-use efficiency for most crops ranges from 30 to 50 percent, so researchers are developing intelligent nano-fertilizers to reduce the amount of nitrogen lost during the crop production. The plant needs different amount of nitrogen depending on its growth stage. A new generation of fertilizers will increase this efficiency from 30 percent to upwards of 80 percent. The idea is to develop a product that will release nitrogen only when the plant needs it and in the amount the plant needs. The plants communicate their surroundings environment by producing all kinds of chemical signals. A plant synthesizes specific compounds to communicate with specific microbes. The microbes then go to work and free nitrogen that the plant uses to grow. Thus, roots send out signal that ask microbes to transform nitrogen in the soil into a chemical form the plant can use. Many chemical compounds that are associated with nitrogen uptake have been identified. These compounds can be used to synchronize the release of fertilizer with nitrogen uptake by the crop. Similarly, a plant under attack by insects or soil pathogen triggers defense mechanisms that synthesize alkaloids or antibiotics emitted into the surrounds soil to defense itself. A biosensor is a device that combines a biological recognition element with a physical or chemical transducer to detect a biological product. In other words, it is a probe that integrates a biological one with an electronic component to yield a measurable signal. Several biosensors are being developed for different applications. Typically a biosensor consists of three components: the biological recognition element, the transducer and the signal processing electronics. Nano-biosensors that will bind to these compounds can be developed so as to control of the release of fertilizers. The polymers coatings that protects the fertilizers from the elements contains nano-sized biosensors which are made up of very specific chemical compounds that allow the fertilizers to be released into the soil when the plant needs it. These biosensors know when to release nitrogen because they are able to detect chemical signals released from the roots of the plant to the soil. Biosensors can detect when a plant requires more nitrogen and allow microbes access to the fertilizer-nitrogen inside the polymer protected particles. As mentioned earlier that each plant species sends out its own variety of chemical signals. Keeping this concept in mind, an intelligent nano-fertilizer product could be tailored to respond differently to the needs of different crops. For instance, the nitrogen particles could be designated to become available to wheat, but not to the canola growing in the same field because of different compounds emitted by different crops. We can prepare different biosensors using different compounds and tailor the fertilizers to each different crop for different climatic zones and soils. Dr. Carlos Montreal of Agriculture and Agri-Food Canada in Ottawa is one of the several research scientists developing a fertilizer that responds to organic compounds emitted by a plant’s roots. The research team is trying to make intelligent fertilizers with the biodegradable three-dimensional polymer coating less than 100 nm thick. Nitrogen-use efficiency for most crops ranges from 30 to 50 percent. Intelligent nano-fertilizers could be used to reduce the amount of nitrogen lost during the crop production. The plant needs different amount of nitrogen depending on its growth stage. A new generation of smart fertilizers will increase this efficiency from 30 percent to upwards of 80 percent. Smart biosensors and smart delivery systems will help in enhancing productivity in agriculture. Hence, in coming years farmers could have access to an intelligent nano-fertilizer that synchronizes the release of nitrogen with crop uptake.