**7.2 Gene silencing**

Gene silencing is a method of down regulating (or 'turning off') specific genes via the over expression of RNA sequences (RNAi), which prevents a gene's functional expression. Even though it has been available for many years, it is increasingly being used as a method for shutting off specific genes. Future food protection applications may involve shutting off pathogen attack receptors or stress response elements, which could be extremely useful in the face of climate change. Gene editing is a technique for making precise, targeted changes in genomes at a scale of one or a few nucleotides. Using clustered regularly interspaced short palindromic repeats (CRISPR) and the CAS9 nuclease, transcriptional activator-like effectors' nucleases (TALEN), two alternative systems currently provide state-of-the-art protocols for achieving these small-scale genomic adjustments. Precise genomic modification using CRISPR has been likened to a 'find and replace' function [26]. To precision edit genomes, TALENS employs a nuclease system based on the fusion of transcription

activator-like effectors with target DNA binding domains and an endonuclease cleavage domain. Variable DNA binding domain sequences, like CRISPR/CAS9, enable different genomic targets to be addressed. In rice and wheat, the TALENS system has been effective in conferring powdery mildew resistance [27].

To monitor plant responses or stimulate pathogen resistance, RNA spraying technology topically applies complex synthetic RNA to surfaces, such as plant leaves. RNA spraying technology is known to be under investigation by a number of agricultural biotechnology firms. Since there is no alteration to the plant genome, RNA spraying eliminates the need for genetic modification in such applications. Instead, plant cells take up the sprayed synthetic RNA, temporarily silencing specific genes before the effect wears off, which can take anywhere from a few days to three months [28].

#### **8. Use of genetic resources for climate smart crop**

The sustainable use of plant genetic resources can help in adapting and mitigating the effects of climate change.

#### **8.1 Genetic resources for climate change adaptation: a sustainable use**

The sustainable utilization of plant genetic assets includes evaluation of genetic traits; identification of desirable traits; plant breeding, including epigenomics; variations in crop production; advancement and commercialization of hybrids; sustainable seed production and supply chain system; and establishment of new business sectors for the distribution of local varieties and related products. These exercises can play a key role to address the effects of climate change on sustainable crop production.

The sustainable utilization of plant genetic assets includes evaluation of genetic traits; identification of desirable traits; plant breeding, including epigenomics; variations in crop production; advancement and commercialization of hybrids; sustainable seed production and supply chain system; and establishment of new business sectors for the distribution of local varieties and related products. These exercises can play a key role to address the effects of climate change on sustainable crop production.

In their local production environments, farmer varieties and landraces are well adapted to current conditions and proved to be a successful source for adaptive genes in crop improvement [29]. However, they may lose this adaptation in the changing climatic conditions [30]. It may not be a practical solution to introduce more suitable crop varieties from elsewhere [31]. For this purpose, the only viable solution may be the breeding of new varieties. More genetic vulnerability renders crop potentially more susceptible to the impact of climate change. By incorporating novel traits into cultivars, this genetic vulnerability may be reduced. These novel traits are often found in wild relatives of the crops [32]. Pre-breeding is a source of introduction novel alleles from wild cultivars into crop varieties [33]. In this technique, intermediate materials are generated that are used as parents in plant breeding. Diversity and geographical locations of crop wild relatives and landraces can remotely be determined by using predictive characterization tools based on eco-geographic and climate data [34]. This method is known as the Focused Identification of Germplasm Strategy. In the changing climatic conditions, it would be a challenge for breeders and geneticists to increase the yields of major food crops or even maintain them that will definitely depend on their ability to improve local varieties by introducing adaptive traits through breeding [35]. It is also of

#### *Climate Smart Crops for Food Security DOI: http://dx.doi.org/10.5772/intechopen.99164*

much importance for the farmer community to actively participate in the varietal development process to increase the adoption rates of new varieties [36]. Use of a wide range of methodologies is required to develop crop varieties that are tolerant toward climate change induced stresses [37]. These methodologies include induced mutations, biotechnological applications, including cell and tissue biology, marker assisted selection and genetic engineering; and novel plant breeding techniques, including genome editing procedures. With the help of such techniques, Scuba Rice, a flood-tolerant variety of rice was developed for the flood prone areas, such as those found in Bangladesh, India and the Philippines. This is an excellent example of the successful breeding of a crop variety that supports climate-smart agriculture. In these areas where such extreme challenges are faced by crops, adoption of climate-ready varieties is expected to increase because of climate change. There are many neglected and underutilized edible plant species that are resilient and adapted to marginal areas [38]. For example, Moringa (Moringa oleifera), Yam bean (Pachyrhizuserosus) and Bambara groundnut (Vigna subterranea) etc. It would be strategically important to replace staple crops such as maize, with droughtresistant crops, such as cassava and millets in drought-prone regions of the world. However, this climate-smart agricultural adaptation strategy would only be possible if farmers are willing to adopt these new crops. Farmers can only get benefit from this strategy if the seed and planting materials of such crops are available in right quantity and quality and at an acceptable cost. The effectively availability of such resources is much important for these diverse crops and crop varieties to contribute to climate change adaptation and sustain rural livelihoods [39]. Variety approval and release procedures, seed production, quality control, and its marketing are important components of seed delivery systems. These systems usually fall under national and international policies and regulations, that involve diverse actors, such as government authorities, community-level cooperatives, private firms, input dealers, and contracted growers.
