The CRISPR/Cas Genome-Editing Tool: Application in Improvement of Crops

Abstract

The Clustered Regularly Interspaced Short Palindromic Repeats associated Cas9/sgRNA system is a novel targeted genome-editing technique derived from bacterial immune system. It is an inexpensive, easy, most user friendly and rapidly adopted genome editing tool transforming to revolutionary paradigm. This technique enables precise genomic modifications in many different organisms and tissues. Cas9 protein is an RNA guided endonuclease utilized for creating targeted double-stranded breaks with only a short RNA sequence to confer recognition of the target in animals and plants. Development of genetically edited (GE) crops similar to those developed by conventional or mutation breeding using this potential technique makes it a promising and extremely versatile tool for providing sustainable productive agriculture for better feeding of rapidly growing population in a changing climate. The emerging areas of research for the genome editing in plants include interrogating gene function, rewiring the regulatory signaling networks and sgRNA library for high-throughput loss-of-function screening. In this review, we have described the broad applicability of the Cas9 nuclease mediated targeted plant genome editing for development of designer crops. The regulatory uncertainty and social acceptance of plant breeding by Cas9 genome editing have also been described. With this powerful and innovative technique the designer GE non-GM plants could further advance climate resilient and sustainable agriculture in the future and maximizing yield by combating abiotic and biotic stresses.

CRISPR/CAS9 as a Powerful Tool for Crop Improvement

“…1). The resulting product is expected to be identical to the classically bred plants (Giddings et al 2012;Khatodia et al 2016).…”

Revisiting Domestication to Revitalize Crop Improvement: The Florigen Revolution

“…sgRNAs (single guide RNAs) are targeted to specific locations in the plant genome and Cas9 nuclease recognizes the sgRNA and protospace adjacent motif (PAM) sequences, resulting in a double-stranded break (Sander and Joung 2014;Khatodia et al 2016). Using these engineered nucleases, the CRISPR/ Cas9 system has been broadly expanded to gene knockout, DNA replacement, multiplex editing, and transcription modulation in plants (Sander and Joung 2014).…”

“…In the tomato antiflorigen mutant "self pruning", the perennial sympodial growth has been altered to give an annual determinate sympodial growth habit, and recently, tomato florigen studies reporting sft/+ heterosis and a florigen activation dosage model have suggested new techniques for post-domestication of tomato in both the field and greenhouse (Pnueli et al 1998;Krieger et al 2010;Jiang et al 2013;Park et al 2014b). Moreover, CRISPR/Cas9 genome editing technology provides breeders with an innovative technique for crop improvement, including that of edible wild species (Khatodia et al 2016). In this review, we summarize how new discoveries on florigen pathways integrating flowering time genes have been utilized for the most recent domestications in order to improve crop yields.…”

Use of Crispr/Cas9 for Development of Disease Resistant Cultivars in Plant Breeding

“…The segregation of the transgene in F1 generation prevents undesirable modification from CRISPR/Cas9 in further generation. The selection of transgene-free homozygous plants with resistant genes in F1 generation helps in further breeding of plants to develop cultivars resistant to specific viral, bacterial and pestdisease (Khatodia et al, 2016) (Fig. 3).…”

“…This technique creates mutation in the target DNA with removal of target sequence and addition of gene of interest. It helps in mutagenesis of inaccessible genes, multi gene editing and generate large gene deletion which ultimately helps in progressive plant breeding (Khatodia, Bhatotia, Passricha, Khurana & Tuteja, 2016). This precise modification intro a plant genome can be inherited stably and the Cas9/sgRNA transgene can be removed to make the plants transgene free for successive improvement of the crop variety in further generations (Xu et al, 2015; Fig.…”