CRISPR/Cas9 Mediated Genome Engineering for Improvement of Horticultural Crops

Abstract

Horticultural crops are an important part of agriculture for food as well as nutritional security. However, several pests and diseases along with adverse abiotic environmental factors pose a severe threat to these crops by affecting their quality and productivity. This warrants the effective and accelerated breeding programs by utilizing innovative biotechnological tools that can tackle aforementioned issues. The recent technique of genome editing by Clustered Regularly Interspaced Short Palindromic Repeats/CRISPR associated 9 (CRISPR/Cas9) has greatly advanced the breeding for crop improvement due to its simplicity and high efficiency over other nucleases such as Zinc Finger Nucleases and Transcription Activator Like Effector Nucleases. CRISPR/Cas9 tool contains a non-specific Cas9 nuclease and a single guide RNA that directs Cas9 to the specific genomic location creating double-strand breaks and subsequent repair process creates insertion or deletion mutations. This is currently the widely adopted tool for reverse genetics, and crop improvement in large number of agricultural crops. The use of CRISPR/Cas9 in horticultural crops is limited to few crops due to lack of availability of regeneration protocols and sufficient sequence information in many horticultural crops. In this review, the present status of applicability of CRISPR/Cas9 in horticultural crops was discussed along with the challenges and future potential for possible improvement of these crops for their yield, quality, and resistance to biotic and abiotic stress.

Perspectives of CRISPR/Cas-mediated cis-engineering in horticulture: unlocking the neglected potential for crop improvement

“…We need to continuously improve horticultural commodities to meet the rising demand for food and ornamental production. The widespread applications of CRISPR/Cas technologies in horticultural crops open the possibility for accelerating new variety development [12][13][14][15][16][17] . Engineering cis-regulatory regions using CRISPR/Cas allows the creation of novel variants, resulting in quantitative variation, and thus holds great potential for creating phenotypic diversity.…”

“…Despite the importance of regulatory changes in genes, the application of CRISPR/ Cas-mediated cis-engineering has only been explored sporadically. The genome sequence for at least 181 horticultural species is available 11 and genome editing has been used to generate primarily knockout mutations in at least 25 of them [12][13][14][15][16][17] . These achievements demonstrate the feasibility of applying CRISPR/Cas-mediated cisengineering to expand the phenotypic diversity of many horticultural crops.…”

CRISPR for Crop Improvement: An Update Review

“…CRISPR/Cas9 mediated genome editing is also being applied for the improvement of horticulturally important crops such as vegetable and fruit crops for enhancing the shelf life, yield and disease resistance. Increasing data availability through whole genome sequencing and transcriptome sequencing of important horticultural crops will enhance the application of CMGE for crop improvement ( Karkute et al, 2017 ). A recent review by Sattar et al (2017) describes the possibilities and challenges of CMGE in date palm which is an important fruit crop.…”

Status and Contribution of CRISPR/Cas9 Based Gene-Editing System in the Development of a Low-Immunogenic Wheat Variety

“…The main concept behind the genome editing techniques is to employ engineered endonucleases to make sitespecific DNA Double-Strand Break (DSB), which triggers the cellular intrinsic DSB repair mechanism to repair the breaks [21]. These repairs can be tricked to add, remove, or substitute a series of nucleotides in the genetic code, thus enabling the introduction of known desired alleles in the target organism [22]. The major DNA DSB repair mechanisms include Non-Homologous End Joining (NHEJ) and Homologous Recombination (HR) [19,23].…”