CRISPR/Cas9 genome editing tool for rice crop improvement

Abstract

Food crop yield, quality, and tolerance mechanisms to biotic and abiotic factors are important aspects that contribute to food security. To feed about 10 billion people by 2050, high yielding climate-resilient rice cultivars with good grain quality must be created more quickly. Yield and quality, along with stress tolerance traits of the rice crop, have been improved by adopting various methods. Among these, in recent years, the yield of the crop has been improved marginally by utilizing conventional breeding methods. Mutation breeding is an important pathway that has created many novel variations and contributed towards isolating new high yielding genotypes in the rice crop. Forward and reverse genetic protocols have been engaged for the identification of genomic variants in conventional mutation breeding to characterize the novel variants to convert as functional markers for the development of new improved varieties. Generation of desired mutations in the desirable region of the genome of the crops is highly tedious through conventional breeding methods such as random mutagenesis since the gene manipulations happen randomly while the mutagenesis is done using physical and chemical mutagens. Also, it requires large mutant plant populations to isolate the desired mutants and mutations. The advancement of CRISPR/Cas9 genome editing technology rapidly replaces conventional random mutagenesis technologies, has the ability to multiplex genome editing to create novel variations for crop improvement programs, and reduces the time duration required for trait based crop improvement programs. In this review, significant gene manipulations employed through CRISPR/Cas9 for rice crop improvement in terms of yield and biotic and abiotic stress tolerance are discussed.