Regularly interspaced short palindromic repeats/cas9 system (CRISPR-Cas)
is a well-developed and frequently used genome editing system, which comprises a
Cas9 nuclease and a single-guided RNA (that is an RNA-guided technique). Cas9
recognizes and cuts a specific DNA sequence by base-pairing with it, generating
double-strand breakage (DSBs) that initiate cellular DNA repair mechanisms that result
in alterations in the DSB regions or adjacent. CRISPR/Cas9 technology has
transformed genetic modifications since its inception, and it is now routinely used to
improve the genomics of large numbers of crops. CRISPR/Cas system is used for
targeted modifications to improve plant growth, yield and tolerance to biotic and
abiotic stress along with developing transgene-free gene-edited crops. The limitations
of using the CRISPR/Cas9 technology, as well as ways for enhancing its
responsiveness, are also investigated. This chapter also describes the introduction of
CRISPR-edited DNA-free plants, which may be more acceptable than some other
genetically-engineered organisms. The prospective uses of the CRISPR/Cas9
technology, as well as conventional breeding possibilities, are highlighted in this
introductory chapter.
Keywords: CRISPR/Cas9, Conventional breeding, Genome editing, Geneticallyengineered organisms.