The scope of transformation and genome editing for quantitative trait improvements in rice

Abstract Conventional methods of transformation for crop improvement and functional studies using Agrobacterium tumefaciens are still the method of choice, even though genotype specificity in indica rice can cause poor efficiencies of cell regeneration into transgenic plants. In such cases, tissue culture-independent in planta transformation using Agrobacterium has been shown to be highly effective to produce transgenic plants. Transient transformation using both biolistics and Agrobacterium has paved the way for rapid functional assays of genes or determining the efficacy of promoter sequences. However, biolistics or RNP-mediated delivery of gene editing components using CRISPR-Cas technology is more advantageous over Agrobacterium-mediated transformation methods because the foreign components get quickly degraded after nucleotide changes have taken place. For the Agrobacterium-mediated gene editing method, at least 2–3 generations are required to select only for mutations without the gene editing components. In all cases, however, gene editing can produce improved rice and other crop varieties without the “transgenic tag.” Crop improvement has been achieved for many biotic and abiotic tolerance traits as well as yield enhancement, which are cited here. Advances in gene sequencing technologies and the management of public databases with information on many new germplasm resources mean that many novel traits can now be incorporated for tailor-made crops to defend against threats to food security from increasing population and climate change.