Plant breeding at the speed of light: the power of CRISPR/Cas to generate directed genetic diversity at multiple sites

Abstract

Classical plant breeding was extremely successful in generating high yielding crop varieties. Yet, in modern crops, the long domestication process has impoverished the genetic diversity available for breeding. This is limiting further improvements of elite germplasm by classical approaches. The CRISPR/Cas system now enables promising new opportunities to create genetic diversity for breeding in an unprecedented way. Due to its multiplexing ability, multiple targets can be modified simultaneously in an efficient way, enabling immediate pyramiding of multiple beneficial traits into an elite background within one generation. By targeting regulatory elements, a selectable range of transcriptional alleles can be generated, enabling precise fine-tuning of desirable traits. In addition, by targeting homologues of so-called domestication genes within one generation, it is now possible to catapult neglected, semi-domesticated and wild plants quickly into the focus of mainstream agriculture. This further enables the use of the enormous genetic diversity present in wild species or uncultured varieties of crops as a source of allele-mining, widely expanding the crop germplasm pool.

Metabolic Engineering a Model Oilseed Camelina sativa for the Sustainable Production of High-Value Designed Oils

“…The CRISPR/Cas9 gene editing has evolved as the most powerful tool for efficient and specific genome engineering to create genetic models for both fundamental research and crop genetic improvements although this new technology is being developed rapidly (Shan et al, 2013;Van Campenhout et al, 2019;Wolter et al, 2019). This gene editing system has been successfully used to generate a broad range of stable mutagenesis at specific locus in several important crops such as rice (Zhang et al, 2014), wheat , maize (Svitashev et al, 2015), soybean , tomato (Ito and Nakano, 2015), potato (Butler et al, 2015), FIGURE 4 | Strategy redesigning biosynthetic pathways for w-7 FAs production in common oil seeds.…”

“…As CRISPR/Cas9 advance for targeted genome editing in recent years (Wolter et al, 2019), this tool makes it possible to introduce the assembled transgene modules into specific loci in the host crop, leading to an enhancement in the predictability of transgenesis and metabolic outcomes. Like the cases discussed above, CRISPR/Cas9 was used to "knock out" or disable the target gene in the competing pathways so as to direct metabolic flux toward the desired route.…”

In planta gene targeting can be enhanced by the use of CRISPR/Cas12a

“…The emergence of the CRISPR/Cas technology enabled targeted double‐strand break (DSB) induction at high efficiency in a simple way (Jinek et al ., ; Le Cong et al ., ). Since then, a broad range of new applications of the technology is currently transforming plant biology (Baltes et al ., ; Malzahn et al ., ; Puchta, ; Kumlehn et al ., ; Langner et al ., ; Chen et al ., ; Sedeek et al ., ; Wolter et al ., ). The stimulatory potential of targeted DSB induction for non‐homologous end‐joining (NHEJ)‐mediated gene knockout and homologous recombination (HR)‐mediated gene targeting (GT) in plants was already demonstrated long before the development of CRISPR/Cas (Puchta et al ., ; Salomon and Puchta, ).…”

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

“…These changes appear to have been selected during domestication, resulting in desirable traits caused by altered gene expression 3,5 . The CRISPR/Cas-based platform offers a powerful tool by engineering cis-regulatory regions (cis-engineering) to introduce genetic diversity that could potentially accelerate crop improvement [6][7][8][9][10] . Despite the importance of regulatory changes in genes, the application of CRISPR/ Cas-mediated cis-engineering has only been explored sporadically.…”