Abstract
Genome-editing has revolutionized biology. When coupled with a recently streamlined regulatory process by the U.S. Department of Agriculture and the potential to generate transgene-free varieties, genome-editing provides a new avenue for crop improvement. For heterozygous, polyploid and vegetatively propagated crops such as cultivated potato, Solanum tuberosum Group Tuberosum L., genome-editing presents tremendous opportunities for trait improvement. In potato, traits such as improved resistance to cold-induced sweetening, processing efficiency, herbicide tolerance, modified starch quality and self-incompatibility have been targeted utilizing CRISPR/Cas9 and TALEN reagents in diploid and tetraploid clones. However, limited progress has been made in other such crops including sweetpotato, strawberry, grapes, citrus, banana etc., In this review we summarize the developments in genome-editing platforms, delivery mechanisms applicable to plants and then discuss the recent developments in regulation of genome-edited crops in the United States and The European Union. Next, we provide insight into the challenges of genome-editing in clonally propagated polyploid crops, their current status for trait improvement with future prospects focused on potato, a global food security crop.
Highlights
Genome-editing technologies such as TALENs (Transcription Activator Like Effector Nucleases), CRISPR/Cas9 (Clustered Regularly Interspaced Short Palindromic Repeats/CRISPR-associated systems), CRISPR/Cas12a (Cpf1, CRISPR from Prevotella and Francisella 1), and Cas9-derived DNA base editors, provide an unprecedented advancement in genome engineering due to precise DNA manipulation
Several cultivated polyploids have vegetative mode of reproduction (Herben et al, 2017) and with allopolyploidy combined with heterozygosity makes breeding challenging in these crops
In order to introduce genetic diversity by crossing two heterozygous parents, multiple alleles segregate at a given locus
Summary
Genome-editing technologies such as TALENs (Transcription Activator Like Effector Nucleases), CRISPR/Cas (Clustered Regularly Interspaced Short Palindromic Repeats/CRISPR-associated systems), CRISPR/Cas12a (Cpf, CRISPR from Prevotella and Francisella 1), and Cas9-derived DNA base editors, provide an unprecedented advancement in genome engineering due to precise DNA manipulation. We discuss the challenges of genome-editing in clonally propagated polyploid crops and summarize the insights gained from case studies along with future prospects focused on enhancement of potato breeding using this technology. Genome-editing by sequence-specific nucleases (SSNs) such as CRISPR/Cas and TALENs facilitate targeted insertion, replacement, or disruption of genes in plants. Preassembled CRISPR/Cas or Cas12a RNP complexes were successfully delivered into protoplasts of Arabidospsis, tobacco, lettuce, rice, wheat, soybean and potato and plants were regenerated with heritable targeted mutagenesis (Woo et al, 2015; Kim et al, 2017; Liang et al, 2017; Andersson et al, 2018). Gene editing could be used to create genetic variation that is identical to that already present in crop varieties grown in Europe; it would be regulated due to this process-based approach.
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