Solution for Plant Genome Editing and Trait Discovery by CRISPR Technology    

Genetic variation is the foundation of agricultural improvement. The purpose of plant breeding is to create and utilize these genetic variations. Throughout the long history of plant breeding, four major techniques have been utilized: cross-breeding, mutation breeding, transgenic breeding, and genome editing breeding. With the introduction of the CRISPR-Cas system, plant genome editing technology has experienced rapid development. Currently, the two main nucleases primarily used in the CRISPR-Cas system are Cas9 and Cas12a, with the recent development of the Cas12b system for plant genome editing. Base editing, a novel gene-targeting technology based on the CRISPR-Cas system, enables precise single-base modifications at target sites without inducing DNA double-strand breaks. This technology utilizes cytidine deaminases or artificially evolved adenine deaminases to achieve accurate single-base editing at target sites, enabling C-to-T or A-to-G substitutions.

Figure 1. The general process of plant genome editing.

CRISPR Technology Advancements in Mutation and Precision Breeding

Precision breeding in plants and targeted mutation have been revolutionized by the programmable gene-editing tool CRISPR-Cas9. Through precise introduction of mutations into target genes, streamlines conventional breeding. This technology directly improves complex traits while streamlining procedures such as genotyping progeny and genetic crosses. For example, modifying the ALS gene gives rice herbicide tolerance, while deleting the BADH2 gene produces aromatic rice varieties. Multiple gene loci can be edited simultaneously by CRISPR-Cas9, eliminating harmful allele burdens such as the OsERF922 gene that influences rice disease resistance. Furthermore, it breaks undesirable genetic links and promotes trait sharing amongst crops, improving the accuracy and efficiency of breeding. Breeding strategies are further optimized by utilizing endogenous gene conversion mechanisms, such as the RecQ helicase gene in wheat.

Figure 2. Cross-species trait sharing and genetic linkage breaking by genome editing-directed mutagenesis. (Gao C. et al., 2021)

CRISPR Technology for Editing Quantitative Trait Loci (QTLs)

Quantitative traits controlled by multiple genes on Quantitative Trait Loci (QTLs) pose challenges in breeding. Identifying QTLs traditionally relies on QTL mapping and genome-wide association studies (GWASs). CRISPR-Cas9 overcomes these challenges by directly introducing desired quantitative trait allele genes into elite crop varieties. It efficiently edits QTLs in low recombination regions and fine-tunes gene expression levels, balancing productivity, quality, and stress tolerance. Multiplex editing strategies modify combinations of candidate QTLs, resulting in measurable phenotypic changes.

Figure 3. Editing of quantitative trait loci to produce new alleles and traits. (Gao C. et al., 2021)

CRISPR Technology for Large-Scale Trait Discovery and Screening

Traits can be found more rapidly by characterizing genotype-phenotype connections across the genome using CRISPR-Cas9 screening. Mutants with enhanced sgRNAs are sequenced subsequent to co-expressing Cas9 and a library of sgRNAs targeting several genes. This method outperforms traditional mutagenesis procedures and may prove helpful in the future for protoplast or single-cell screening to expedite the trait-finding process.

Large-scale screening for trait engineering and discovery is made possible by CRISPR-Cas9, which introduces genes or functional domains through saturation mutagenesis. Base editors circumvent this restriction, providing the possibility of targeted evolution screening and the development of desirable traits, even though Cas9 primarily induces insertions and deletions. Future developments could broaden the application of this strategy and provide more effective and adaptable breeding techniques.

Figure 4. Large-scale screening and directed evolution for trait discovery via CRISPR. (Gao C. et al., 2021)

Plant genome editing has greatly advanced thanks to the CRISPR-Cas system, which provides accurate and effective techniques for mutation and precision breeding. Through the use of tools such as Cas9, Cas12a, and the recently developed Cas12b system, scientists are able to introduce specific mutations without causing double-strand breaks in DNA. This makes it possible to alter particular genes, giving crops better features.

In addition to offering knowledge and resources to support research and development in this area, Creative Biogene offers complete support for plant genome editing. Creative Biogene enables scientists to expedite trait discovery and breeding through a suite of CRISPR-based tools and services, such as multiplex editing and base editing. Creative Biogene's solutions enable accurate and efficient genome editing in plants, whether it's editing Quantitative Trait Loci (QTLs) or large-scale screening for desirable traits.

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