Field Crop 2025, Vol.8, No.2, 72-81 http://cropscipublisher.com/index.php/fc 75 particular, and Wang et al. (2021) have encountered poor targeting efficiency. When it comes to improving rapeseed quality, the solution proposed by Tian et al. (2022) is more reliable, which is to optimize the transformation process and combine it with strict screening standards. Figure 2 Schematic of gene editing using CRISPR-Cas9 inB. napus (Adopted from Zhang et al., 2019) Image caption: a Single-gRNA (upper) and multi-gRNA (lower) mediated gene editing in B. napus. E, editing; N-E, non-editing. b Single-gRNA mediated target for knockout at CRISPR-Cas9-mediated cleavage. Sequencing results in chrA07 are listed in g1 lines, g2 lines and g3 lines, respectively, and in the common site of g4 lines. c Multi-gRNA-mediated target for knockout at CRISPR-Cas9-mediated cleavage. “-” and “+” indicate nucleotide insertions and deletions in the target sequence, while “s” indicates substituted mutations, and “c” indicates combined mutations. The pentagram in red indicates insertions in the target site. gRNAs are coloured yellow, whereas PAMs are coloured green (Adopted from Zhang et al., 2019) 4 Expected Impact on Oleic Acid Content and Oil Quality 4.1 Changes in fatty acid composition following CRISPR editing CRISPR/Cas9 is indeed a good way to increase the oleic acid content of rapeseed, but the effect depends on how it is edited. For example, Liu et al. (2022) found that if only one site, BnFAD2, was edited, the oleic acid ratio was less than 80%, but if both A5 and C5 sites were changed at the same time, the T1 and T4 generations could exceed 85%-this gap is quite obvious. The data of Huang et al. (2020) are similar. The wild-type oleic acid is only 66.43%. After all copies of BnaFAD2 are mutated, it directly rises to more than 80%. But the role of CRISPR/Cas9 is not only to increase oleic acid, but also to reduce those not-so-good fatty acids. Shi et al. (2022) found that after knocking out BnFAD2 and BnFAE1, the erucic acid content decreased significantly, and polyunsaturated fatty acids (PUFA) also decreased a little. Jiang et al. (2017) also tried this on domesticated rapeseed (Camelina sativa). Once the FAD2 gene was edited, linoleic acid and linolenic acid were
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