Scientists from the Indonesian Center for Agricultural Biotechnology and Genetic Resources Research and Development (ICABIOGRAD) reported the targeted mutation of the GA20ox-2 gene using the CRISPR-Cas9 system which led to the development of semi-dwarf rice plants. The findings are published in IOP Science.
GA20ox-2 is a gene encoding an oxidase enzyme involved in the biosynthesis of gibberellin and linked to sd1 locus. In a previous investigation, it was found that the mutation of this gene leads to shorter plants due to defects in the gibberellin signaling pathway. Thus, ICABIOGRAD researchers used CRISPR-Cas9 for targeted mutation of the gene in rice with the expression of two guide RNAs (gRNAs).
The team introduced a single plasmid vector of the CRISPR-Cas9 system harboring dual gRNAs to modify OsGA20ox-2 gene in rice cultivar Kitaake through Agrobacterium-mediated transformation. Results showed a mutation efficiency of 90%. Half of the mutated lines had mutations in both OsGA20ox-2 gRNAs. They observed diallelic mutation with 44 base pair deletions, while three lines were heterozygous, one line was homo-diallelic with 2 base pair insertion, and one line had no mutation. The mutated rice lines exhibited semi-dwarfism, which confirms the disruption of OsGA20ox-2.