CRISPR-Cas9 Mutations in a Rice Gene Changes Starch Biosynthesis in the Endosperm

Scientists from University of Lleida-Agrotecnio Center and partners aimed to alter the starch biosynthetic machinery of rice using CRISPR-Cas9 to introduce mutations affecting the Waxy (Wx) locus encoding granule-bound starch synthase I (GBSSI) in rice endosperm. Mutation of genes in the starch biosynthetic pathway has a significant impact on starch quality and quantity.

CRISPR-Cas9 mutations lead to the reduction, but not elimination of the GBSS activity in the seeds. It was reported that the GBSS activity in the mutants was 61–71% of wild-type levels, similarly to two irradiation mutants, but the amylose content was reduced to 8–12% in heterozygous seeds and to as low as 5% in homozygous seeds. Abnormal cellular organization in the aleurone layer and amorphous starch grain structures were also observed. The expression of other genes involved in starch production was modulated in seeds and leaves, which resulted in the changes in AGPase and sucrose synthase activity which explained the corresponding starch and soluble sugar concentrations.

Read the research article in Plant Cell Reports.