Production of Two Elite Glutinous Rice Varieties by Editing Wx Gene

The waxy gene (Wx) in rice, which encodes the granule bound starch synthase enzyme, is responsible for amylose synthesis. Glutinous (sticky) rice has little or no amylose that can be used in various applications, such as brewing. In this study, knockout of the Wx gene with CRISPR/Cas9 technology was conducted in two elite japonica rice lines, Huaidao 5 (HD5) and Suken 118 (SK118), aiming to develop elite sticky rice varieties. We achieved six homozygous T-0 plants with more than 200 bp deletion in the Wx gene, as well as 36 wx-HD5 and 18 wx-SK118 homozygous transgene-free plants in the T-1 generation. The seeds of all the mutants were white and opaque, similar to those of sticky rice, and contained only 2.6%-3.2% amylose. Results of scanning electron microscopy showed that the quality of rice did not change. In conclusion, we successfully developed two elite sticky rice varieties.