Double Mutation of Days to Heading 2 and CONSTANS 3 Improves Agronomic Performance of Japonica Rice under Short Daylight Conditions in Southern China.

Some progress has been made in understanding the pathways related to rice heading, but their applications to breeding rice varieties adapted to grow in low-latitude areas (" to ") are limited. We edited eight adaptation-related genes via a lab-established CRISPR/Cas9 system in a variety, Shennong265 (SN265). All T plants and their progeny bearing random mutation permutations were planted in southern China and screened for changes in heading date. We found that the double mutant of 2 () and () (-), two () genes, showed significantly delayed heading under both short-day (SD) and long-day (LD) conditions in Guangzhou and manifested great yield increase under SD conditions. We further demonstrated that the heading-related - pathway was down-regulated in the - mutant lines. The editing of the genes and greatly improves the agronomic performance of rice in Southern China.