*4.3. Development of Transgene-Free Mutant Lines*

To obtain homozygous transgene-free mutants, T1 seedlings were foliar-sprayed with 1000 mg/<sup>L</sup> bentazon (approximately 100 mL/m2) at about the four-leaf stage according to a previous study [38]. At least five surviving T1 plants from each independent T0 plants were selected for further analysis of the presence of T-DNA and site-specific mutations. Eventually, four *OsITPK6* mutant lines (*ositpk6\_1*, *\_2*, *\_3*, and *\_4*) (Figure 1A) were identified; the T2 and advanced-generation seeds were used for the experiments.
