**3. Results**

### *3.1. Agronomic Traits and Seed Characteristics of Namil(SA)-flo1*

The major agronomic and yield-related traits of the Namil(SA)-flo1 mutant and the corresponding Namil wild type were analyzed in plants grown under paddy field conditions. Compared with the wild type, heading was delayed by 3 days and CL was extended by 4 cm in the Namil(SA)-flo1 mutant. Panicle size, tiller number, and spikelets per panicle did not di ffer significantly between the wild type and Namil(SA)-flo1 mutant, but RGP was lower in Namil(SA)-flo1 than in the wild type (Table 1).



a Means with the same letter are not significantly different at *p* < 0.05 in the least significant difference test (LSD0.05). b The means of each line were obtained from replicated yield trials with three replication plots. HD: days-to-heading after sowing, CL: culm length, PL: panicle length, TN: tiller number, SN: spikelet number per panicle, RGP: ripened grains percentage.

Cross-sectional observation of dehulled kernels revealed that most of the Namil(SA)-flo1 endosperm was white–opaque, except for a thin peripheral area (Figure 1a). SEM showed that the Namil(SA)-flo1 endosperm contained numerous small starch grains of irregular and rounded

shapes that were more loosely packed than in the wild type. The wild-type endosperm exhibited densely packed starch granules of polyhedral angular shapes (Figure 1b). In contrast with the appearance of the grain and the endosperm in Namil, Namil(SA)-flo1 exhibited a milky-white opaque endosperm. No differences in grain width, length, or thickness were observed between the mutant and the wild type (Figure 1c).

**Figure 1.** Phenotypic analyses of the mutant Namil(SA)-flo1 and wide type Namil. (**a**) Brown rice and transverse sections of Namil(SA)-flo1 and Namil; (**b**) Electron microscope visualization of mature endosperm. The Namil(SA)-flo1 is packed loosely with compound starch granules; (**c**) The grains' shape and weight (TGW: 1000-grain weight of brown rice).

The flour physicochemical properties were also examined. The results show that the flour derived from the mutant grains was significantly lighter than that from the wild-type grains. The ash content was lower in Namil(SA)-flo1 than in the wild type. The amylose content was comparable between the wild type and Namil(SA)-flo1, but the lipid content was higher and the protein content was significantly lower in Namil(SA)-flo1 than in the wild type (Table 2). These findings are consistent with the results of previous reports showing that increasing the lipid content could cause a floury endosperm [12].
