*2.2. OsbHLH079 Increases Grain Length in Rice*

In addition to their increased leaf angle, *osbhlh079-D* plants produced long grains (Figure 3a). The grain length of *osbhlh079-D* was longer than WT, while the grain width and grain thickness of *osbhlh079-D* were smaller, resulting in no significant difference in 500-grain weight between WT

and *osbhlh079-D* (Figure 3b). To confirm if the long grain phenotype of *osbhlh079-D* is caused by the overexpression of *OsbHLH079*, we compared the grain length among WT, *35S::OsbHLH079*, and *35S::RNAi-OsbHLH079*. The grain lengths of two independent *35S::OsbHLH079* lines were much longer than WT, whereas the grain lengths of two independent *35S::RNAi-OsbHLH079* lines were significantly shorter than WT (Figure 3c,d). Collectively, these results suggested that *OsbHLH079* is also involved in the regulation of grain length in rice.

**Figure 3.** The grain phenotypes of WT, *osbhlh079-D*, *35S::OsbHLH079*, and *35S::RNAi-OsbHLH079*. (**a**) Unhulled and hulled grain phenotypes of the *osbhlh079-D* mutant compared to those of WT. Scale bar = 0.5 cm. (**b**) Comparison of grain length, grain width, grain thickness, and 500-grain weight between WT and the *osbhlh079-D* mutant. Means and standard deviations were obtained from twenty biological replicates. Asterisks indicate statistically significant differences (\* *p* < 0.05, \*\* *p* < 0.01, Student's *t*-test) compared to WT. NS, not significant. (**c**) The unhulled grain phenotype of *35S::OsbHLH079* (upper panel), and *35S::RNAi-OsbHLH079* (lower panel) compared to that of WT. Scale bar = 0.5 cm. (**d**) Statistical analysis of grain lengths among the WT, *35S::OsbHLH079 #2*, *35S::OsbHLH079 #12*, *35S::RNAi-OsbHLH079 #4*, and *35S::RNAi-OsbHLH079 #5*. Means and standard deviations were obtained from twenty biological replicates. Significant differences between means were analyzed using Student's *t*-test (\* *p* < 0.05, \*\* *p* < 0.01). These experiments were repeated twice with similar results.
