**4. Conclusions**

We found that OsbHLH079 increases leaf angle and grain length in rice. Rice overexpressing *OsbHLH079* (*osbhlh079-D* and *35S::OsbHLH079*) showed wider leaf angle and longer grain length, and RNA-mediated knockdown lines of *OsbHLH079* (*35S::RNAi-OsbHLH079*) exhibited narrower leaf angle and shorter grain length compared to those of WT. Our data also revealed that OsbHLH079 enhances BR signaling by modulating the expression levels of BR signaling-related genes (*OsBZR1, ILI1*, and *DLT*) which lead to increases in leaf angle and grain length. This study opens up the possibility to improve grain yield per unit area in rice by controlling plant architecture and seed shape.

#### **Supplementary Materials:** Supplementary materials can be found at http://www.mdpi.com/1422-0067/21/6/2090/s1.

**Author Contributions:** B.-D.L. and N.-C.P. designed and supervised the research. H.S., S.-H.K., and J.-H.L. performed the experiments and analyzed data. S.-H.K. and S.-J.L. performed the revision experiments. G.A. developed *osbhlh079-D* mutant and provided critical advice. H.S., S.-H.K., B.-D.L., and N.-C.P. wrote the manuscript. All authors have read and agreed to the published version of the manuscript.

**Funding:** This research was supported by grants from the Next-Generation BioGreen21 Program (PJ013656 to B.-D.L.), Rural Development Administration, and the Basic Science Research Program through the National Research Foundation (NRF) of Korea funded by the Ministry of Education (NRF-2017R1A2B3003310 to N.-C.P.), Republic of Korea.

**Conflicts of Interest:** The authors have no potential conflicts of interest.
