*3.7. BR-Induced Lamina Joint Inclination Assay*

The BR-induced lamina joint inclination assay was performed as previously described with some modifications [93]. Sterilized seeds of WT and the *osbhlh079-D* mutant were grown on Murashige and Skoog (MS) medium in an artificial growth chamber at 30 ◦C under dark conditions for 10 days. Then, the 2-cm lamina joint segments of WT and *osbhlh079-D* were excised, and incubated on distilled water containing various concentrations of 24-epibrassinolide (BL), an active form of brassinosteroid (Sigma), at 30 ◦C in darkness for 48 h. The angle between lamina and sheath was measured using ImageJ software [94].
