Fig. 4.

PpEMS1 and PpTPD1 (from moss Physcomitrella patens) function as Arabidopsis EMS1 and TPD1 in Arabidopsis, respectively. a PpEMS1 and PpTPD1 completely restored the phenotypes of ems1 and tpd1, respectively. b Analyses of the expression levels of the transgenes in the inflorescences of the corresponding plants shown in a. Proteins with GFP tag were detected with anti-GFP antibody. Actin served as the loading control. PpTPD1 expression levels were detected by semi-quantitative RT-PCR, ACT2 served as an internal control. c Co-expressing PpEMS1 and PpTPD1 under the BRI1 promoter partially rescued bri1 phenotypes. Phenotypes of 4-week-old Col-0, PpEMS1-1 & PpTPD1 and PpEMS1-2 & PpTPD1 in Col-0 and bri1-116 mutants were shown, respectively. Scale bar, 2 cm. d Analyses of the expression levels of the transgenes in the inflorescences of the corresponding plants shown in c. Proteins with GFP tag were detected with anti-GFP antibody. Actin served as the loading control. PpTPD1 expression levels were detected by semi-quantitative RT-PCR. ACT2 served as an internal control. e Co-expressing PpEMS1 and PpTPD1 under the BRI1 promoter in Col-0 and bri1-116 induced BES1 dephosphorylation. Phosphorylated BES1 (pBES1) and dephosphorylated BES1 were detected with BES1 antibodies in the extracts of 10-day-old seedlings of the indicated genotypes. Actin served as the loading control. f, g 5-day-old dark-grown seedlings in 1/2 MS medium with or without 5 μM BRZ. Scale bar, 1.5 cm. n = 10 seedlings. **P < 0.0001 (two-way ANOVA with Sidak’s test). Co-expressing PpEMS1-1 & PpTPD1 and PpEMS1-2 & PpTPD1 in Col-0 or bri1-116 showed less sensitivity or  insensitivity to BRZ, respectively. h A proposed model illustrating that EMS1 and BRI1 have evolved distinct extracellular domains to control different biological processes but can act via a common intracellular signaling pathway