Fig. 6.

Phosphorylation state of MYB3R3 is associated with protein accumulation and zeocin response. a Confocal microscopy images of myb3r3 root tips harbouring ProMYB3R3::MYB3R3AAA-GFP or ProMYB3R3::MYB3R3DDD-GFP. Five-day-old seedlings were treated with or without 2 μM zeocin, or with 50 μM MG132, for 24 h. Scale bars, 100 μm. b Protein level of MYB3R3-GFP in roots. Ten-day-old myb3r3 seedlings harbouring ProMYB3R3::MYB3R3-GFP (WT), ProMYB3R3::MYB3R3AAA-GFP (AAA) or ProMYB3R3::MYB3R3DDD-GFP (DDD) were treated with or without 2 μM zeocin for 24 h, and 40 µg of total protein extracted from roots was immunoblotted with anti-GFP or anti-histone H3 antibodies. Protein extract from myb3r3 was used as a control. Relative levels of MYB3R3-GFP are expressed as the fold change, normalized with respect to the band of histone H3. c Eighteen-day-old seedlings of WT, myb3r3 and myb3r3 carrying ProMYB3R3::MYB3R3AAA-GFP or ProMYB3R3::MYB3R3DDD-GFP. Scale bars, 2 cm. d, e Root growth of WT, myb3r3 and myb3r3 carrying ProMYB3R3::MYB3R3-GFP, ProMYB3R3::MYB3R3AAA-GFP or ProMYB3R3::MYB3R3DDD-GFP. Five-day-old seedlings were transferred to medium with or without 2 µM zeocin, and root length was measured for 6 days d. Root length after 6 days of zeocin treatment is shown in e. Data are presented as mean ± SD (n > 30). Significant differences from WT were determined by Student’s t-test: *P < 0.05; **P < 0.01; ***P < 0.001