ANR, LR, and primary root phenotyping assays

For root phenotyping assays, seedlings were vertically grown on half-strength MS [with 0.5% sucrose + 1% agar and MES (0.5 g/liter) (pH 5.7)] media. Anchor roots (ANRs), located in root-hypocotyl junction, were counted in 8 dps seedlings using a dissection microscope. To investigate ANR after root excision (ANR-RE), RAM of seedlings was excised using sterile scalpels at 5 dps and then grown for another 3 days before counting. Protocol for quantifying LR capacity has been described previously (doi: 10.1073/pnas.1403016111). Specifically, RAM of seedlings were excised at 8 dps and then grown for another 3 days before counting the number of emerged LRs. Primary root length was measured using the publicly available ImageJ software (http://rsbweb.nih.gov/ij/) after taking digital photographs