Comparison of the dgs1-2 T-DNA null allele and the dgs1-1 point mutant gain-of-function allele in wild-type (WT) and dgd1 backgrounds. A, Genotyping of wild-type (1) and dgs1-2 homozygous (2) plants using the PCR primers RP, LP, and LB1 described under “Materials and Methods.” B, Diagram showing the relative positions of the dgs1-1 and dgs1-2 mutations in the DGS1 protein. The relative positions of two predicted transmembrane-spanning domains are also indicated (TM1 and TM2). C, Growth phenotypes of 30-d-old plants sown directly on soil. The respective genotypes are indicated along the bottom.