Figure 1.

Genetic Screen to Identify Dnr Phenotypes.

(A) Crossing scheme. Predicted maternal-to-paternal genomic ratio in the endosperm (m:p) are indicated. 2m:1p and 4m:2p ratios result in normal endosperm development, while 2m:2p results in an abortive endosperm and defective kernels.

(B) Ear phenotypes of wild-type and mutant females. R, Seeds containing putatively reduced gametes; UR, seeds containing putatively unreduced gametes.

(C) Flow cytometry analysis of embryos from Dnr4 × tetraploid ears dissected from defective (left) and normally developed kernels (right; in green, with the embryo dissected from defective kernels in blue as a control). The defective kernels contained triploid embryos (3×), while the plump kernels contained tetraploid embryos (4×), most likely originating from unreduced female gametes.

(D) Flow cytometry analysis of pollen ploidy in Dnr4 plants. Identical results were obtained for four independent plants with a Dnr4 female phenotype.