Knockdown of AtCTF7results in growth defects and sterility. The RNAi mediated down-regulation of AtCTF7 results in growth inhibition, female and male gametophyte defects, and sterility. (A,B) Loss of coloration and growth inhibition in treated (B) compared to untreated (A) AtCTF7-RNAi seedlings. (C) Impaired growth and sterile siliques in treated (right) compared to untreated (left) AtCTF7-RNAi adult plants. (D,E) Alexander staining of mature anthers shows loss of pollen viability (green grains instead of purple) in treated (E) compared to untreated (D) AtCTF7-RNAi mature anthers. (F,G) Scanning electron micrograph of anther from untreated (F) and treated (G) AtCTF7-RNAi plant showing reduction of pollen grains following treatment. (H-J) Impaired female gametophyte and ovule development in treated ( I,J ) compared to untreated (H) AtCTF7-RNAi plants. (I) Ovule lacking a female gametophyte. (J) Ovule with abnormal integument development. (K) Quantification of female gametophytic and ovule defects shown in (I) and (J) for ovule stages 3–4 to 3–6 . Gametophytes were classified as uninucleate (1N), binucleate (2N), missing (nes), or wild type (WT) if they contained greater than 2 nuclei. ai: ovules showing abnormal integument development. (L,M) DAPI staining of mature pollen grains reveals loss of chromatin in the male gametophyte of treated (M) compared to untreated (L) AtCTF7-RNAi plants, which contains two sperm cells and one vegetative cell.