Figure 2.

DNA Fragmentation in Florets of the Fertile and Sterile Sunflower Lines.

Three stages of anther development in the fertile line and the corresponding stages of development in the sterile line were compared with respect to nuclear DNA fragmentation using the TUNEL assay (bright green to yellow is positive stain).

(A) Fertile line, premeiosis.

(B) Sterile line, premeiosis.

(C) Fertile line, pachytene.

(D) Sterile line, pachytene.

(E) As a negative control, the terminal deoxynucleotidyl transferase enzyme was omitted from the labeling mixture. Sterile line, pachytene.

(F) Fertile line, tetrad stage.

(G) Sterile line, tetrad stage.

m, meiocyte(s); ms, microspores; st, stomium cells; t, tapetal cell(s). Bars = 20 μm.