Rescue of fertility in the myb26 mutant by expression of MYB26 regulated by the NST2 promoter. A, NST2pro:GUS expression in wild type, showing expression in extending filaments prior to dehiscence, and in postmeiotic anthers. B, NST2pro:GUS expression in the myb26 mutant, showing expression in extending filaments prior to dehiscence, and in postmeiotic anthers. C to K, Stamen stained for secondary thickening with acridine orange/ethidium bromide and visualized by confocal microscopy; (C, F, and I) wild-type anthers and filaments; (D, G, and J) NST2pro:MYB26 expression in the myb26 mutant showing high levels of secondary thickening in the endothecium and increased secondary thickening in the filament; (E, H, and K) myb26 mutant with no thickening in the anther endothecium. Scale bars represent 200 µm in C, 150 µm in D, 300 µm in E, 75 µm in F to H, and 150 µm in I to K.