The Stem Vasculature of Na1/Na1 and Na2/Na2 Mutants in Maize

Abstract The vasculature of two recessive dwarf mutants, nana-1 (nal) (FIG 1) and nana-2 (na2) (FIG 2) of maize (Zea mays)were studied. All the plants used in this study were grown at the field station of University of Western Ontario, London, Ontario, Canada, in the summer of 2000. The specimens were fixed in methanol, serially sectioned with a razor blade using a specially made jig. The image was obtained by using a modified Acer 620T flat-bed scanner in liquid (Cheng et al., 2001). The optical sections were obtained by twophoton florescence microscopy using an Olympus Fluorview FL300 confocal microscope equipped with a Spectra-Physics Mai-Tai tunable ultra-fast Ti-sapphire laser. Excitation wavelengths was set at 780nm NIR with a pulse width of l00fs, <550nm autofluorescence was detected. Extended focus views were generated by using AutoQuant's AutoVisualize-3D™ software. Different from the parallel arranged longitudinal vascular bundles commonly found in the internodes of wild type, nal/nalhas a complex stem vasculature (FIG 3)(Cheng et al., 2000a; 2000b).