Williamsville North High School

State University of New York


University of Western Ontario

Abnormal node development in na1/na1 --Cheng, W, Cheng, P-c, Walden, DB The phenotype of na1/na1 is characterized as dwarf plant. The dwarf character is associated with an abnormal development in the stem. Instead of the well-defined nodes and internodes found in the normal wild type stem, na1/na1 develops a stem lacking organized nodal and internodal vasculature. Different from the parallel longitudinal vascular bundles found in the internode of wild type, na1/na1 has a poorly structured arrangement. In addition, the interconnecting vascular bundles are not limited to the nodal region as found in the wild type, but can be found at any level of the stem (arrows).

Figure 1 is a longitudinal section of a na1/na1 stem showing the stem with the aforementioned features. The plant was grown in 1999 summer nursery at the field station of University of Western Ontario, London, Canada. The specimen was fixed in 1:3 acetic acid/ EtOH, stained in diluted Schiff’s reagent (10%), washed in 0.1 M metabisulphate solution (with 1 ml of 1 N HCl per liter), dehydrated in EtOH and cleared in methyl salicylate. Note the vascular bundles extend into the leaves but are not connected to a nodal structure (double-arrows).

Figure 1.

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