Teaching materials to show visually meiotic pairing, separation and recombination of chromosomes in a bigeneric hybrid Gasteria lutzii x Aloe aristata were developed by genomic in situ hybridization (GISH) using the DNA of the original species as a probe. Genomic in situ hybridization is a molecular technique which now allows chromosomes from different parents to be “painted” different colors.
Chromosome painting by GISH enabled the direct and clear study of homoeologous chromosome behavior during the meiotic process. That is, it become possible through color-coding to present visually the following: reduction of chromosome numbers by the bivalent formation and random assortment of paired chromosomes and segregation to both poles at first meiotic division, followed by a separation of chromatids of each chromosome to the opposite poles and transmission of them to the gametes at second meiotic division.
Using the pictures provided by GISH, students could understand the mechanism of separation and recombination of chromosomes as different genomes. Then, students could acknowledge that intergenomic recombinations were incorporated into the gametes.
In order to allow students to understand the systematics and evolution of plants, the qualitative analysis of fat-soluble photosynthetic pigments by the procedure of thin-layer chromatography was carried out in a senior high school biology class. The materials used in the class were Oscillatoria sp. (Cyanophyta), dried “Nori” Porphyra sp. (Rhodophyta), Undaria pinnatifida (Phaeophyta), Spirogyra sp. (Chlorophyta), and Conocephalum conicum (Bryophyta). Through practical teaching, the students seemed to understand 1) the similarity and diversity of photosynthetic pigments among plant divisionsin Prokaryota and Eukaryota and 2) the course of plant evolution fromgreenalgae to terrestrial plants.