Gene expression in plants changes according to changes in the abiotic environment. However, there are few teaching materials on this phenomenon. Plant seedlings are continued to elongate as long as they stay in the dark, and expression of the GA3oxidase gene is also continued in the dark (Ait-Ali et al. 1999). The students must comprehend the phenomenon through the comparison between the gene expression in the dark and that in the light. Detection of the gene expression needs to handle mRNA of the gene. However, the instruments to extract the labile mRNA are not installed in the high schools. Therefore, crude extracts of seedlings of spinach (Spinacia oleracea) were directly processed with the reverse transcription kit, and the cDNA of the SoGA3ox were obtained without the handling of the mRNA. PCR-amplified products of the cDNA are detected electrophoretically.The effectiveness of our practice was assessed with pre- and post-test. After the practice, 93% of the students answered that the elongation of seedlings in the dark caused by the increased gene expression of the SoGA3ox. The students found that the expression of the SoGA3ox and the elongation of the seedlings in the dark were disappeared in the light, and successfully linked the expression of the SoGA3ox to the elongation of the seedlings in the dark. These assessments indicated our teaching materials were effective for the students to comprehend that plants responded the abiotic environment via the alteration of the plant hormonal.
The flower of angiosperm consists of four different types of floral organs; sepals, petals, stamens, and carpels (pistils), which are produced in concentric circles called whorls. The ABC model has explained that combinations of only three classes of homeotic genes define each identity of the four floral organs. This simple model is addressed in all the high school “Advanced Biology” (Seibutsu) textbooks under the Course of Study 2009. The hypothesis of floral organ development was constructed by observations of altered flowers and genetic approach of Arabidopsis mutants. However, the flower structure diagrams of the mutants are not consistent with the photograph of flowers in many authorized textbooks. There would be two reasons for insufficient diagrams; the organ of the fourth whorl is regarded as one pistil in spite of two fused carpels in Arabidopsis flowers, and there is no explanation that Class C gene controls the flower determinate. Therefore, we propose that, for understanding the theory of ABC model, it should be described that angiosperm floral organs, sepals, petals, stamens, and carpels, are initiated as separate whorls and a pistil consists of fused some carpels or a single carpel. And then, the ABC model should be explained as a scientific approach to establish hypothesis based on experimental results.