Experimental teaching material to learn germination process of rice seeds. II. Distribution of amylase activity within a germinating seed

Abstract

Seed germination process of cereal plants is one of the topics included in biology curriculum of high school. The rice seed consists of three major parts, embryo, endosperm and aleurone layer. Two teaching materials were developed to support the understanding of the close interaction among these parts in germination and initial seedling growth. (1) Spatial distribution of amylase activity within a seed at the germination and post-germination stages: Using a series of slice piece of a germinating seed, amylase induction within the seed was initiated from proximal region with an embryo, followed by gradual expansion towards distal region during germination and subsequent seedling growth. (2) Detection of amylase activity in three parts separated by fractionation: Amylase activities were detected in isolated embryos and isolated aleurone layers. Amylase induction occurred in embryoless seeds which were treated with gibberellin. These experimental data enabled us to confirm that the amylase produced in embryos plays a role in the germination, whereas the amylase produced in aleurone layers is involved in seedling establishment through the digestion of starch deposited in endosperm.