|MadSci Network: Botany|
In plants, catalase is mainly present in microbody, not lysosomes. There are several types of microbody, they are generally active in seed germination process, but they are formed in different tissues under different physiological conditions. For example, leaf peroxisomes are formed in cotyledons of germinating seeds, and the non-green tissues of seeds, lot of unspecified microbodies can be identified. Similarly, plants also have more than one kind of catalase. Researchers have identified at least three different catalase subunits and at least two genes of catalse from castor bean. In the study on the location of these catalase genes, researchers found that one of them mainly expressed(i.e. this kind of catalse appeared) in cotyledons, while the another one mainly expressed in hypocotyl. Therefore it seems like that the first kind of catalase may be specific for leaf peroxisomes, and the second one may be specific for microbodies in non-green tissues. So normaly, we do not tell difference of catalse contain between cotyledon and hypocotol. It is very normal and reseonable for plant growth. The whole life cycle of higher plant is composed of different stages, and every stage is a highly regulated process, genes are tightly regulated by various. Seed germinaition is a very complex one. Catalase is important for plants because it functions in detoxification of hydrogen peroxide. Since hydrogen peroxide is very normal intermeidate product in active tissues, plant must garentee itself that there is enough catalse at anytime. Producing different catalses in different tissues may be a good idea for this garentee. Reference: Suzuki, Mashaharu. et al, 1995, Plant Cell Physiology, 36(2): 273-279 Cutter, Elizabeth Graham. 1978, Plant anatomy, Addison-Wesley Pub. Co.
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