MadSci Network: Botany

Re: Where will more catalase be found? in the plumules or radicles of a bean

Date: Mon Oct 30 19:32:31 2000
Posted By: Maggie Guo, Grad student, Plant Physiologu and Molecular Biology Program, Dept.of Plant Biology, UIUC
Area of science: Botany
ID: 971015308.Bt

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 


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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