Germin, an Oxalate Oxidase, Has a Function in Many Aspects of Plant Life

Authors: MAHMUT ÇALIŞKAN

Abstract: Germin, a molecular marker of wheat embryo germination, is a remarkably protease-resistant, apoplastic, homopentameric glycoprotein. Different forms of germin found to be related to various aspects of plant development have been discovered. Germins were determined in cereals, dicotyledonous angiosperms, gymnosperms and in a prosit, all these proteins are together called germin-like proteins due to their DNA sequence homology. Cereal germins have oxalate oxidase activity, an activity which generates hydrogen peroxide by degrading oxalic acid. Both of these molecules have been implied in the regulation of cell development, differentiation, signalling and defence systems of plants. The germin-like proteins found in dicotyledonous plants do not appear to have oxalate oxidase activity. Recently, germin-like proteins were shown to be related to seed storage proteins (vicilins, legumins), SBS (sucrose-binding proteins) and spherulins. On the basis of these similarities, it was proposed that all these proteins are members of a "superfamily" which are structurally related but functionally distinct proteins. Germin and germin-like proteins seem to be involved in the various important processes of plants including development, osmotic regulation, photoperiodic oscillation, defence and apoptosis.

Keywords: Plant development, cell wall, germin, germin-like proteins, oxalate oxidase.

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