Abstract
In germinating fatty seedlings, microbodies are functionally transformed to leaf peroxisomes from glyoxysomes during greening, and then converted to glyoxysomes from leaf peroxisomes during senescence. Immunocytochemical studies revealed that glyoxysomes can exchange directly into leaf peroxisomes during greening and leaf peroxisomes are once again directly converted to glyoxysomes during senescence. The reversible transformations of microbodies are regulated at various levels, such as gene expression, splicing of the mRNA and degradation of microbody proteins. The regulatory mechanisms underlying this organelle differentiation are described.