CATALASE IS ENCODED BY A MULTIGENE FAMILY IN ARABIDOPSIS-THALIANA (L)HEYNH

The catalase multigene family in Arabidopsis includes three genes enco ding individual subunits that associate to form at least six isozymes that are readily resolved by nondenaturing gel electrophoresis. CATI a nd CAT3 map to chromosome 1, and CAT2 maps to chromosome 4. The nucleo tide sequences of the three coding regions are 70 to 72% identical. Th e amino acid sequences of the three catalase subunits are 75 to 84% id entical and 87 to 94% similar, considering conservative substitutions, Both the individual isozymes and the individual subunit mRNAs show di stinct patterns of spatial (organ-specific) expression. Six isozymes a re detected in flowers and leaves and two are seen in roots. Similarly , mRNA abundance of the three genes varies among organs. All three mRN As are highly expressed in bolts, and CAT2 and CAT3 are highly express ed in leaves.