Abstract
In higher plants, peroxisomes are known to differentiate into several classes. Glyoxysomes that are abundant in cotyledonary cells, contain enzymes of β-oxidation and glyoxylate cycle to degrade storage lipids for postgerminative growth of oil-seed plants. Peroxisomal malate dehydrogenase(PMDH), that is an enzyme of glyoxylate cycle, has two isoforms, At2g22780(PMDH1) and At5g09660(PMDH2). RT-PCR analysis showed that transcription of PMDH1 was activated during germination and that of PMDH2 was induced in response to light. These data suggest that PMDH1 and PMDH2 play different roles, respectively. Therefore, we investigated Arabidopsis pmdh mutants to elucidate physiological functions of PMDH isoforms.
The pmdh1 and pmdh2 display no phenotypic abnormalities during germination. However, pmdh1pmdh2 requires sucrose for postgerminative growth and defects β-oxidation as well as ped1. These results suggest that PMDHs participate not only in glyoxylate cycle but also in β-oxidation.
