Characterization of Arabidopsis thaliana transgenic lines expressing high levels of maize NADP-M alic Enzyme

MARIANA SAIGO; ROODRIGO D´ANDREA; VERÓNICA MAURINO; MARÍA F. DRINCOVICH; CARLOS ANDREO

Vienna, Austria

Congreso; XVII International Botanical Congress; 2005

Arabidopsis thaliana (Col-0) was transformed with the maize chloroplastic NADP-malic enzyme (NADP-ME) cDNA under the control of 35SCaMV promoter. This enzyme catalyzes the decarboxylation of malate, generating pyruvate, CO2 and NADPH. The homozygous line with the highest expression level showed a 30-fold increase in NADP-ME activity. Plants grown under normal light intensity showed no major morphological differences compared to the wild type line. However, chlorophyll content as well as photosynthetic performance indicators like CO2 assimilation, Fv/Fm and 􀄭PSII were significantly lower for transgenic lines. These results suggest that the presence of a highly active NADP-ME in chloroplasts of A. thaliana, could have important effects on the reductive power balance of this organelle, diminishing the efficiency of the overall photosynthetic process. The transgenic plants obtained in the present work represent a useful tool to understand the regulation of plastid redox metabolism.