Glutathione-dependent formaldehyde dehydrogenase from golden pothos (Epipremnum aureum) and the production of formaldehyde detoxifying plants

Abstract

Glutathione-dependent formaldehyde dehydrogenase (FALDH) is an enzyme involved in formaldehyde metabolism in eukaryotes. FALDH cDNA was cloned from golden pothos, which is reported to effectively purify gaseous formaldehyde from enclosed room atmosphere. FALDH cDNAs from Arabidopsis, rice and golden pothos were overexpressed in transgenic Arabidopsis, and the enzyme activity was compared to determine the one most suitable for the molecular breeding of formaldehyde-detoxifying plants. The transgenic lines exhibited modified levels of the FALDH transcript, i.e. 10–800% compared to the endogenous transcript, due to either an overexpression or a cosuppression phenotype. The enzyme activity in the crude leaf extract was not proportionate, but did correlate with the transcription levels with certain exceptions. The FALDHs from the three plant species indicated similar enzymatic activity on average. The capacity to detoxify exogenous formaldehyde in the transformants with the FALDHs was determined at the whole plant level. Plants overexpressing FALDH from the three plant species displayed up to a 40% increase in their efficiency to take up exogenous formaldehyde as compared with the wild-type plants. On the other hand, no difference in the survival rate was observed among the transformants and wild type plants on formaldehyde-containing agar medium. These results show the FALDH from golden pothos to be similarly or more effective for detoxifying formaldehyde in transgenic plants compared with Arabidopsis and rice, and that this cDNA is applicable to the molecular breeding of formaldehyde detoxifying plants.