LONG-TERM ANOXIA TOLERANCE - MULTILEVEL REGULATION OF GENE-EXPRESSIONIN THE AMPHIBIOUS PLANT ACORUS-CALAMUS L

Acorus calamus is a monocotyledonous wetland plant that can withstand extremely long periods of anoxia. We have investigated the expression of genes coding for pyruvate decarboxylase (Pdc), alcohol dehydrogenas e (Adh), and fructose-1,6-bisphosphate aldolase (Ald) during periods o f anoxia ranging from 2 h to 2 months. Upon anoxic incubation, Pdc mRN A levels peak at 6 h, followed by Adh and Ald, which peak at 12 and 72 h, respectively. Subsequently, the mRNA levels of all three genes dec line within days to low levels. In contrast, alcohol dehydrogenase (AD H) protein levels increase steadily for at least a week and then remai n constant. Native gel electrophoresis demonstrates the presence of tw o sets of ADH isozymes, one present constitutively, the other enhanced during anoxia. Translation initiation factor 4A protein levels, used as a control, remain constant during 2 months of anoxia. The results s uggest that A. calamus has developed a complex anaerobic response cons isting of differential regulation of transcription, translation, and p osttranslational processes.