GLYCOLYTIC GENE-EXPRESSION IN AMPHIBIOUS ACORUS-CALAMUS L UNDER NATURAL CONDITIONS

Acorus calamus L is an amphibious plant, which is exposed to periods o f flooding and consequently hypoxic conditions as a part of its natura l life cycle. Previous experiments under laboratory conditions have sh own that the plant can survive for two months in the complete absence of oxygen, and that during this period the expression of genes encodin g the glycolytic enzymes fructose-1,6-bisphosphate aldolase (ALD), pyr uvate decarboxylase (PDC) and alcohol dehydrogenase (ADH) is induced i n leaves and rhizomes (Bucher and Kuhlemeier, 1993). Here we studied t he expression of ALD and ADH through two years in the natural habitat of A, calamus. Under natural conditions roots and rhizomes were always submerged but newly grown leaves emerged in spring; in autumn the lea ves senesced and the whole plant was submerged again. High Aid and Adh mRNA levels in leaf and rhizome were found only in winter when the le aves were entirely submerged. Upon leaf emergence in spring the mRNA l evels rapidly declined. Under controlled experimental conditions expre ssion of Aid and Adh was not induced by low temperature. The combinati on of laboratory and field experiments supports the hypothesis that ox ygen deprivation rather than low temperature is a major regulator of g lycolytic gene expression in A. calamus. The possible role of other en vironmental factors is also discussed.