1-Aminocyclopropane-1-Carboxylate Oxidase Activity Limits Ethylene Biosynthesis in Rumex palustrisduring Submergence

Abstract

Submergence strongly stimulates petiole elongation in Rumex palustris, and ethylene accumulation initiates and maintains this response in submerged tissues. cDNAs from R. palustris corresponding to a 1-aminocyclopropane-1-carboxylate (ACC) oxidase gene (RP-ACO1) were isolated from elongating petioles and used to study the expression of the corresponding gene. An increase in RP-ACO1 messenger was observed in the petioles and lamina of elongating leaves 2 h after the start of submergence. ACC oxidase enzyme activity was measured in homogenates of R. palustris shoots, and a relevant increase was observed within 12 h under water with a maximum after 24 h. We have shown previously that the ethylene production rate of submerged shoots does not increase significantly , suggesting that under these conditions ACC oxidase activity is inhibited in vivo. We found evidence that this inhibition is caused by a reduction of oxygen levels. We hypothesize that an increased ACC oxidase enzyme concentration counterbalances the reduced enzyme activity caused by low oxygen concentration during submergence, thus sustaining ethylene production under these conditions. Therefore, ethylene biosynthesis seems to be limited at the level of ACC oxidase activity rather than by ACC synthase in R. palustris during submergence.

A Comparative Molecular-Physiological Study of Submergence Response in Lowland and Deepwater Rice

“…Ethylene measurements, when submergence treatment terminated, strongly correlated with submergence tolerance in rice and in Rumex sp. (Khan et al, 1987;Vriezen, 2000). The current study indicates that in rice, the duration of submergence also enhances the subsequent ethylene release, suggesting a higher production during the submergence phase.…”

Two Rumex Species from Contrasting Hydrological Niches Regulate Flooding Tolerance through Distinct Mechanisms

“…As expected, this transcriptome-wide analysis showed that aminocyclopropanecarboxylate oxidase, a proxy for enhanced ethylene levels (Vriezen et al, 1999), accumulated in both species. A strong induction of an EIN3 BINDING F-BOX (EBF) OMCL family was observed in R. palustris only.…”

The role of PnACO1 in light- and IAA-regulated flower inhibition in Pharbitis nil

“…(PnACO1) and determined its sequence. The PnACO1 gene encodes for a protein whose expected molecular mass (34.82 kDa) is similar to that of ACC oxidases identified in other plant species (Hudgins et al 2006;Hunter et al 1999;Nie et al 2001;Vriezen et al 1999;Zanetti et al 2002). The largest similarity with respect to the PnACO1 amino acid sequence As an internal control, we used a constitutively expressed actin gene (83 %) is shown in ACO1 proteins from N. attenuata, N. glutinosa, S. tuberosum, as well as A. thaliana ACO2-69 % (Fig.…”