The role of oxygen in submergence‐induced petiole elongation in Rumex palustris: in situ measurements of oxygen in petioles of intact plants using micro‐electrodes

Abstract

In a study on the mechanism of stimulated petiole elongation in submerged plants, oxygen concentrations in petioles of the flood-tolerant plant Rumex palustris were measured with micro-electrodes. Short-term submergence lowered petiole partial oxygen pressure to c. 19 kPa whereas prolonged submergence under continuous illumination depressed oxygen levels to c. 8-12 kPa after 24 h. Oxygen levels in petioles depended on the presence of the lamina, even in submerged conditions, and on available light. In darkness, petiole oxygen levels in submerged plants dropped quickly to values as low as 0.5-4 kPa. It is hypothesized that prolonged submergence in the light is accompanied by a decrease in carbon dioxide in the petiole. Submergence-enhanced petiolar elongation rate was compared with emergent plants. Peak daily elongation rates occurred at the end of the dark period in emergent plants, but in the middle of the light period in submerged plants. We suggest that this shift in daily elongation pattern is induced by dependence of growth on photosynthetically derived oxygen in submerged plants. Implications of reduced oxygen for ethylene production are raised. Levels of 1-aminocyclopropane-1-carboxylic acid synthase and 1-aminocyclopropane-1-carboxylic acid oxidase and ethylene sensitivity are cited as potential factors in hypoxia-induced ethylene release.

A novel approach to investigate hypoxic microenvironment during rice colonization by Magnaporthe oryzae

“…Here, we measured the oxygen concentration in rice leaves and sheaths using two methods. Methods relying on a Clark‐type microelectrode or microbeads have been widely used to measure the oxygen concentration within a plant tissue (Ober and Sharp, ; Rijnders et al ., ; van Dongen et al ., ; Schmalzlin et al ., ; Mommer and Visser, ; Zabalza et al ., ; Winkel et al ., ). However, these methods require tissue penetration or microinjection into the tissue and do not homogeneously detect in planta oxygen level.…”

Light acclimation, CO2 response and long‐term capacity of underwater photosynthesis in three terrestrial plant species

“…The primary role of light in the survival of submerged plants is most likely the alleviation of submergence‐induced oxygen deficiency by photosynthetically produced oxygen ( Laan et al 1990 ). In petioles of submerged plants of R. palustris darkening immediately induced hypoxic conditions, and illumination restored oxygen levels to values close to atmospheric conditions within minutes ( Rijnders et al 1999 ; see also Gaynard & Armstrong 1987; Stünzi & Kende 1989; Setter et al 1989 ). As far as the present study is concerned, underwater photosynthesis probably maintained normoxic conditions during the light period, although hypoxic conditions may have been present during night‐time.…”

Local adaptation of the clonal plantRanunculus reptansto flooding along a small‐scale gradient

“…We determined the amount of aerenchyma in each of the 18 genotypes in response to flooding because this is the main trait determining internal transport of oxygen and carbon dioxide in flooded plants (Justin & Armstrong 1987; Rijnders et al . 2000).…”

“…We also measured carbohydrate use during 2 weeks of flooding in continuous darkness to determine the ability of each genotype to mobilize and respire stored carbohydrates in the absence of photosynthetically generated oxygen. This is a typical characteristic of flood‐tolerant species (Laan & Blom 1990; Crawford 1992) that may be necessary during nights or in turbid conditions (Rijnders et al . 2000).…”