Waterlogging and Petiole Epinasty in Tomato: The Role of Ethylene and Low Oxygen

Abstract

SUMMARY Waterlogging the soil promotes epinastic growth of tomato petioles and increases the concentration of ethylene which can be extracted from various parts of the shoot. These concentrations exceed those normally required to promote epinasty when applied to the shoots of non‐waterlogged plants. Waterlogging also results in a rapid decline in the concentration of dissolved oxygen in the soil water. Low concentrations of oxygen around the roots of plants growing in nutrient solution promote epinastic growth and also increase ethylene concentration in the leaves. Experiments with detached shoots indicate that the root system is required for the response to low O2concentrations to develop. Ethylene concentrations in the soil can increase during waterlogging to levels which may allow sufficient movement into the shoot to stimulate epinasty. Treatment with substances which can inhibit the action of ethylene, such as carbon dioxide or 7‐chloro‐4‐ethoxycarbonylmethoxy‐5‐methyl‐2, 1,3‐benzothiadiazole also inhibit the epinastic response in waterlogged plants, in plants with low O2 concentrations around the roots and in plants treated with ethylene. The internal level of carbon dioxide in the lower leaves is little affected by waterlogging for up to 96 h.

Enhanced chickpea growth-promotion ability of a Mesorhizobium strain expressing an exogenous ACC deaminase gene

“…The high production and accumulation of ethylene in shoots results from the high ACC levels, synthesized in roots by ACC synthase, then transported from the root system to shoot where it is converted to ethylene by ACC oxidase (Bradford et al 1982). Since oxygen concentrations of waterlogged root systems are too low or nonexistent, the conversion of ACC to ethylene by ACC oxidase cannot take place (Jackson and Campbell 1976;Bradford and Dilley 1978;Wang and Arteca 1992;Banga et al 1997).…”

Effects of Low O2 Root Stress on Ethylene Biosynthesis in Tomato Plants (Lycopersicon esculentum Mill cv Heinz 1350)

“…Waterlogging been reported to cause elevated ethylene levels and epinasty in the shoot regardless of whether the condition is imposed by waterlogging or by flushing with N2 (4,12,14). It has been shown that ethylene production by maize (Zea mays L.) roots exposed to 5 kPa oxygen was inhibited by AVG supplemented to the nutrient solution and this also reduced aerenchyma formation (13).…”

“…Under aeration, AOA stimulated ACC synthase activity in both the roots and leaves. However, in combination with low 02 conditions, AOA caused a stimulation in ACC synthase activity in the leaves and no effect in the roots.Ethylene production is observed in all higher plants, where it is involved in numerous aspects of plant growth and development but most notably as a response to stress conditions (1).Waterlogging been reported to cause elevated ethylene levels and epinasty in the shoot regardless of whether the condition is imposed by waterlogging or by flushing with N2 (4,12,14). It has been shown that ethylene production by maize (Zea mays L.) roots exposed to 5 kPa oxygen was inhibited by AVG supplemented to the nutrient solution and this also reduced aerenchyma formation (13).…”

“…Epinastic growth oftomato petioles has been shown to occur within 12 h following flooding ofthe soil (12). Exposure to ethylene will also cause petiole epinasty in a variety of plants (9).…”

Leaf Epinasty in Chrysanthemum: Enabling Breeding Against an Adverse Trait by Physiological Research

“…Ethylene is a second phytohormone that might be involved in leaf epinasty, for the main reason that it can cause differential growth, in terms of petiole epinasty (Jackson and Campbell, 1976;Reid et al, 1981;El-Iklil et al, 2000) or an exaggerated apical hook (Guzman and Ecker, 1990;Stepanova and Alonso, 2005). Other than affecting the sinksource balance, disbudding might enhance ethylene production, since plants are wounded which may cause an increase in ethylene production (Druege, 2006).…”