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Agronomy Day 2008

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Tour B

Ethylene – How Plants Talk about Stress

Fred E. Below
Fred E. Below
Crop Physiology
Department of Crop Sciences
Martin Uribelarrea
Martin Uribelarrea
Research Associate
Department of Crop Sciences

Crops are continually subject to environmental and biological stresses that chip away at their yield potential. Many of the physiological and plant growth responses to these stresses are modulated by the natural plant hormone ethylene. The biosynthesis of ethylene is enhanced under stress, which may result in measurable yield losses. Ethylene is unique among plant growth regulators in that it is a gas, which allows it to be released by stressed plants, and perceived by adjacent plants. Increases in ethylene level can mimic many of the symptoms of plant stress, or can induce acclimation processes with aid in plant tolerance and survival to stress. Thus, in a way plants talk to each other about stresses via ethylene.

Ethylene is known to play a role in shade avoidance at high plant populations, in mediating the time course of leaf senescence, and in plant responses to a number of abiotic stresses like high temperature. We are investigating some new and existing technologies as a way of protecting plants from stress, by either altering the level of plant ethylene, or alternatively, by decreasing the plant’s sensitivity to ethylene.

We have found that the competitive ethylene inhibitor 1-MCP, which decreases the plant’s sensitivity to ethylene, minimizes the negative impacts of supra-optimal plant populations, and decreases yield reductions due to high temperature stress. Conversely, increasing the level of plant ethylene with the slow-release ethylene formulation, ethephon enhances the negative effects of high plant population and of high temperature, and makes the plants noticeably shorter (see figure). We have also shown that the late-season ‘greening effect’ associated with strobilurin based fungicides (see figure) is associated with a decrease in ethylene biosynthesis, which acts as a long-term signal to alter the senescence trajectory of the leaves. Tools to manage plant ethylene are clearly one way to mitigate plant stress resulting in higher crop productivity.

EthephonUTC Strobilurin Fungicide

Graphic depiction of agronomic effects associated with ethylene metabolism in corn plants. Stature reduction caused by an application of ethephon (ethylene) during vegetative stages (left), and the late season greening effect caused by a strobilurin fungicide (right), which reduces ethylene synthesis by the plant.

Energizing Agriculture