Effect of drought and rewatering on the antioxidant response of Medicago truncatula plants
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Journal
Plant Signaling and Behavior
Date Issued
February 2011
Abstract
Effects of water stress on plants have been well-documented in several reports [1].
However, the combined responses to drought and rewatering and its underlying
mechanism are relatively unknown. The present study attempts to describe alterations in
the physiology and cellular status of Medicago truncatula tissues that result from and
subsequently follow a period of moderate water deficit. Physiological processes and
cellular damage levels were monitored in roots and leaves by means of
spectrophotometric determination of lipid peroxidation, chlorophyll loss and H202
content, further supported by stomatal conductance measurements in leaves. During water
stress, cells in both organs displayed increased damage levels and reactive oxygen species
content, while leaves showed reduced stomatal conductance. Upon rewatering, plants
recovered displaying readings similar to pre-stress control conditions. Furthermore,
molecular analysis of antioxidant gene expression by quantitative real-time PCR revealed
differential regulation in a number of genes examined. Overall, M truncatula plants
demonstrated increased sensitivity to drought-induced oxidative damage; however, this
was reversed following rewatering indicating a great elasticity in the plant's capacity to
cope with free oxygen radicals. Understanding how plants response to episodic drought
and watering pulse and the underlying mechanism could prove to be remarkably helpful
towards the implementation of vegetation management practices in climatic changing.
However, the combined responses to drought and rewatering and its underlying
mechanism are relatively unknown. The present study attempts to describe alterations in
the physiology and cellular status of Medicago truncatula tissues that result from and
subsequently follow a period of moderate water deficit. Physiological processes and
cellular damage levels were monitored in roots and leaves by means of
spectrophotometric determination of lipid peroxidation, chlorophyll loss and H202
content, further supported by stomatal conductance measurements in leaves. During water
stress, cells in both organs displayed increased damage levels and reactive oxygen species
content, while leaves showed reduced stomatal conductance. Upon rewatering, plants
recovered displaying readings similar to pre-stress control conditions. Furthermore,
molecular analysis of antioxidant gene expression by quantitative real-time PCR revealed
differential regulation in a number of genes examined. Overall, M truncatula plants
demonstrated increased sensitivity to drought-induced oxidative damage; however, this
was reversed following rewatering indicating a great elasticity in the plant's capacity to
cope with free oxygen radicals. Understanding how plants response to episodic drought
and watering pulse and the underlying mechanism could prove to be remarkably helpful
towards the implementation of vegetation management practices in climatic changing.
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