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Melatonin systemically ameliorates drought stress‐induced damage in M edicago sativa plants by modulating nitro‐oxidative homeostasis and proline metabolism
Author(s) -
Antoniou Chrystalla,
Chatzimichail Giannis,
Xenofontos Rafaella,
Pavlou Jan J.,
Panagiotou Evangelia,
Christou Anastasis,
Fotopoulos Vasileios
Publication year - 2017
Publication title -
journal of pineal research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.881
H-Index - 131
eISSN - 1600-079X
pISSN - 0742-3098
DOI - 10.1111/jpi.12401
Subject(s) - melatonin , oxidative stress , homeostasis , apx , lipid peroxidation , biology , reactive oxygen species , antioxidant , biochemistry , proline , catalase , endocrinology , amino acid
Recent reports have uncovered the multifunctional role of melatonin in plant physiological responses under optimal and suboptimal environmental conditions. In this study, we explored whether melatonin pretreatment could provoke priming effects in alfalfa ( Medicago sativa L.) plants subsequently exposed to prolonged drought stress (7 days), by withholding watering. Results revealed that the rhizospheric application of melatonin (10 μmol L −1 ) remarkably enhanced the drought tolerance of alfalfa plants, as evidenced by the observed plant tolerant phenotype, as well as by the higher levels of chlorophyll fluorescence and stomatal conductance, compared with nontreated drought‐stressed plants. In addition, lower levels of lipid peroxidation ( MDA content) as well as of both H 2 O 2 and NO contents in primed compared with nonprimed stressed plants suggest that melatonin pretreatment resulted in the systemic mitigation of drought‐induced nitro‐oxidative stress. Nitro‐oxidative homeostasis was achieved by melatonin through the regulation of reactive oxygen ( SOD , GR , CAT , APX ) and nitrogen species ( NR , NADHde) metabolic enzymes at the enzymatic and/or transcript level. Moreover, melatonin pretreatment resulted in the limitation of cellular redox disruption through the regulation of the mRNA levels of antioxidant and redox‐related components ( ADH , AOX , GST 7, GST 17 ), as well via osmoprotection through the regulation of proline homeostasis, at both the enzymatic (P5 CS ) and gene expression level ( P5 CS , P5 CR ). Overall, novel results highlight the importance of melatonin as a promising priming agent for the enhancement of plant tolerance to drought conditions through the regulation of nitro‐oxidative and osmoprotective homeostasis.