Age-related changes in oxidative stress markers and abscisic acid levels in a drought-tolerant shrub, Cistus clusii grown under Mediterranean field conditions |
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Authors: | Sergi Munné-Bosch Patricia Lalueza |
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Institution: | (1) Departament de Biologia Vegetal, Facultat de Biologia, Universitat de Barcelona, Avinguda Diagonal 645, 08028 Barcelona, Spain |
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Abstract: | Compared with our knowledge of senescence in annuals and biennials, little is known about age-related changes in perennials.
To get new insights into the mechanisms underlying aging in perennials, we measured oxidative stress markers in leaves and
organelles, together with abscisic acid levels in leaves of 2- and 7-year-old Cistus clusii dunal plants grown under Mediterranean field conditions. Recently emerged leaves, which either appeared during autumn or
spring, were compared to evaluate the effects of environmental constraints on oxidative stress and abscisic acid accumulation
as plants aged. Plant aging led to an enhanced oxidation of α-tocopherol and ascorbate, increased lipid peroxidation and reduced
PSII efficiency in leaves during the more stressful conditions of spring and summer, but not during autumn. Analyses of lipid
peroxidation in organelles isolated from the same leaves revealed that oxidative stress occurred both in chloroplasts and
mitochondria. Although both plant groups showed similar leaf water and nitrogen contents throughout the study, abscisic acid
levels were markedly higher (up to 75%) in 7-year-old plants compared to 2-year-old plants throughout the study. It is concluded
that (a) meristematic tissues of C. clusii maintain the capacity to make new leaves with no symptoms of oxidative stress for several years, unless these leaves are
exposed to environmental constraints, (b) leaves of oldest plants show higher oxidative stress than those of young plants
when exposed to adverse climatic conditions, thus supporting the idea that the oxidative stress associated with aging is due
at least partly to extrinsic factors, (c) at the subcellular level, age-induced oxidative stress occurs both in chloroplasts
and mitochondria, and (d) even in the absence of environmental stress, newly emerged leaves accumulate higher amounts of ABA
as plants age. |
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Keywords: | Abscisic acid Aging Antioxidants Oxidative stress Perennials Senescence |
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