Oxidant-antioxidant balance and tolerance against oxidative stress in pioneer and non-pioneer tree species from the remaining Atlantic Forest.
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2018
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The extensive land occupation in Southeast Brazil has resulted in climatic disturbances and environmental contamination
by air pollutants, threatening the Atlantic forest remnants that still exist in that region. Based on previous
results, we assumed that pioneer tree species are potentially more tolerant against environmental
oxidative stress than non-pioneer tree species from that Brazilian biome. We also assumed that reactive oxygen
species (ROS) are accumulated in higher proportions in leaves of non-pioneer trees, resulting in changes in the
oxidant-antioxidant balance and inmore severe oxidative damage at the cellular level than in the leaves of pioneer
trees. We tested these hypotheses by establishing the relationship between oxidants (ROS), changes in key
antioxidants (among enzymatic and non-enzymatic compounds) and in a lipid peroxidation derivative in their
leaves, aswell as between ROS accumulation and oscillations in environmental stressors, thus permitting to discuss
comparatively for the first time the oxidant-antioxidant balance and the tolerance capacity of tree species of
the Atlantic Forest in SE Brazil.We confirmed that the non-pioneer tree species accumulated higher amounts of
superoxide and hydrogen peroxide in palisade parenchyma and epidermis, showing a less effective antioxidant
metabolism than the pioneer species. However, the non-pioneer species showed differing capacities to compensate
the oxidative stress in both years of study, which appeared to be associated with the level of ROS accumulation,
which was evidently higher in 2015 than in 2016. We also applied exploratory multivariate statistics,
which revealed that the oscillations in these biochemical leaf responses in both functional groups coincided
with the oscillations in both climatic conditions and air pollutants, seemingly showing that they had acclimated already carried out, including Bussotti (2008) that concluded that
early successional species in Mediterranean forests have a lower tolerance
against oxidative stress than late secondary species and Favaretto
et al. (2011) that classified native tree species of the Atlantic Forest
into two major functional groups based on their tolerance against
solar radiation exposure.
Brandão et al. (2017) assumed that pioneer species from disturbed
remnants of the Atlantic Forest in São Paulo (Brazil) are potentially
more tolerant against oxidative stress than non-pioneer species based
on the levels of antioxidants. However, this hypothesis would be definitely
confirmed only if the lower antioxidative capacity in nonpioneer
trees occurred in parallel with increased levels of ROS in the
leaves, resulting in loss of the oxidant-antioxidant equilibrium, severe
oxidative damage at the cellular level and consequently decreased tolerance
against oxidative stress. The present study brought a new contribution
to this broader issue, permitting to discuss comparatively the
oxidant-antioxidant balance and the tolerance capacity of pioneer and
non-pioneer tree species of Atlantic Forest remnants affected by multiple
environmental stressors in SE Brazil.We achieved this goal by establishing
the relationship between oxidants (ROS), changes in key
antioxidants (among enzymatic and non-enzymatic compounds) and
in a lipid peroxidation derivative in their leaves, as well as between
ROS accumulation and oscillations in environmental stressors.
Descrição
Palavras-chave
Antioxidant defenses, Seasonality, Reactive oxygen species, Functional groups
Citação
ESPOSITO, M. P. et al. Oxidant-antioxidant balance and tolerance against oxidative stress in pioneer and non-pioneer tree species from the remaining Atlantic Forest. Science of the Total environment, v. 625, p. 382-393, 2018. Disponível em: <https://www.sciencedirect.com/science/article/pii/S0048969717336896?via%3Dihub>. Acesso em: 02 abr. 2018.