1. Linking root traits to copper exclusion mechanisms in Silene paradoxa L. (Caryophyllaceae)Ilaria Colzi, Sara Pignattelli, Elisabetta Giorni, Alessio Papini, Cristina Gonnelli, 2015, original scientific article Abstract: Copper is one of the most important pollutants in mine- contaminated soils. This study tests the response in a sensitive population vs a tolerant one of the model species Silene paradoxa in order to understand the general mechanisms of tolerance at the micromorphological and ultrastructural level.
Two populations of Silene paradoxa were grown in hydroponics and exposed to different CuSO4 treatments. The roots were investigated with light, fluorescence and transmission electron microscope. Callose and lignin were spectrophotometrically determined.
The tolerant population constitutively possessed a higher amount of mucilage and was able to reduce the length of the zone between the apex and the first lignified tracheids. Callose production decreased. It did not show remarkable copper-induced ultrastructural modifications, apart from the presence of precipitates in the tangential walls. The sensitive population showed huge nucleoli with a spongy periphery in the central cylinder together with the presence of electrondense granules in the mitochondria. Plastids were rarely observed and generally very electrondense and elongated.
In the copper tolerant population of S. paradoxa some of the root traits concurring to generate metal-excluding roots were suggested to be mucilage and lignin production and the reduction of the subapical root zone.
Keywords: Root, Copper exclusion, Lignin, Callose, Tolerance to copper, Silene paradoxa
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2. The multi-purpose role of hairiness in the lichens of coastal environments: Insights from Seirophora villosa (Ach.) FrödénElisabetta Bianchi, Renato Benesperi, Ilaria Colzi, Andrea Coppi, Lorenzo Lazzaro, Luca Paoli, Alessio Papini, Sara Pignattelli, Corrado Tani, Pamela Vignolini, Cristina Gonnelli, 2019, original scientific article Abstract: The fruticose epiphytic lichen Seirophora villosa, strictly associated with Juniperus shrublands in the
Mediterranean basin, was used to investigate the role of hairiness on a lichen thallus, as a characteristic morphological
trait. We evaluated the effect of hair removal on the physiological parameters of a set of samples,
during desiccation and on exposure to different salt concentrations. Hairy thalli were less affected by salt,
suggesting that during dehydration, the presence of hair protects the thallus from light irradiance, oxidative
stresses and the lipid peroxidation generated by free radicals, and could offer passive, but selective, water
control. Our results showed that hair could not only increase thallus surface and promote water absorption when
availability is low, but could also repel the salt dissolved in water by activating a passive resistance mechanism,
by preventing salt entering.
Keywords: Antioxidant activity
Chlorophyll a fluorescence
Juniperus shrublands
Hair
MDA
Salt stress
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