RESUMEN
Marchantia polymorpha L. responds to environmental changes using a myriad set of physiological responses, some unique to the lineage related to the lack of a vascular- and root-system. This study investigates the physiological response of M. polymorpha to high doses of anthracene analysing the antioxidant enzymes and their relationship with the photosynthetic processes, as well as their transcriptomic response. We found an anthracene dose-dependent response reducing plant biomass and associated to an alteration of the ultrastructure of a 23.6% of chloroplasts. Despite a reduction in total thallus-chlorophyll of 31.6% of Chl a and 38.4% of Chl b, this was not accompanied by a significant change in the net photosynthesis rate and maximum quantum efficiency (Fv/Fm). However, we found an increase in the activity of main ROS-detoxifying enzymes of 34.09% of peroxidase and 692% of ascorbate peroxidase, supported at transcriptional level with the upregulation of ROS-related detoxifying responses. Finally, we found that M. polymorpha tolerated anthracene-stress under the lowest concentration used and can suffer physiological alterations under higher concentrations tested related to the accumulation of anthracene within plant tissues. Our results show that M. polymorpha under PAH stress condition activated two complementary physiological responses including the activation of antioxidant mechanisms and the accumulation of the pollutant within plant tissues to mitigate the damage to the photosynthetic apparatus.
RESUMEN
Invasive species success may depend on ecophysiological attributes present in their native area or derived from changes that took place in the invaded environment. We studied the growth and photosynthetic capacity of Berberis darwinii shrubs growing under different light conditions (gap, forest edge and below the canopy) in their native area of Patagonia, Argentina. Leaf photosynthesis results determined in the native area were discussed in relation to information provided by studies carried out under the same light conditions in an invaded area in New Zealand. Shoot elongation, leaf production, stem and leaf biomass per shoot and specific leaf area (SLA, cm2 g-1) were determined in five adult plants, randomly selected in each of three light conditions in two forest sites. Net photosynthesis as a function of PPFD (Photosynthetic Photon Flux Density), stomatal conductance (gs), maximum light-saturated photosynthesis rate (Pmax), Pmass (on mass bases) and water-use efficiency (WUEi) were determined in plants of one site. We predicted that functional traits would differ between populations of native and invasive ranges. In their native area, plants growing under the canopy produced the longest shoots and had the lowest values for shoot emergence and foliar biomass per shoot, while their SLA was higher than gap and forest edge plants. Leaf number and stem biomass per shoot were independent of light differences. Leaves of gap plants showed higher Pmax, Pmass and gs but lower WUEi than plants growing at the forest edge. In its native range B. darwinii grows under different light conditions by adjusting shoot and leaf morphology and physiology. Plants of B. darwinii growing under the same light conditions show similar physiology in native and invasive ranges. This means that for B. darwinii, intra-specific variation of the functional traits studied here do not condition successful spread in new areas.