Abstract Eleocharis carniolica W.D.J. Koch (Cyperaceae) is an endangered wetland spike rush mainly threatened by habitat loss and fragmentation. Understanding the germination ecology of this species is essential to perform successful conservation and restoration actions. In this study, we investigated the effect of vernalization (i.e. cold stratification), gibberellic acid (GA3) and chemical scarification on seed germination of E. carniolica from wild populations in northern Italy. The results showed that vernalization (i.e. 8-weeks at 4°C) significantly improved germination probability, speed, and uniformity compared to non-stratified seeds. Gibberellic acid treatment alone or in combination with vernalization did not show a significant improvement in germination. Chemical scarification using sodium hypochlorite increased germination probability, with 8 hours of scarification showing the highest success rate. However, 24-hour scarification had a negative impact on germination. Overall, vernalization was found to be the most effective method to enhance germination in E. carniolica . These findings provide valuable insights into the seed germination ecology of this endangered species, aiding in its exsitu conservation, propagation, and in-situ restoration efforts. Moreover, they have important implications on future germination dynamics of this endangered species, especially with predicted climate change scenarios.
Abstract Some plant species are capable of significant reduction of xylem embolism during recovery from drought despite stem water potential remains negative. However, the functional biology underlying this process is elusive. We subjected poplar trees to drought stress followed by a period of recovery. Water potential, hydraulic conductivity, gas exchange, xylem sap pH, and carbohydrate content in sap and woody stems were monitored in combination with an analysis of carbohydrate metabolism, enzyme activity, and expression of genes involved in sugar metabolic and transport pathways. Drought resulted in an alteration of differential partitioning between starch and soluble sugars. Upon stress, an increase in the starch degradation rate and the overexpression of sugar symporter genes promoted the efflux of disaccharides (mostly maltose and sucrose) to the apoplast. In turn, the efflux activity of the sugar‐proton cotransporters caused a drop in xylem pH. The newly acidic environment induced the activity of apoplastic invertases leading to the accumulation of monosaccharides in the apoplast, thus providing the main osmoticum necessary for recovery. During drought and recovery, a complex network of coordinated molecular and biochemical signals was activated at the interface between xylem and parenchyma cells that appeared to prime the xylem for hydraulic recovery.
Seagrass meadows play a vital role for lagoon ecosystems and their biota, sustaining multiple ecosystem services. Their distribution and functioning are closely tied to the environmental pressures induced by global changes. Long-term monitoring of seagrass species and communities is, hence, important to depict their response to past and future scenarios. The availability of long term open-access satellite data offers a new remote sensing perspective for monitoring seagrass communities dynamics in shallow waters, especially when combined with machine learning algorithms. In this study, seasonal multispectral images (from 1999 to 2019) were collected from Landsat 5 Thematic Mapper and 8 Operational Land Imager satellites to map the seagrass meadows, at the community and species levels, within the vast Grado and Marano lagoon (Northeast Italy) using a Random Forest (RF) algorithm. RF models were calculated using an extensive field training dataset collected in 2010 (n = 426) and reached an overall accuracy of 0.92 and 0.76 for the classification at the community and species levels, respectively. The change detection analysis revealed an increase of 14.16 km2 (+ 39%) of the whole seagrass community cover over the period, at a rate of 1.59 km2year−1. Despite the coarse spatial resolution (30 m) of the Landsat's images, the classification of seagrasses at species level achieved a good overall accuracy (0.76), evidencing Nanozostera noltei as the species with the highest cover increase (+13.87 km2 over the time period). The observed expansion is likely caused by an increase of the sea water influence that is radically modifying Adriatic brackish water bodies, emphasizing the connection between the ongoing environmental changes and the rapid responses of seagrass meadows.
The H + /PP i stoichiometry of the mitochondrial H + ‐PP i ase from pea ( Pisum sativum L.) stem was determined by two kinetic approaches, and compared with the H + /substrate stoichiometries of the mitochondrial H + ‐ATPase, and the vacuolar H + ‐PP i ase and H + ‐ATPase. Using sub‐mitochondrial particles or preparations enriched in vacuolar membranes, the rates of substrate‐dependent H + ‐transport were evaluated: by a mathematical model, describing the time‐course of H + ‐gradient (ΔpH) formation; or by determining the rate of H + ‐leakage following H + ‐pumping inhibition by EDTA at the steady‐state ΔpH. When the H + ‐transport rates were divided by those of PP i or ATP hydrolysis, measured under identical conditions, apparent stoichiometries of ca 2 were determined for the mitochondrial H + ‐PP i ase and H + ‐ATPase, and for the vacuolar H + ‐ATPase. The stoichiometry of the vacuolar H + ‐PP i ase was found to be ca 1. From these results, it is suggested that the mitochondrial H + ‐PP i ase may, in theory, function as a primary H + ‐pump poised towards synthesis of PP i and, therefore, acting in parallel with the main H + ‐ATPase.
The name Thymus dalmaticus var. carstiensis, basionym of Th. carstiensis, is here lectotypified. This taxon is currently regarded as the hybrid between Th. longicaulis and Th. pulegioides or as a synonym of Th. serpyllum. A morphological comparison among Th. dalmaticus var. carstiensis and its putative parental species are performed. A detailed morphological description and information about habitat, phenology, distribution and taxonomy are provided. Furthermore, Th. carstiensis is here recorded for the first time from Slovenia.
