Physiological Characteristics of Expanding and Expanded Leaves of Vitis vinifera L. cv. Assyrtiko in Climate Change Conditions

The impact of climatic change on viticulture is expected to be severe in the Mediterranean area in the future. The scope of this study is the evaluation of the leaf functional and optical properties of grapevine (Vitis vinifera L.) cultivar (cv.) Assyrtiko and its response to abiotic stress conditions (elevated temperature and water deficiency) caused by climatic change. Plants of grapevine cv. Assyrtiko were placed in a growth chamber in the Botany Department of the National and Kapodistrian University of Athens, Greece and four indoor environmental treatments were applied, concerning temperature (ambient versus ambient +2 °C) and water availability (well-watered versus water stressed). The photosynthetic pigments (chlorophylls a and b and carotenoids) were determined as well as the leaf area, dry weight and specific leaf area in expanding and fully expanded leaves of the treated plants. Using a UV/VIS spectrophotometer (Perkin Elmer Lambda-950), equipped with an integrating sphere, the reflectance (R) and the transmittance (T), were measured in situ, between 250 and 2500 nm wavelength, in both adaxial and abaxial leaf surfaces of the grapevine cv. Assyrtiko and the absorbance (A) was calculated. It is likely that leaf chlorophyll content declined under drought and elevated temperature conditions

From Biodiversity to Musketry: Detection of Plant Diversity in Pre-Industrial Peloponnese during the <i>Flora Graeca</i> Expedition

As the interest in natural, sustainable ecosystems arises in many fields, wild plant diversity is reconsidered. The present study is based on extant literature evidence from the journey of John Sibthorp (Professor of Botany, Oxford University) to Peloponnese (Greece) in pre-industrial time. In the year 1795, Peloponnese was a botanically unknown region, very dangerous for travellers and under civil unrest, in conjuncture with a pre-rebellion period. Our study reveals approximately 200 wild plant taxa that were collected from Peloponnese localities in 1795, transported to Oxford University (UK), and quoted in the magnificent edition Flora Graeca Sibthorpiana of the 19th century. Moreover, these plants currently constitute a living collection in Peloponnese, confirmed according to updated data on the vascular Flora of Greece. The presented lists constitute a source of information for plant biologists, linking the past to the present, shedding light on the study of adaptive traits of wild Mediterranean plants and revealing the temporal dimension of natural history. Nowadays, increasing and thorough understanding of the considered plants’ functionality to abiotic and biotic environmental stimuli provides a new framework of sustainability and management options

Acclimation of the Grapevine <i>Vitis vinifera</i> L. cv. Assyrtiko to Water Deficit: Coordination of Structural and Functional Leaf Traits and the Dynamic of Calcium Oxalate Crystals

Grapevine leaves contain abundant CaOx crystals located either within the mesophyll in the form of raphides, or in the bundle sheaths as druses. CaOx crystals function as internal carbon pools providing CO2 for a baseline level of photosynthesis, named “alarm photosynthesis”, despite closed stomata; thus, preventing the photoinhibition and the oxidative risk due to carbon starvation under adverse conditions. Structural and functional leaf traits of acclimated grapevine plants (Vitis vinifera L. cv. Assyrtiko) were investigated in response to water availability, in order to evaluate the dynamic functionality of CaOx. Leaf water potential, leaf area, leaf mass per area, stomatal properties, gas exchange parameters and performance index (PI) were decreased in leaves of vines acclimated to water deficit in comparison to the leaves of well-irrigated vines, although the chlorophyll fluorescence parameters showed that the operational efficiency of the photosystem II (PSII) photochemistry (Fv/Fm) did not change, indicating that the photosynthetic apparatus was not subjected to water stress. During the afternoon, more than half of the morning’s existing druses disappeared in the drought-acclimated leaves. Also, the raphides’ area of the drought-acclimated leaves was reduced more than that of the well-watered leaves. The substantial decomposition of druses under water deficit conditions compared to that of the raphides may have important implications for the maintenance of their different though overlapping roles. According to the results, it seems likely that, under water deficit conditions, a mechanism of “alarm photosynthesis” provides an additional tolerance trait in the leaves of Vitis vinifera cv. Assyrtiko; hence, leaf structure relates to function