Histo-anatomical leaf variations related to depth in Posidonia oceanica

2015 ◽  
Vol 42 (4) ◽  
pp. 418 ◽  
Author(s):  
Silvia Nicastro ◽  
Anna M. Innocenti ◽  
Nicodemo G. Passalacqua
Keyword(s):  
Anatomical Variation ◽  
Light Availability ◽  
Posidonia Oceanica ◽  
Absorption Efficiency ◽  
Epidermal Cells ◽  
Vascular Bundles ◽  
Terrestrial Plants ◽  
Mesophyll Cells ◽  
Seagrass Meadows ◽  
Functional Efficiency

The purpose of our study is to explore the acclimation of Neptune seagrass (Posidonia oceanica (L.) Delile) to depth by characterising the histo-anatomical leaf modifications. P. oceanica is the dominant seagrass and main habitat constructor of seagrass meadows in the Mediterranean Sea. Meadows play an important biological and ecological role in marine ecosystems, serving as a habitat for a large diversity of species and an efficient erosion protection system for our coasts. Seagrasses are very sensitive to change in light availability and small changes can have significant effects on growth, abundance and distribution. In this study, we analyse changes in P. oceanica leaves collected at –5 m, –15 m and –25 m depth in the Cirella meadow (Tyrrhenian coast, Southern Italy) in order to determine their depth-related histo-anatomical variation. Two main changes were observed at depth: (1) photosynthetic epidermal cells showed smaller chloroplasts but in the same number; and (2) leaves showed smaller epidermal cells and in greater number. Hence, the photosynthetic surface of P. oceanica leaves remains the same at different depths but pigment absorption efficiency can be significantly enhanced with depth. This response supports the differential photoacclimatory response of seagrasses with respect to terrestrial plants previously documented. Mesophyll cells are smaller with depth and more numerous, with a consequent increase in leaf density. The number of vascular bundles also increases, which allows improved functional efficiency of the transport system and solute exchange. Our study is a new contribution to the morpho-functional implications of the histo-anatomy of P. oceanica.

scholarly journals Posidonia oceanica molecular adaptation to the light environment

2015 ◽  
Author(s):  
Gabriele Procaccini ◽  
Emanuela Dattolo ◽  
Chiara Lauritano ◽  
Miriam Ruocco ◽  
Lazaro Marin-Guirao
Keyword(s):  
Environmental Changes ◽  
Light Availability ◽  
Posidonia Oceanica ◽  
Light Sensitivity ◽  
Light Environment ◽  
Molecular Adaptation ◽  
Important Species ◽  
Light Regimes ◽  
Seagrass Meadows ◽  
The Impact

Seagrass meadows are among the most productive ecosystems, with Posidonia oceanica being the most important species along the Mediterranean coastline. This species forms extensive mono-specific meadows that are extremely sensitive to medium-high levels of disturbance and are being threatened by fast environmental changes caused by global warming and increasing human activities. The impact can either reflect in higher turbidity along the water column and in increased UV radiation, making the light availability one of the most important factors affecting P. oceanica distribution. Plants developed mechanisms of adaptations at multiple levels to track and cope with fluctuations and changes in the light environment. At molecular level, the modulation of gene expression in response to environmental changes allows plants to optimize the utilization of light energy for growth and to prevent damages due to its excess. To detect the relevant molecular adaptation strategies evolved by P. oceanica and to assess the plasticity showed in the acclimation under different light regimes, we are employing studies both in natural and controlled conditions. Here, we describe the differences in photo acclimation of plants living along the bathymetric cline observed in field and in a common garden experiment in mesocosms, after the exposition to contrasting light regimes. Using a transcriptional approach (both RT -qPCR and RNA-seq) coupled with a physiological one, we are also testing potential divergences existing among populations and individuals related to light sensitivity. These data should supply new insights for the management of seagrasses ecosystems, for the development of most successful transplantation strategies and ultimately for conservation of biodiversity of these precious ecosystems.

Studies on Graminicolous Species of Phyllachora Fckl. II.. Invasion of the host and development of the fungus

1963 ◽  
Vol 11 (2) ◽  
pp. 131 ◽  
Author(s):  
DG Parbery
Keyword(s):  
Life Cycle ◽  
Close Contact ◽  
Detailed Examination ◽  
Epidermal Cells ◽  
Vascular Bundles ◽  
Mesophyll Cells ◽  
Full Life Cycle ◽  
Full Life ◽  
Made In ◽  
Mechanical Tissue

Infection of grasses by species of Phyllachora Fckl. has been observed, and a detailed examination of the life cycle of two species of this genus has been made on hosts artificially inoculated while growing under glass-house conditions. Gemiiiatiiig ascospores of P. ischaemi and P. parilis prodced appressoria on the leaves of their respective hosts, Ischaemum australe and Paspalurn orbiculare. From each appressorium an infection peg penetrated into the lumen of an epidermal cell and expanded into a normal hypha. Some branches of this hypha invaded adjacent epidermal cells, thus laying the foundations of the clypeus, while other branches invaded the underlying mesophyll cells. At first all hyphae were intracellular and passed from cell to cell by means of fine infection hyphae produced by appressorium-like swellings of the hyphae appressed to the cell wall. Intercellular mycelium was found at a later stage when hyphae were forming perithecium initials. The observation that the clypeus developed independently of the perithecium dispels some existing confusion about its origin. The clypeus developed in the epidermal cells of the host and not as an outgrowth of the ostiolar region of the perithecium. The perithecium initial developed deep in the mesophyll, and in the case of Phyllachora parilis was preceded by the formation of a subclypeal pycnidium containing filiform spores. In each case, the perithecium expanded until its ostiolar region came into close contact with the clypeus. The ostiole then developed right through the ciypeus, and its development is believed to be lysigenous. The mouth of the ostiole remained closed by a membrane which appeared to be the undissolved cuticle. It was noted that asci of all species examined possessed an ascus crown, a structure not previously observed in species of this genus. It has been found that the anatomy of the host can determine the form of some structures of Phyllachora spp. Clypeus thickness is governed by the size of the epidermal cells, while its radial expansion is checked by the mechanical tissue associated with vascular bundles. Similarly, perithecium size and shape are influenced by the amount of mechanical tissue in a leaf. The time for P. ischaemi to complete its life cycle was influenced by seasonal conditions. Colonies arising from infections in April 1961 discharged ascospores in 32 days, whereas infections made 1 month later did not produce sporulating colonies until 54-58 days later. The full life cycle of P. parilis took 62-77 days when inoculations were made in May 196 1.

Anatomical changes induced by triazoles in wheat seedlings

1988 ◽  
Vol 66 (6) ◽  
pp. 1178-1185 ◽  
Author(s):  
J. Gao ◽  
G. Hofstra ◽  
R. A. Fletcher
Keyword(s):  
Triticum Aestivum L ◽  
Chlorophyll Synthesis ◽  
Epidermal Cells ◽  
Vascular Bundles ◽  
Mesophyll Cells ◽  
Wheat Seedlings ◽  
Anatomical Changes ◽  
Subsidiary Cells ◽  
Wheat Leaves ◽  
Stimulation Of

The triazoles triadimefon and S-3307, applied as seed treatments at two concentrations each (0.1 and 1.0, and 0.001 and 0.01 g active ingredient/kg of seed, respectively), increased epicuticular wax and reduced the length but increased the width and thickness of wheat leaves (Triticum aestivum L. cv. Glenlea). Mesophyll cells of treated leaves were thicker than those of controls and there were more layers of cells around the median and lateral vascular bundles of leaves treated with the higher concentration of S-3307. The length of epidermal cells was reduced and the width was increased by both triazoles; the depth of epidermal cells was increased by the higher concentration of triadimefon only. S-3307 increased the number of vascular bundles, whereas triadimefon at the higher concentration increased their diameter. Both concentrations of S-3307 reduced the length of trichomes. The two triazoles increased chloroplast size along both the long and short axes. Compared with those of controls, the stomata in the triadimefon-treated leaves were constricted and sunken, whereas in S-3307 treated leaves the subsidiary cells were wider. The effects of the triazoles observed in this study may account in part for several plant growth regulatory activities reported earlier, including growth retardation, stimulation of chlorophyll synthesis, and protection against injury from water stress.

scholarly journals Posidonia oceanica molecular adaptation to the light environment

2015 ◽  
Author(s):  
Gabriele Procaccini ◽  
Emanuela Dattolo ◽  
Chiara Lauritano ◽  
Miriam Ruocco ◽  
Lazaro Marin-Guirao
Keyword(s):  
Environmental Changes ◽  
Light Availability ◽  
Posidonia Oceanica ◽  
Light Sensitivity ◽  
Light Environment ◽  
Molecular Adaptation ◽  
Important Species ◽  
Light Regimes ◽  
Seagrass Meadows ◽  
The Impact

Seagrass meadows are among the most productive ecosystems, with Posidonia oceanica being the most important species along the Mediterranean coastline. This species forms extensive mono-specific meadows that are extremely sensitive to medium-high levels of disturbance and are being threatened by fast environmental changes caused by global warming and increasing human activities. The impact can either reflect in higher turbidity along the water column and in increased UV radiation, making the light availability one of the most important factors affecting P. oceanica distribution. Plants developed mechanisms of adaptations at multiple levels to track and cope with fluctuations and changes in the light environment. At molecular level, the modulation of gene expression in response to environmental changes allows plants to optimize the utilization of light energy for growth and to prevent damages due to its excess. To detect the relevant molecular adaptation strategies evolved by P. oceanica and to assess the plasticity showed in the acclimation under different light regimes, we are employing studies both in natural and controlled conditions. Here, we describe the differences in photo acclimation of plants living along the bathymetric cline observed in field and in a common garden experiment in mesocosms, after the exposition to contrasting light regimes. Using a transcriptional approach (both RT -qPCR and RNA-seq) coupled with a physiological one, we are also testing potential divergences existing among populations and individuals related to light sensitivity. These data should supply new insights for the management of seagrasses ecosystems, for the development of most successful transplantation strategies and ultimately for conservation of biodiversity of these precious ecosystems.

Functional leaf anatomy and ultrastructure in a marine angiosperm, Syringodium isoetifolium (Aschers.) Dandy (Cymodoceaceae)

1993 ◽  
Vol 44 (1) ◽  
pp. 59 ◽  
Author(s):  
J Kuo
Keyword(s):  
Vascular Bundle ◽  
Leaf Blade ◽  
Small Region ◽  
Total Surface Area ◽  
Epidermal Cells ◽  
Secretory Cells ◽  
Vascular Bundles ◽  
Mesophyll Cells ◽  
Vascular Tissues ◽  
Syringodium Isoetifolium

The terete leaf blade of Syringodium isoetifolium (Aschers.) Dandy from south-western Australia has uniformly small epidermal cells and a few large secretory cells. Mesophyll tissues contain several air lacunae, a central longitudinal vascular bundle, and eight to twelve peripheral longitudinal vascular bundles, but no fibre bundles. The total volume of air lacunae is about 10% that of the leaf blades, but the total surface area of air lacunae is similar to that of leaf blades. The leaf cuticle appears as a thin, electron-transparent layer. Leaf-blade epidermal cells have a large central vacuole and peripheral cytoplasm containing many chloroplasts that lack starch grains. Wall ingrowths are absent. However, the small region between the walls and the plasmalemma could play an important role in nutrient absorption. Plasmodesmata appear to be absent between adjacent epidermal cells, and also between epidermal and mesophyll cells, suggesting that there is only an apoplastic pathway for the transport of photosynthate to the vascular tissues. Each vascular bundle is surrounded by a layer of sheath cells, which are characterized by the presence of suberized lamellae in their walls. These may act to reduce the apoplastic exchange of solutes and water between the mesophyll and vascular tissues. Xylem elements, represented by large lumens and intensely hydrolysed walls, may not be present in all peripheral vascular bundles. Two types of sieve elements occur in S. isoetifolium leaf blades: normal thin-walled ones with large lumens, and thick-walled ones with reduced lumens, representing the photophloem and the metaphloem, respectively.

scholarly journals Posidonia oceanica as a Source of Chromophoric Dissolved Organic Matter for the Oligotrophic NW Mediterranean Coast

2020 ◽  
Vol 8 (11) ◽  
pp. 911
Author(s):  
Francesca Iuculano ◽  
Carlos M. Duarte ◽  
Jaime Otero ◽  
Xosé Antón Álvarez-Salgado ◽  
Susana Agustí
Keyword(s):  
Organic Matter ◽  
Dissolved Organic Matter ◽  
Rocky Shore ◽  
Posidonia Oceanica ◽  
Mediterranean Coast ◽  
Balearic Islands ◽  
Chromophoric Dissolved Organic Matter ◽  
Absorption Increase ◽  
Seagrass Meadows ◽  
Nw Mediterranean

Posidonia oceanica is a well-recognized source of dissolved organic matter (DOM) derived from exudation and leaching of seagrass leaves, but little is known about its impact on the chromophoric fraction of DOM (CDOM). In this study, we monitored for two years the optical properties of CDOM in two contrasting sites in the Mallorca Coast (Balearic Islands). One site was a rocky shore free of seagrass meadows, and the second site was characterized by the accumulation of non-living seagrass material in the form of banquettes. On average, the integrated color over the 250–600 nm range was almost 6-fold higher in the beach compared with the rocky shore. Furthermore, the shapes of the CDOM spectra in the two sites were also different. A short incubation experiment suggested that the spectral differences were due to leaching from P. oceanica leaf decomposition. Furthermore, occasionally the spectra of P. oceanica was distorted by a marked absorption increase at wavelength < 265 nm, presumably related to the release of hydrogen sulfide (HS−) associated with the anaerobic decomposition of seagrass leaves within the banquettes. Our results provide the first evidence that P. oceanica is a source of CDOM to the surrounding waters.

scholarly journals Adaptability and leaf anatomical features in oil palm seedlings produced by embryo rescue and pre-germinated seeds

2010 ◽  
Vol 22 (3) ◽  
pp. 209-215 ◽  
Author(s):  
Zanderluce G. Luis ◽  
Kadja Milena G. Bezerra ◽  
Jonny Everson Scherwinski-Pereira
Keyword(s):  
Oil Palm ◽  
Embryo Rescue ◽  
Morphological Characteristics ◽  
Growth Conditions ◽  
Epidermal Cells ◽  
In Vitro Cultivation ◽  
Vascular Bundles ◽  
Anatomical Plasticity ◽  
Germinated Seeds

Changes in the leaf structure of plants grown in different conditions have been reported, such as increase in size and density of stomata and reduction in stomatal control, amount of epicuticular wax, and mesophyll thickness, with a high diversity of intercellular spaces. However, these changes are highly variable depending on the physiological and morphological characteristics of each species. The objective of this work was to analyze the adaptability and anatomical plasticity of oil palm seedlings produced after embryo rescue and pre-germinated seeds. Expanded leaves were prepared for evaluation of morphometric data and anatomical structures. It was verified that the environmental conditions in vitro negatively influenced the stomata density, epidermal and hypodermal thickness, and the values for the expansion cells and leaf mesophile. Anatomically, the oil palm leaves present the same tissues composition in both growth conditions, with uniseriate epidermal cells, and tetracitic stomata occurring in both epidermal surfaces. Epidermal cells from in vitro plants are thinner than ones from greenhouse. The midrib of leaves from greenhouse plants are more developed and is composed by only one central vascular bundle, while plants from in vitro cultivation developed three to four collateral vascular bundles.

scholarly journals Trait gradients inform predictions of seagrass meadows changes to future warming

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Arianna Pansini ◽  
Gabriella La Manna ◽  
Federico Pinna ◽  
Patrizia Stipcich ◽  
Giulia Ceccherelli
Keyword(s):  
Global Warming ◽  
Posidonia Oceanica ◽  
Shoot Density ◽  
Western Mediterranean ◽  
Seagrass Meadows ◽  
Western Mediterranean Sea ◽  
Seagrass Ecosystem ◽  
Rhizome Biomass ◽  
And Function ◽  
Time Substitution

AbstractComparing populations across temperature gradients can inform how global warming will impact the structure and function of ecosystems. Shoot density, morphometry and productivity of the seagrass Posidonia oceanica to temperature variation was quantified at eight locations in Sardinia (western Mediterranean Sea) along a natural sea surface temperature (SST) gradient. The locations are spanned for a narrow range of latitude (1.5°), allowing the minimization of the effect of eventual photoperiod variability. Mean SST predicted P. oceanica meadow structure, with increased temperature correlated with higher shoot density, but lower leaf and rhizome width, and rhizome biomass. Chlorophyll a (Chl-a) strongly impacted seagrass traits independent of SST. Disentangling the effects of SST and Chl-a on seagrass meadow shoot density revealed that they work independently, but in the same direction with potential synergism. Space-for-time substitution predicts that global warming will trigger denser seagrass meadows with slender shoots, fewer leaves, and strongly impact seagrass ecosystem. Future investigations should evaluate if global warming will erode the ecosystem services provided by seagrass meadows.

scholarly journals Feeding preferences of amphipod crustaceans Ampithoe ramondi and Gammarella fucicola for Posidonia oceanica seeds and leaves

2019 ◽  
Vol 83 (4) ◽  
pp. 349
Author(s):  
Inés Castejón-Silvo ◽  
Damià Jaume ◽  
Jorge Terrados
Keyword(s):  
Direct Evidence ◽  
Paracentrotus Lividus ◽  
Posidonia Oceanica ◽  
Feeding Preferences ◽  
Research Attention ◽  
Seagrass Meadows ◽  
Idotea Baltica ◽  
Published Evidence ◽  
Sarpa Salpa

The functional importance of herbivory in seagrass beds is highly variable among systems. In Mediterranean seagrass meadows, macroherbivores, such as the fish Sarpa salpa and the sea urchin Paracentrotus lividus, have received most research attention, so published evidence highlights their importance in seagrass consumption. The role of small crustaceans in seagrass consumption remains less studied in the region. Herbivory on Posidonia oceanica seeds has not previously been reported. In turn, crustacean herbivory on P. oceanica leaves is broadly recognized, although the species feeding on the seagrass are mostly unknown (except for Idotea baltica). This work evaluates P. oceanica consumption by two species of amphipod crustaceans commonly found in seagrass meadows. Ampithoe ramondi and Gammarella fucicola actively feed on P. oceanica leaves and seeds. Both species preferred seeds to leaves only when the seed coat was damaged. This study provides the first direct evidence of consumption of P. oceanica seeds by the two named amphipod crustaceans, and confirms that they also consume leaves of this seagrass species.

Sign in / Sign up

Export Citation Format

Share Document