638 research outputs found
Le macchine molecolari deputate alla costruzione e modificazione delle pareti delle cellule vegetali
No full textLe pareti sono uno degli elementi funzionali caratterizzanti delle cellule vegetali, dove biosintesi, assemblaggio e rimodellamento sono sotto stretto controllo genetico e ambientale. La principale macchina molecolare coinvolta è la cellulosa sintasi, la cui attività permette la polimerizzazione degli zuccheri in cellulosa e la cui interazione con il citoscheletro determina l'accrescimento e la forma definitiva delle cellule mature. Altri meccanismi enzimatici sono ad oggi sotto investigazione per comprendere meglio come avvengono la costruzione e le modificazioni di questa struttura
cellulare, che garantisce alle piante il necessario sostegno meccanico e fornisce al contempo all'uomo materie prime come la cellulosa ed il legno.The cell wall is one of the functional elements of the plant cell, where biosynthesis, assembly and remodeling are under genetic and environmental control. The main molecular machinery involved is cellulose synthase, that polymerizes sugars into cellulose and interacts with the cytoskeleton to guarantee growth and shape of the mature cell. Other enzymatic mechanisms are being elucidated, that explain how this fundamental cellular structure is built and modified. Research interest in this field is motivated by the importance of this structure both for the plant’s mechanical properties and as a source of raw materials such as cellulose and timber
Total phenolic content in brown algae from the Sicilian coast
No full textPhlorotannins are polyphenolic secondary metabolites found in almost all brown algae that function as defense against grazers, pathogens and epiphytes but are also involved in photoprotection mechanisms. These com- pounds, produced in the Golgi apparatus, are accumulated in cytoplasm, within vesicules called physodes, or bound to the cell wall. The concentration of phlorotannins differs within and between species, shows geograph- ical variations but may be also affected by abiotic or biotic factors. We present here an overview of the studies carried out on total phenolic content in brown algae collected along the north-western coast of Sicily. The aims of these studies were in particular a) to analyse total phenolic content in four Mediterranean brown algae (Cys toseira amentacea, Cystoseira compressa, Dictyopteris polypodioides and Padina pavonica), b) to follow the sea- sonal changes in total phenolic content in D. polypodioides and C. amentacea and c) to test the effects of temperature on total phenolic content of C. amentacea. Results showed signiicant differences in total phenolic content between leathery and sheet-like algae and also within each morphological group. Among the four species, the sheet-like alga D. polypodioides showed the highest concentration of phenolic compounds. Differ- ences in the seasonal pattern of total phenolic content and in the period of maximum production were observed between D. polypodioides and C. amentacea. In D. polypodioides the peak was observed during winter and autumn whereas for C. amentacea the peak was observed during spring and summer. Moreover, C. amentacea responded signiicantly to the exposition to an increase of temperature, suggesting that increasing global temperatures predicted in the coming century might have effects on the chemical defences and then on the trophic interactions of these algae. The results of these studies seem to conirm that total phenolic content in brown algae is a re- sponse to a combination of several factors. However, due to the complexity of total phenolic content responses in brown algae and the multiple roles of phlorotannins, for a better understanding of this process, it is still nec- essary to identify which types of phlorotannins are responsible for the different activities in order to clarify who does what. Therefore, studies are currently in progress in order to characterize phlorotannins in some species belonging to the Fucales and Dictyotales and to test their biological activities
Effects of foliar application of glycine betaine and chitosan on Puccinellia distans (Jacq.) Parl. subjected to salt stress
Get PDFIntroduction:Using brackish water for irrigation may expose turfgrasses to salinity stress.Employing the best treatments to maintain high-quality turfs under saline conditions is animportant requirement for turfgrass management.Methods:We tested the response of ahalophyte grass,Puccinellia distans, to irrigation with saline solutions and to foliarapplication of two osmoprotectants, such as glycine betaine (GB) or chitosan (CH). Plantswere grown in pots under controlled conditions and irrigated with 200 mM or 600 mM ofNaCl solutions. The response to salinity treatments and osmoprotectant application wasevaluated after 90 days by measuring leaffiring, leaf density, shoot length and biomass, rootlength, and shoot water potential.Results:Increasing salinity reduced shoot density, shootand root length, shoot water potential, and increased leaffiring and shoot solute potential at200 mM of NaCl. These effects were more pronounced at 600 mM of NaCl. Application ofGB greatly increased shoot growth traits at 200 mM of NaCl and also showed beneficialeffects on most traits at 600 mM. Application of CH showed positive effects only on leaffiring and leaf water potential at 600 mM.Conclusions:Our results show thatP. distanscantolerate high levels of salt stress, which can be best alleviated by GB treatmen
Monitoring of alien aquatic plants in the inland waters of Sicily (Italy)
Get PDFUpdated and reliable data on the presence and distribution of alien aquatic
plant species in Sicily are lacking, and there is a need to fill this gap for a proper and
efficient management of freshwater ecosystems and biodiversity. This paper reviews
the available knowledge about alien aquatic vascular plants in the inland waters of
Sicily (Italy). The aim is to provide an updated checklist, as a first step in the study of
the impact of those plants on the native species and ecosystems of this Mediterranean
island. The paper focuses on the strictly aquatic species (hydrophytes), excluding emergent
macrophytes. Four species were listed, all of them free-floating and with American
origin. Most of them occur within protected areas, and their introduction in the island
appears to be anthropogenic. A set of functional traits of the alien species, such as relative
growth rate, leaf mass per area, nitrogen and carbon content, were screened. These
traits are useful for assessing the species invasive potential compared to native ones
Is in vitro micrografting a possible valid alternative to traditional micropropagation in Cactaceae? Pelecyphora aselliformis as a case study
Get PDFSeveral taxa of Cactaceae are endangered by overcollection for commercial purposes, and most of the family is included in the Convention on International Trade in Endangered Species of Fauna and Flora (CITES). Micropropagation may play a key role to keep the pressure off wild populations and contribute to ex situ conservation of endangered taxa. One of the limits of micropropagation is the species-specific requirement of plant regulators for each taxon and sometimes even for different genotypes. With the micrografting technique the rootstock directly provides the scion with the necessary hormonal requirements. In this paper we present data on in vitro grafting of Pelecyphora aselliformis Ehrenberg, an Appendix I CITES listed species critically endangered and sought after by the horticultural trade, on micropropagated Opuntia ficus-indica Miller. Apical and sub-apical scions of P. aselliformis were used to perform micrografting with a successful rate of 97 and 81 % respectively. Survival rate after ex vivo transfer was 85 %. We hypothesize that this method could be applied to other endangered, slow growing taxa of Cactaceae thus contributing to the conservation of this endangered family.Several taxa of Cactaceae are endangered by overcollection for commercial purposes, and most of the family is included in the Convention on International Trade in Endangered Species of Fauna and Flora (CITES). Micropropagation may play a key role to keep the pressure off wild populations and contribute to ex situ conservation of endangered taxa. One of the limits of micropropagation is the species-specific requirement of plant regulators for each taxon and sometimes even for different genotypes. With the micrografting technique the rootstock directly provides the scion with the necessary hormonal requirements. In this paper we present data on in vitro grafting of Pelecyphora aselliformis Ehrenberg, an Appendix I CITES listed species critically endangered and sought after by the horticultural trade, on micropropagated Opuntia ficus-indica Miller. Apical and sub-apical scions of P. aselliformis were used to perform micrografting with a successful rate of 97 and 81 % respectively. Survival rate after ex vivo transfer was 85 %. We hypothesize that this method could be applied to other endangered, slow growing taxa of Cactaceae thus contributing to the conservation of this endangered family
Nuove frontiere della fotosintesi clorofilliana: la foglia artificiale
Get PDFPer molti anni la scienza ha tentato di riprodurre il processo fotosintetico delle piante,
che permette di utilizzare la luce del sole e l'anidride carbonica dell'atmosfera per produrre gli zuccheri
necessari al loro metabolismo. Nella primavera del 2010 sui quotidiani compare la notizia rivoluzionaria
della creazione di una foglia artificiale, capace di trasformare la luce in una fonte di
energia utilizzabile dall'uomo. Su quali principi si basa questa scoperta? Quanto ha di analogo con
i processi che avvengono nelle foglie? E quanto siamo vicini all'applicazione su vasta scala di questa
innovazione tecnologica
Water Potential Gradients between Old and Developing Leaves in Lithops (Aizoaceae).
Get PDFLithops plants consist of a pair of opposite succulent leaves inserted on a short stem. The apical meristem produces a new pair of leaves
within the old one every growing season, recycling water from the old leaves. Since there are no data on water relations between the two
pairs of leaves, we measured leaf water potential at different stages of development with a pressure chamber. Osmotic potential of cell sap
was measured with a cryoscopic osmometer and turgor pressure was calculated indirectly. Leaf water potentials were never very low even
though plants were not irrigated. In old leaves water potential ranged between -0.5 and -0.28 MPa. In young leaves water potential
increased with size from -1.05 to -0.5 MPa and was always lower than in the corresponding old leaves. The water potential gradient
between old and new leaves was steeper in the early stages of development (0.6 MPa) and gradually decreased (0.15 MPa) when young
leaves had almost completed their expansion. Our data show that in Lithops water movement from old to young leaves occurs according
to a water potential gradient. The maintenance of this gradient may be ascribed to differences in turgor pressure, due to the more elastic
and plastic walls of cells of young leaves. The possibility to perform a complete life cycle without external water supply is an extreme
adaptation to the arid environment where Lithops grows
VARIAZIONI DI ALCUNI PARAMETRI FISIOLOGICI IN OLEA EUROPAEA ‘BIANCOLILLA’ COLTIVATA IN DIFFERENTI REGIMI IRRIGUI
No full textInvestigating the ecology of Chara cf. baltica (Characeae) in the Lago Preola ecosystem (Sicily, Italy)
No full textLago Preola is a small lake, located in SW Sicily, in a karstic depression within the Nature Reserve “Lago Preola e Gorghi Tondi”. With about 33 ha (maximum depth: 2 m), it is the widest of the 5 natural lakes occurring in the Reserve. The presence of species of conservation concern (e.g., Emys trinacris, the Sicilian Pond Turtle, and several migratory birds), but also of invasive alien species (e.g., Procambarus clarckii, the Red Swamp Crayfish), has been reported for the area. The flora of terrestrial habitats surrounding the basins has been studied extensively, while the aquatic flora and vegetation have not been studied in detail. The coastal aquifer supplying groundwater to the study area lakes has shown fluctuations in the last decades: Curry et al. (2016) reported that in 2000/2001 Lago Preola dried out completely during the summer drought. Irrigation well pumpage was reduced in 2004, and ceased in 2008, which in combination with abundant precipitation has since resulted in high, stable lake levels (Curry et al. 2016). The finding of a Chara, provisionally identified as C. baltica Bruzelius (troia et al. 2018), has led us to study the distribution and ecology of the species in this area. C. baltica forms a thick monospecific meadow along the shore at the sampling site. In Summer 2018 the water was slightly brackish (conductivity ca. 4 mS/cm) and slightly alkaline (pH ca. 9). At an analogous sampling site in the nearby lago Murana (conductivity ca. 3 mS/cm, pH ca. 8.6), macrophyte vegetation was instead characterized by a monospecific meadow of the angiosperm Najas marina L. s.l., not reported up to now for the Reserve. In the framework of providing an isotopic baseline for future studies on the ecophysiology of these two macrophytes and on trophic relations within the water basins (rodrigo et al. 2016), we have started analysing carbon and nitrogen stable isotope composition. Macrophytes for these analyses were sampled at ca. 2 m from the shore, at a depth of approximately 0.5 m. Samples were dried to constant weight, powdered, and analysed with an isotope ratio mass spectrometer and an elemental analyser
The ancient irrigation system of the Palermo Plain (Sicily, Italy) as a substitute ecosystem: preliminary investigations on its aquatic flora
No full textMany cities around the world are expanding, including in their perimeters green and blues spaces that could be crucial for the maintaining of biodiversity. Urban waterbodies are generally created to provide other services, but correctly managed they can provide also relevant ecosystem services. The Palermo Plain was characterized, in the past centuries, by several wetlands that were progressively destroyed (or “reclaimed”). The ancient irrigation system, probably set during the Arab domination (IX-XI century A.D.), became a substitute ecosystem able to host a significant biodiversity. Our research focused on the remains of this system, scattered in the relictual green areas of the Plain, and especially on typical open cisterns, named (with a term of Arabic origin) “gebbie”; we checked the presence of strictly aquatic flora (vascular plants and charophytes), taking also into account some water parameters (conductivity, pH and hydroperiod) and the type of management of these water bodies. The floristic richness of these urban reservoirs appears to be generally low; however, they sometimes support rare species, or species otherwise disappeared from the Plain. If well managed, they have the potential to support a much greater biodiversity than they currently do; on the contary, abandoned “gebbie” are the poorest ones
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