Maria Rita Melati

The mapping of stress in the predominant plantsin the city of Palermo by lead dosage

Many plants react to pollutants in the atmosphere andcan consequentely be used to examine air quality.A distinction is made between bioindicator,bioaccumulator and hiperaccumulator and biomonitorplants.Given the encouraging results of a study to monitorstress caused by pollution in the city of Palermo(Sicily), we decided to carry out a survey ofpollutants, by examining some “passive bioindicatorplants”, which grow naturally or which had long agobeen planted in the city. The species chosen were:Eucaliptus camaldulensis Dehnh.; Pinuspinea L.; Platanus hybrida Brot, examples ofwhich are found all over the city.Biostructural and spectrophotometry analyses werecarried out on the leaf and pollen samples, payingparticular attention to lead. Most damage (cytologicalalterations and lead accumulation) was found in thepine; morphological and cytological parameters arehighly unspecific but positively correlated with leadpresence in plant structures.

Examples of seed dispersal by entomochory

Summary For millions of years, day and night, year after year, fruits and seeds have migrated across the globe, ensuring the survival of genera and species. And only in this way will future generat...

Stress-induced cytological and chemical adaptations in Cupressus plants from an urban area of Palermo (Italy)

Abstract We studied stress-induced cytological and chemical adaptations in Cupressus pollens and needles from the area of Palermo (Sicily, Italy), in polluted and control sites (unpolluted) of urban and suburban areas. Pollen and needle chemical composition were investigated to provide an indicator of contamination of the trees, which were also examined structurally throughout one year. The concentration of particulate with lead was found to be significantly higher in plants at the polluted traffic site. Lead is one of the worst particulate pollutants in cities, especially in the winter season. In trees from the polluted site, all structural analysis revealed displasies. Structural changes, observed in trees from polluted sites, are most likely caused by the toxic effects of various pollutants, for example particulate, because fine particulate, with metals, is on the rise at present. We studied the effects on the pollen with an optical microscope, a scanning electron microscope (SEM) and cytochemical staining of esterases and acid phosphatase.

Presence of esterase inPinaceae pollen

General esterases, like wall heterologous enzymes, may be implicated in allergenic mechanisms. We cytochemically examined the presence of these enzymes, bearing in mind thatPinus spp. is often considered a possible cause of allergies. Positive esterase results in fungus spores were found on the strip of a volumetric sampler. Data are reported here, together with the hypothesis of a possible esterase-allergenic link regarding fungus spores.

Effect of magnetic fields on seedling growth and cyto-morphogenesis in Sinapis alba L.

Abstract The magnetic treatment presented in this study could be included among cultivation procedures aimed at a better utilisation of plant species. The treatment enhances seedling growth (expressed in fresh weight or in length of the hypocotyl) stimulates morphogenic events (premature differentiation of the reticulate xylem elements, increased wall thickness, reduction of the xylem diameter, increase of acid phosphatases) and renders the seedling batches more homogeneous. Our study demonstrates that exposure to weak (30 mT) magnetic fields for short periods (15, 30, 60 seconds) stimulates seedling growth.

Pollen grain stereostructure, viability and germination ; correlation with temperature of Antirrhinum tortuosum Bosc

Summary The present article describes the pollen grain stereostructure (SEM), viability with fluorescein diacetate, and correlation between the temperature of 5°C and 25°C and the germination and pollen tube length of Antirrhinum tortuosum Bosc, collected in Cefalu (Palermo). We have shown that the growth of the pollen tube is related to the temperature and that the quantity of pollen showing fluorochromasia corresponds with that of the functional, germinated pollen.

Colchicine-induced changes in the growth and secondary wall deposition of cotyledonless radish seedlings

Summary Colchicine (at 0.2 %) reduces the percentage of germination of radish seeds and influence the growth, morphogenesis and differentiation of xylem elements of the cotyledonless seedling. Colchicine does not significantly influence either the fresh or the dry weight but it does reduce the length of the hypocotyl, root and the developing xylem elements. Hypocotyl diameter increases compared to the control. Root growth rate decreases and the differentiation of xylem elements advances toward the apex. The reduction in cell extension is accompanied by an increase in cell diameter and it is clear that colchicine has an effect on cellular expansion and cell shape. Treatment with colchicine changes the deposition pattern of the secondary wall and results in conspicuous irregularities in the form and distribution of wall thickening. The cotyledonless seedlings cultured in colchicine for 24 hours and successively transferred to water, show a modification of the xylem differentiation and of the wall deposition...

Effect of treatments of different duration with NaCl on growth, differentiation and esterase activity in excised radish cotyledons

Summary Radish etiolated cotyledons were excised from the seed after 24 hours of imbibition and incubated for different times on filter paper satured with NaCl solutions or water. After the incubation of different times in NaCl, the cotyledons were thoroughly rinsed in water and grown in darkness on filter paper satured with distilled water. Continuous presence of NaCl is not a prerequisite for optimal growth. Several effects of the NaCl solutions are less intensive if the cotyledons are treated with NaCl for a relatively short time and then grown in water.

Growth, histogenesis and morphogenesis in Raphanus sativus L. under water stress. The seedling

SummaryRadish etiolated seedlings were subjected to water stress using mannitol as osmoticum. As the mannitol concentration increased, measurements were made on growth, relative water content (RWC) and xylem elements. The xylem pattern was also observed.The presence of mannitol in the culture medium strongly modifies the fresh weight, water content and the length of radish seedlings and their hypocotyl and root morphogenesis, while dry weight was not significantly affected. At concentrations above 4% mannitol, growth was greatly reduced after 48 and 72 hours of incubation. Xylogenesis and wall deposition patterns were altered at severe water stress. Growth was more sensitive than cell wall synthesis to stress.Based on the water stress experiments it is concluded that the differences in plant water status caused differences in elongation, expansion of xylem elements, cell division and xylogenesis. The sensitivity of response to changes caused by water stress indicates the direct role of water in growth, mo...