Cell wall metabolism during ripening and storage of nonclimacteric sour cherry (Prunus cerasus l., cv. Kántorjánosi)

Ripeness: The colour of green (ripeness stage I), pit hardening (II), light red (a, b) (III, IV), red (V) and dark red (VI) sour cherry fruits ( Prunus cerasus cv. Kántorjánosi) were characterised by CIELAB L*, a* and b* values. L* and b* decreased as a function of ripeness, a* intensively increased between green (I) and pit hardening (II) stages. The cell wall of green fruit was intact, but the electron dense cytoplasm concentrated along the cell wall and showed a number of degradation signs. The pit hardening stage (II) resulted in more structural break down in the cytoplasm and in the cell wall. Large numbers of plastoglobuli were in the plastids resulting in chloroplast-gerontoplast conformation. The most striking feature of light red fruits is the dissolution of the walls. Middle lamellae almost completely disappeared. In ripe fruits, the wall degradation was even more prominent. The regular structure of the cytoplasm had almost completely disappeared. The total pectin content between pit hardening and light red stages was the highest. The autolysis of pectin increased between pit hardening (II) and light red-a stage (III), then it slowly decreased. The largest activity of β-galactosidase was in the green (I) stage, and then in the pit hardening stage (II) it suddenly decreased. In light red-a/b (III/IV) stages the activity of β-galactosidase again started to increase. The activity of polygalacturonase did not depend on the grade of ripeness. Storage: In the first period of storage, the activity of β-galactosidase and polygalacturonase of sour cherry decreased, then in the second period of storage increased

Flowering phenology, floral display and reproductive success of Iris sibirica

Numerous experiments have suggested that in many species higher floral display can be more attractive for pollinators, but the possibility of between-flower self-pollination, namely geitonogamy may reduce the floral longevity, the fitness of both individuals and the offspring. In this study we investigated how phenological parameters (mainly floral display) change temporally and how they affect the female reproductive success of cymose Iris sibirica. We found that in blooming sequence of both individuals and the population 3 sections can be separated. The number of levels and flowers per stalks on the plants observed was very variable yearly. Female reproductive success parameters (fruit set and seed set) showed intra- and interannual variations, which were probably due to intra-plant resource allocation

Metal contamination in urban street sediment in Pisa (Italy) can affect the production of antioxidant metabolites in Taraxacum officinale Weber

Taraxacum officinaleWeber (dandelion) is a very ubiquitous species and it can grow in urban environments on metal polluted sediments deposited in the gutters. This study represents a preliminary step to verify the presence of metals in sediments collected in urban streets in Pisa and to assess the alteration in dandelion metabolites in order to understand its adaptation to polluted environments. The soil and sediments were collected at three urban streets and analyzed for total and extractable Cr, Pb, Cu, Ni, Zn. The total values of Pb and Zn in street sediments exceeded the limits for residential areas of soils. Zn was the most mobile of the metals analysed. Floating cultivations trials were set up with dandelion seedlings and street sediments. The metals were analysed in roots and leaves. Antioxidant power, anthocyanins, polyphenols, nonprotein thiols (NP-TH) and chlorophylls were measured in dandelion leaves. The first two parameters (anthocyanins and antioxidant power) were higher in the polluted samples compared to the control; chlorophyll content was lower in the treated samples, whereas NP-TH showed no differences. NP-TH groups determined in roots were associated with the root content of Zn and Pb. These results indicate that dandelion can tolerate plant stress by altering its metabolite conten