Agostino Stefani

Nuclear DNA content, chromatin organization and chromosome banding in brown and yellow seeds of Dasypyrum villosum (L.) P. Candargy

Banding patterns of metaphase chromosomes and nuclear DNA content in root meristematic cells of yellow and brown seeds of Dasypyrum villosum were determined. Microdensitometric evaluation of nuclear absorptions at different thresholds of optical density after Feulgen reaction indicated the organization of the chromatin in interphase nuclei, and allowed an evaluation of the amount of heterochromatin. These results were compared with those obtained after the application of banding techniques.

Morphology and germination of yellow and brown caryopses of Aegilops geniculata Roth (Gramineae) population from Italy

Abstract The germination percentage of Aegilops geniculata Roth caryopses was studied on four Italian populations (Pisa, Manfredonia, Catania and Simbirizzi). Observation of the germination trend was carried out at constant temperatures of 10°, 20° and 30°C, from maturation up to 60 days after harvesting. Spike, spikelet and caryopsis phenotypic characteristics were also studied. The populations of Pisa, Manfredonia and Simbirizzi presented two different types of caryopses: yellow caryopses - larger, heavier and composing roughly 60% of total—and brown caryopses—smaller and lighter in weight. The Catania population formed an exception in that brown caryopses were virtually absent (5%). This Sicilian accession also showed the largest spikelet size. Yellow caryopses germinated more rapidly than the dark ones, which were shown to be endowed with longer relative dormancy, above all at 10° and 30° C. Such a phenomenon allows the two types of caryopses to have a different germination ecology, thus providing A. ...

Puccinellia festucaeformis (Host) Parl.: Germinazione e crescita iniziale in funzione della salinità del substrato

Abstract Puccinellia festucaeformis (Host) Parl.: germination and early growth on different salt substrates. Germination behaviour of Puccinellia festucaeformis seeds and early growth of seedlings at different experimental conditions was analysed. The following growth substrates were utilized: NaCl, KCl, KNO3, MgCl2, MgSO4, Na2SO4, NaNO3, CaCl2 at the decreasing concentrations of 0.50, 0.25, 0.12, 0.06M. Caryopses were allowed to imbibe and grow at alternating temperatures (10°-20°C or 20°-30°C) in the dark for 3 days. Seedling were grown for 15 days, at controlled light and temperature conditions, in the same nutrient substrates as those used for the germination experiments. The germination experiments showed a high tolerance to salts up to 0.25M solution and for the whole range of MgSO4 concentrations. High growth temperatures increased the depressive effects of salt concentrations. Seedling growth was highly reduced when salt concentration was higher than 0.12M. High salt tolerance - maximum shoot and ...

Floral abnormalities in field grown “Tigrina” plants from xHaynaldoticum sardoum Meletti et Onnis (Gramineae)

Abstract A ‘tigrina’ mutant stock of xHaynaldoticum sardoum Meletti et Onnis grown under field conditions produced high frequency spikes with abnormal stamens and pistils. The abnormalities occurred mostly in the stamens, which frequently changed to either pseudoovaries, or leaf-shaped structures or, in extreme cases, did not form at all. The developmental abnormalities of the stamens resulted in male sterility in the whole or in part of the spike. It is proposed that the “tigrina” status changes the physiology of the plant (e.g. photosynthetic activity) in such a way that it responds with floral abnormalities brought about by environmental conditions which permit normal flower development in control (non-mutant) plants.

Assorbimento dopo colorazione al Fast-green di cellule della caliptra di Allium cepa localizzate in differenti regioni istologiche

Abstract Fast-green absorption of cells localized in different regions of Allium cepa root cap.—The nuclear and cytoplasmic protein content of two cell population (C2 = columella cells; P2 = peripheral cells) has been determined by Barr and Stroud cytophotometer after Fast-green staining (after DNA extraction and without DNA extraction). The collected data seem indicate that: 1) histone content is higher in nuclei of C2 cells than in nuclei of P2 ones; 2) acid proteins content is higher in nuclei of P2 cells than in those of C2 ones; 3) the cytoplasmic proteins of the two cell populations are quite different in their Fast-green reactivity.