Zvonimir Devidé

Triploidy in callus culture ofVicia faba L. investigated by the Giemsa C-banding technique

Callus tissue ofVicia faba has been grown from explants of immature embryos. The karyological analysis by the Giemsa C-banding technique has shown triploid and tri-aneuploid mitoses, all with an extra chromosome and with structurally altered karyotypes. Estimates of the amounts of interphase heterochromatin (chromocentres) indicate endopolyploidy up to 12 n.

Developmental aspects of long-term callus culture ofVicia faba L.

SummaryVicia faba callus line (VFS 1), isolated from expiants of immature embryo, grew satisfactorily onMurashige andSkoog complete medium with 1.38 μM 2,4-D, or with 0.92 μM 2,4-D to which 1.0 μM kinetin was added. It also grew well on the B 5 modified medium containing 2.3 μM 2,4-D and 25.0 μM kinetin. On the last of these media the cultures grew more uniformly and without necrosis. They also showed diminishing variation in polyploidy in favour of diploids and corresponding aneuploids (hypodiploids).After being cultured for nearly three years on MS containing 1.38 μM 2,4-D, 8–33% of cultures of VFS 1 were able to regenerate roots when transferred to either MS half strength with 5.37 μM NAA, or to a medium without 2,4-D, or else to media with the addition of kinetin only (in various concentrations).

Chromoplast structures in Thunbergia flowers

SummaryThe differentiation of tubulous chromoplasts in developing flowers ofThunbergia alata was studied by ultrastructural, pigment and protein analyses. The way of chromoplast formation in the mesophyll differed from that in the adaxial epidermis. While, in mesophyll cells, the chloroplasts were directly transformed into chromoplasts of the tubulous type, characteristic membranes and the tubular reticulum appeared in the adaxial epidermal cells, before the formation of tubules. The disappearance of the photosynthetic apparatus, the formation of membranous structures and the appearance of tubules were studied. The tubulous chromoplasts contained a 32 kDa protein, an unidentified carotene, and small quantities of lutein and β-carotene.

Ultrastructural studies of degradational processes in amitrole-damaged photosynthetic membranes

Abstract In several species of higher plants grown in light of high intensity, amitrole caused loss of pigments, degradation of thylakoids, and, hence, bleaching of the leaves. An unusual type of thylakoid degradation was observed in these leaves by electron microscopy of thin sections. The degradation started by the appearance of tightly stuck grana thylakoids and was followed by the appearance of perpendicularly oriented striation (period 12 nm) as observed in plastid cross sections. In plane sections, isometric particles (8 nm in diameter) arranged in a regular hexagonal pattern (with 12–13 nm spacing) were visible. Cytochemical methods (photooxidation of diaminobenzidine and photoreduction of thiocarbamyl nitrotetrazolium blue chloride) indicated that the activities of photosystems I and II gradually disappeared from the stuck thylakoids. These structures showed red fluorescence when observed under a fluorescence microscope, indicating the presence of chlorophylls or their degradation products.

Flower development inSpirodela polyrrhiza (Lemnaceae)

Flowering under experimental conditions inSpirodela polyrrhiza, and the development of the spatha, stamina and pistil are described and illustrated by microphotographs. During the development of the microsporangia the existence of the middle layer between endothecium and tapetum has been documented for the first time inLemnaceae.

Plastid transformation in greening scales of the onion bulb (Allium cepa, Alliaceae)

The greening of the upper part of the outerAllium cepa L. bulb scales, in particular along the vascular regions, is limited to the hypodermal cells in which typical leucoplasts are transformed to normal and functional chloroplasts. This process is light dependent and cannot afterwards be reversed or modified by darkness. The changes in fine structure are described and briefly discussed.