Teresa Tykarska

Direct plant development from microspore-derived embryos of winter oilseed rape Brassica napus L. ssp. oleifera (DC.) Metzger

The influence of temperature/photoperiod treatment and gibberellic acid concentration (0, 0.1 or 1.0 mg/l) on direct conversion of microspore-derived embryos (MDEs) to plantlets of winter oilseed rape was investigated. Physiologically mature, 21-day-old MDEs were transferred to a solid B5 medium supplemented with gibberellic acid, and cultured at 24 °C, 4 °C or 1 °C for 14 days, and then at 24 °C for the next 21 days. Low temperature was linked with short photoperiod (8 h light/16 h dark), and high temperature was linked with long photoperiod (16 h light/8 h dark). The highest embryo conversion rate was at 1 °C with over 70%, compared to<20% at 4 °C. Two-way analysis of variance confirmed the significance of the effect of temperature/photoperiod treatment. By contrast, gibberellic acid concentration had no significant effect on stimulation of shoot development from apical meristems of MDEs. Roots developed from apical root meristems of MDEs very easily. The best obtained conversion rate of MDEs induced with cold treatment at1 °C for 14 days was 86.5%. Observations on morphological development of MDEs showed clear differences in reaction at various temperature/photoperiod treatments.

SOMATIC EMBRYOGENESIS OF GENTIANA CRUCIATA (L.): HISTOLOGICAL AND ULTRASTRUCTURAL CHANGES IN SEEDLING HYPOCOTYL EXPLANT

SummaryStructure and ultrastructure changes that occurred during tissue culture of upper explants of hypocotyl (adjacent to cotyledons) of 10-d-old seedlings of Gentiana cruciata were studied. The explants were cultured on Murashige and Skoog induction medium supplemented with 1.0 mg l−1 dicamba +0.1 mg l−1 naphthaleneacetic acid +2.0 mg l−1 benzyladenine +80.0 mg l−1 adenine sulfate. The initial response of the explant and callus formation were ultrastructurally analyzed during the first 11 d of culture. After 6–8 wk, various methods were employed to collect evidence of indirect somatic embryogenesis. After 48 h of culture, the earliest cell response was cell division of epidermis and primary cortex. There were numerous disturbances of karyo- and cytokinesis, leading to formation of multinuclear cells. With time, the divisions ceased, and cortex cells underwent strong expansion, vacuolization and degradation. About the 6th day of culture, callus tissue proliferated and the initial divisions of vascular cylinder cells were observed. Their division appeared normal. Cells originating from that tissue were small, weakly vacuolated, with dense cytoplasm containing active-looking cell organelles. Numerous divisions occurred in the vascular cylinder, which led to its expansion and the formation of embryogenic callus tissue. During the 6–8th wk of culture, in the proximal end of the explant, masses of somatic embryos were formed from outer parts of intensively proliferating tissue.

Visualization of the radicle within tee axis of developing and germinating Brassica napus L. embryos

Abstract A method is presented for visualizing the exact radicle territory within the developing embryo axes of Brassica napus L. (rape). The reactive dye, Procion Blue MX-R, when used for embryo axes in toto , showed a definite staining pattern. The basal boundary of the stained region (level L2) did not coincide with the basal radicle cap boundary (level L1), and, on average, 16 rhizodermal cells were observed between these boundaries in maturing and mature embryos. In all stages of developing embryos, from the torpedo stage to maturity, the embryo hypocotyl was not stained, and the stained region revealed the proper radicle territory. This conclusion was based on the following observations: (1) the staining patterns in the developing, developed and germinating embryos were similar; (2) direct observations of the basal part of the stained L1–L2 region demonstrated that its cells began fast elongation 24 hr after seed imbibition and began root hair formation just before the completion of elongation; (3) root hairs did not emerge after decapitation of the entire stained region which was done 24 hr after the beginning of seed imbibition; (4) at this time (24 hr post-initiation of imbibition) decapitation at level L1 stopped radicle growth for 24 hr, and hairs emerged in the apical portion of the axes; and (5) cross-sections of the L1–L2 zone of seedlings revealed a vascular system typical of root. Stainability is a complex reaction which combines interaction of the dye with the surface of radicle cells and its penetration into outer tissue cells of the radicle. Differential stainability of the hypocotyl and the radicle within the axes of developing and germinating B. napus L. embryos might be partially related to the presence of cuticle on the hypocotyl surface and its absence on the radicle surface.

Morphological and anatomical factors responsible for varied susceptibility of some species of spruce to infestation by spruce spider mie (Oligonychus ununguis Jacobi)

Differences in susceptibility to infestation by spruce spider mite of 3 investigated spruce species (Picea glauca ‘Conica’, P. pungens and P. omorika) may be due to features of anatomical and morphological structure of needles. In P. omorika, showing some resistance to the spruce spider mite, we noted lamellar structure of epidermal cell walls and extensive supporting tissues (hypodermis and sclerenchyma fibres) at the whole circumference of the needle.