This study is the first comparison of the morphology of pollen grains in ten cultivars of three species of the Taxus,
Torreya nucifera and Cephalotaxus harringtonia var. drupacea genera. The material came from the Botanical
Garden of Adam Mickiewicz University in Poznań, Poland. Each measurement sample consisted of 50 pollen
grains. In total, 750 pollen grains were analyzed. Light and electron scanning microscopy was used for the morphometric
observation and analysis of pollen grains. The pollen grains were inaperturate and classified as small
and medium-sized. They were prolate-spheroidal, subprolate to prolate in shape. The surface of the exine was
microverrucate-orbiculate, perforate in Cephalotaxus harringtonia var. drupacea, granulate-orbiculate, perforate
in all Taxus taxa and granulate-microverrucate-orbiculate, perforate in Torreya. The orbicules were rounded to
oval in surface view, and the size was considerably diversified. The pollen features were insufficient to distinguish
between individual Taxus members – only groups were identified. The values of the coefficient of variability of
three features (LA, SA and LA/SA) were significantly lower than the orbicule diameter. The pollen surface of all
Taxus specimens was similar, so it was not a good identification criterion. The pollen grains of the Taxus taxa
were smaller and had more orbicules than Cephalotaxus and Torreya. Palynological studies provided taxonomic
support for recognition of two different genera of the Cephalotaxaceae and Taxaceae families, which are closely
related.
Chromosome numbers for 15 taxa of Hieracium L. s.str. from Bulgaria, Greece, Macedonia, Poland, Romania
and Slovakia are given and their metaphase plates are illustrated. Chromosome numbers are published for the
first time for H. vagneri Pax s.str. (2n = 4x = 36), H. wiesbaurianum subsp. herculanum Zahn (2n = 4x = 36),
H. wiesbaurianum subsp. kelainephes Nyár. & Zahn (2n = 3x = 27), as well as for two undescribed species
of hybrid origin between H. umbellatum L. and H. wiesbaurianum s.lat. (2n = 3x = 27), and between H. sparsum
Friv. and H. schmidtii s.lat. (2n = 3x = 27), and for three undescribed species of the H. djimilense agg.
(2n = 3x = 27), H. heldreichii agg. (2n = 3x = 27), and H. sparsum agg. (2n = 3x = 27). Furthermore, the chromosome
numbers of two undescribed species of hybrid origin between H. umbellatum L. and H. wiesbaurianum
s.lat. (2n = 3x = 27), and between H. sparsum Friv. and H. schmidtii s.lat. (2n = 3x = 27) are given. A new,
tetraploid chromosome number is given for H. barbatum Tausch from the northernmost locality of the species
in Europe.
An efficient system of micropropagation via somatic embryogenesis from root-derived callus was established in
Arabica coffee (Coffea arabica L.). Twenty-six callus lines were induced on MS (Murashige and Skoog, 1962)
medium supplemented with combinations of NAA (0, 0.1, 0.5, 1 and 2 mg/L) plus BA (0, 1 and 2 mg/L), or 2,4-D
(0, 0.1, 0.5, 1 and 2 mg/L) plus TDZ (0, 1 and 2 mg/L). Subsequently, two types of somatic embryos were obtained
from callus cultures and named S-type and I-type embryos. The S-type embryos were obtained from an 18-monthold
callus line which was induced and maintained at 2 mg/L TDZ and 0.1 mg/L 2,4-D near the end of each period
of the subculture. These embryos have a developmental barrier, which did not pass through the torpedo stage
and could be overcome by a supplement of 2 or 5 mg/L BA. The I-type embryos were induced from 3-month-old
callus when transferred onto induction media, i.e., MS supplemented with TDZ (2 and 5 mg/L) plus 2,4-D (0 and
0.1 mg/L). The significantly highest response, i.e., 13.3 embryos per callus clump was obtained at 2 mg/L TDZ.
In this study, the results reveal that TDZ has a crucial effect on embryogenic callus induction, proliferation and
subsequent somatic embryogenesis.
Plant tissue culture techniques have become an integral part of progress in plant science research due to the opportunity offered for close study of detailed plant development with applications in food production through crop improvement, secondary metabolites production and conservation of species. Because the techniques involve growing plants under controlled conditions different from their natural outdoor environment, the plants need adjustments in physiology, anatomy and metabolism for successful in vitro propagation. Therefore, the protocol has to be optimized for a given species or genotype due to the variability in physiological and growth requirement. Developing the protocol is hampered by several physiological and developmental aberrations in the anatomy and physiology of the plantlets, attributed to in vitro culture conditions of high humidity, low light levels and hetero- or mixotrophic conditions. Some of the culture-induced anomalies become genetic, and the phenotype is inherited by clonal progenies while others are temporary and can be corrected at a later stage of protocol development through changes in anatomy, physiology and metabolism. The success of protocols relies on the transfer of plantlets to field conditions which has been achieved with many species through stages of acclimatization, while with others it remains a challenging task. This review discusses various adjustments in nutrition, physiology and anatomy of micro-propagated plants and field grown ones, as well as anomalies induced by the in vitro culture conditions.