Pollen ultrastructure in Aristolochia manshuriensis and A. contorta (Aristolochiaceae).

Pollen ultrastructure has been studied in two relict and rare species of the genus Aristolochia, A. contorta Bunge and A. manshuriensis Kom. (Aristolochiaceae). Both species have inaperturate, spheroidal, sometimes distally monocolpate or distally bicolpate pollen grains. The equatorial and polar axes of pollen grain in A. manshuriensis are 48.5 and 44.0 µm, respectively. The percentage of defective pollen grains in A. manshuriensis is 3.4%. The fossulate, perforated exine is up to 2.3 µm in thickness; the sexine and the nexine are almost equal in thickness. In A. contorta, the equatorial axis of pollen grain is 36.6 µm: the defectiveness percentage, 24.5%. The exine is verrucate, up to 0.3 µm in thickness, while the sexine is two to three times thicker than the nexine. The pollen germination experiments have shown that pollen of A. manshuriensis, in contrast to A. contorta, can germinate in 10-20% sucrose at 22°Ð¡. These data and the high percentage of pollen defectiveness in A. contorta indicate that the androecium function in this species is reduced. The reduction of the androecium function is evidenced by a small amount of pollen grains in anthers or empty anthers and a high percentage of defective pollen grains.

[Genetic variation of the relict species Acanthopanax sessiliflorus (Rupr. et Maxim.) Seem. (Araliaceae) in Primorsky Krai].

Based on the analysis of 17 genes encoding the allozyme diversity of 12 enzyme systems, data were obtained on the genetic variation of a relict of the Tertiary flora, a valuable medicinal plant Acanthopanax sessiliflorus (Rupr. et Maxim.) Seem. (Araliaceae) in the Russian area of its habitat. Indicators of polymorphism for populations had rather high values on average (P95 = 42.4%, A = 1.55, H(o) = 0.211, and H(e) = 0.168), which are comparable with the known data for populations of A. sessiliflorus from the peninsula of Korea. The level of genetic diversity and its distribution among populations reflects the interaction of several factors, among which the most important are the historical past of the species, genetic drift, and the plasticity of the reproduction system. The obtained data can serve as a basis for the conservation of genetic resources of Far Eastern Araliaceae species.