Pollen tube branching in the ovary of five species of Oenothera

Flowers of Oenothera hookeri Torr. et Gray, Oe. brevistylis and Oe. lamarkiana de Vries were pollinated after anthesis by insects. Oe. biennis L., Oe. suaveolens Desf and sulfurea were selfpollinated in the buds. Pollen morphology was slightly different: Oe. hookeri have regular, triporated pollen, often germinating through two pores; in Oe. suaveolens many pollen grains had callose patches on the intine; in Oe. brevistylis tetraporated pollen were more often than in other species; in Oe. lamarckiana many pollen grains were empty; in Oe. biennis and Oe. suaveolens pollen grain size and viability varied. The pollen tube growth and fertilization were similar in 5 species and can be considered as typical for Oenothera. In the ovary pollen tubes branched and changed their growth direction. Near micropyle they formed short branches to the inner integument. In the nucellus the pollen tube became swollen

The ovule as an active partner in sexual reproduction of flowering plants

The fertility of flowering plants depends on correct course of the progamic phase (time from pollination to the pollen tube penetration into the ovule) and successful fertilization. Intercellular interactions are very important for the effective pollen tube growth in the pistil tissues. The ovule, which interacts with the male gametophyte in the final stage of progamic phase, is an active partner, attracting and supporting the pollen tube growth. To play its key role in fertilization the ovule undergoes a specific maturation process, especially on itsmicropylar pole. Inmicropyle of the receptive ovule there are extensive intercellular spaces, filled with extracellular matrix substances important for pollen tube growth. There are present specific glycoproteins (e.g. arabinogalactan proteins - AGP), esterified pectins, and deesterified pectins, which bind calcium ions. Functions of these substances for supporting and attracting the pollen tube growth are discussed

Pollen tube incompatibility reaction on the stigma in selfpollinated Sinapis alba L.

After selfpollination of Sinapis alba L. pollen tubes growth is inhibited on the stigma. The pollen grains germinate 3-4 hours after pollination. The pollen give rise to one or more pollen tubes. They grow along the papillae. In the place of contact between the papilla and pollen tube the pellicula is digested. Then the direction of pollen tube growth changes completely. Pollen tubes grow back on the exine of their own pollen grain, or turn into the air. The pollen tubes growth was inhibited in 6-8 hours after selfpollination. After crosspollination usually there is no incompatibility reaction

The phenolic acids of some species of the Oenothera L. genus

The occurence and approximative quantitative proportions of the phenolic acids in four species of the Oenothera L. genus was determined by the method of TLC and HPLC. In all species of Oenothera L. genus the permanent occurrence of acids: 2-hydroxy-4-metoxybenzoic, salicylic, ferulic, syringic, vanillic, p-coumaric, p-hydroxybenzoic, p-hydroxyphenylacetic, γ-rezorcil, gentysic, protocatechuic, caffeic and gallic has been confirmed. Whereas the other phenolic acids: o-coumaric, o-hydroxyphenylacetic and pirocatechuic were found in some species of the Oenothera L. genus only