Vol 108, No 10 (2023)

The present review outlines the history of the study of plasmodesmata in brown algae, describes their ultrastructure, which differs from that of other groups of algae and land plants, presents variants of localization of plasmodesmata in different members of Phaeophyceae – from a scattered location to arrangement into pit fields; the functions performed by plasmodesmata in the thalli of brown algae are listed. Possible prospects for further study of these structures are specified.

The ability of the zygotes and seedlings of the green alga Ulva lactuca to develop under the influence of crude oil in various concentrations was determined. The oil at a content of 1 mg/l in water does not have a damaging effect on the germination of zygotes and their further development into multicellular seedlings. Juvenile seedlings have a wider tolerance range than zygotes and can develop under oil content in marine water up to 3 mg/l. The real threat of the death of zygotes, which rovide replenishment of ulva algae thickets in the littoral with young thalli, is observed under short-term oil pollution of more than 25 mg/l, or with constant oil pollution of more than 5 mg/l. The oil content in water of  25 mg/l and above stops the development of most seedlings by irreversibe destroying the structure of their cells.

The relationship of the chemical composition of plants with conditions of their growth and their contribution to soil nitrogen during dying is revealed. The study was based on the materials of geobotanical relevés of 15 forest plots in the subzone of coniferous-deciduous forests in the south of the Moscow Region. Two methods of phytoindication were used. The type of habitat conditions was determined according to the Vorobyov-Pogrebnyak’s indicator species. The point values of soil nitrogen richness were calculated according to the Tsyganov’s scale. The nitrogen content in plant organs, samples of forest litter and soil was determined using gas chromatography. The analysis of the data showed a correlation between the types of forest vegetation conditions and the points on the Tsyganov’s nitrogen richness scale for the conditions of the southern Moscow Region. The nitrogen content in the forest litter has a high reliable relationship with the types of habitat conditions. It is shown that plants from the habitats which are richer in nitrogen according to the Tsyganov’s nitrogen richness scale have a higher nitrogen content in leaves, stems and rhizomes than plants growing in poorer soil conditions. The conducted study has shown the validity of using phytoindication scales for the assessment of soil conditions.

The article provides information on the discovery of a new alien species to the flora of the Khabarovsk Territory, Potentilla tobolensis Th. Wolf ex Juz. The species was previously known as alien from the Primorie Territory and Eastern Europe. The presented information about Potentilla tobolensis will make the basis for monitoring its distribution in the Khabarovsk Territory.

There are many investigations concerning material processing and staining of permanent or temporal mounts for light microscopy, and there are many works on Helianthus embryology either with the description of the methods or without it. Our aim was to make a review of these methods and to customize existing methods of permanent and temporal mounts staining for the work with representatives of the genus Helianthus to get good quality photo images.

Wild perennial species Helianthus ciliaris, H. tuberosus, H. maximilianii, as well as cultivated forms of annual sunflower H. annuus were included in our research. The most of methods were worked out on H. ciliaris, and then were successfully used in the work with other Helianthus species listed above.

When following classical methods, some stains become very pale or wash out completely during processing of the sunflower mounts. We developed some practices to avoid these failures. They are: prolongation of stains exposure; staining at higher temperature; reducing the time of processing by ethanol, acetic acid and other substances that can wash out the stain; changing the order of stains exposure; changing the way of mounts dehydration (drying in thermostat instead of treatment by absolute ethanol).

We found out optimal techniques for staining of male and female reproductive structures of sunflower and the methods suitable for all structures: toluidine blue, Schiff’s reactive with alcian or toluidine blue as counter-stains, safranin with alcian blue. It is convenient to use acetocarmine solution for the estimation of sunflower pollen viability.

Chloral hydrate, methyl benzoate or “Bio Clear” solution are applicable reagents for clearing ovules. The material after chloral hydrate or methyl benzoate is satisfactory to embed in paraffin and to make permanent mounts.

The All-Russian scientific conference “Study and conservation of biodiversity of ecosystems of European Russia” dedicated to the 150^th anniversary of Doctor of Biological Sciences, Professor I.I. Sprygin and the 40^th anniversary of the Institute of Ecology of the Volga Basin of the Russian Academy of Sciences was held from July 4 to July 7, 2023, at the Institute of Ecology of the Volga Basin of RAS (Tolyatti). 55 scientists (32 of them from other cities) from 20 scientific institutions of Russia took part in the Conference in person.