The common potato, Solanum tuberosum L., is the fourth most important agricultural crop worldwide. Until recently, vegetative propagation by tubers has been the main method of potato cultivation. A shift of interest to sexual potato reproduction by true botanical seeds is due to the appearance of a new hybrid seed breeding strategy whose successful application for many crop species has been supported by male sterility. This investigation was focused on the study of differences in the metabolite profiles of anthers at the mature pollen stage from male-fertile and male-sterile genotypes of S. tuberosum. Application of gas chromatography coupled with a mass spectrometry method allowed detection of metabolic profiles for 192 compounds. Further data analysis with several libraries fully identified 75 metabolites; a similar amount was defined up to the classes. Metabolic profiles in the anthers of fertile genotypes were significantly distinguished from male-sterile ones by the accumulation of carbohydrates, while the anthers of sterile genotypes contained a higher amount of amino acids. In comparison with male-fertile plants, male-sterile genotypes had undeveloped pollen grain characters; i.e., smaller grain size, a thicker exine, “permanent tetrads” that failed to disintegrate into microspores, and the absence of pollen apertures that might be due to a disorder in the metabolism of carbohydrates and fatty acids.

Pollen of 62 species from the genus Euonymus (Celastraceae) were studied using light (LM), confocal laser scanning (CLSM) and scanning electron (SEM) microscopes. This is approximately half of the species composition of the taxon. The genus, as a whole family, is quite homogeneous by palynomorphological characteristics and represented by 3-colporate pollen type. On the other hand, some species and (or) group of species could be segregated considering the details of structure (aperture structures, exine ornamentation). We have found 3-colporate pollen in all investigated taxa and 19 species also have 2- and/or 4-6-deviated grains with different colpi arrangement. Their structure has been studied in more detail with a CLSM 3-dimentional reconstruction. Grains are isopolar, ellipsoidal or spheroidal medium sized, from 17 to 41 μm in diameter. Colpi are long, spired at the ends. Endoaperture (ora) range from poorly-defined, rounded or slightly elongared along the colpus up to well-defined, with sharp edges, elliptical and elongared along the equator. LM-observing shows H-shaped aperture; CLSM data demonstrate that they are constructed from ora bridge and exine thinning on both sides of parallel colpus. The exine is tectate, columellate, with well-defined columella layer. Exine thickness is from 1.5 to 5.1 μm. The ornamentation varies from reticulate to microperforate. The species groups divided according to their palynomorphological characteristics generally do not coincide with the genus subdivision onto subgenera and sections. The taxonomic significance of various palynologicalcharacteristics is discussed. С помощью светового (СМ), конфокального лазерного сканирующего (КСЛМ) и сканирующего электронного (СЭМ) микроскопов изучена пыльца 62 видов рода Euonymus (Celastraceae). Род, как и все семейство, довольно однороден по палиноморфологическим признакам и представлен трехбороздно-оровым типом пыльцевых зерен. Однако некоторые виды и (или) группы видов могут быть выделены с учетом деталей строения (апертур или поверхности экзины). У всех исследованных таксонов обнаружены 3-бороздно-оровые пыльцевые зерна, у 19 представителей наряду с 3-бороздно-оровыми встречаются также 2- и/или 4-6-бороздно-оровые зерна с разным расположением борозд и ор. Структура апертур изучена более подробно с использованием трехмерных реконструкций конфокальной микроскопии. Зерна радиально-симметричные, эллипсоидальные или сфероидальные, среднего размера, от 17 до 41 мкм в диаметре. Борозды длинные, заостренные на концах. Эндоапертуры (оры) встречаются от слабо очерченных, неясных, округлых или чуть вытянутых по борозде до хорошо различимых, с четкими краями, эллипсоидальных, вытянутых по экватору. Наблюдение с помощью СМ показывает H-образные апертуры, данные КЛСМ демонстрируют, что они состоят из оровой перемычки и утоньшений экзины с двух сторон параллельно бороздам. Экзина столбиковая, тектатная, в большинстве случаев хорошо выражен столбиковый слой. Толщина экзины от 15 до 5,1 мкм. Поверхностьварьирует от крупносетчатой до микроперфорированной. Выделенные по палиноморфологическим характеристикам группы видов в основном не совпадают с подразделениями рода на подроды и секции. Обсуждается таксономическое значение отдельных палинологических признаков.

Background.Learning about morphological and biological features of pollen is very important to make correct estimations of plant productivity and breeding efficiency.Materials and methods. The viability of black currant pollen was analyzed in 2019 at the Laboratory for Long-Term Storage of Plant Genetic Resources, N.I. Vavilov All-Russian Institute of Plant Genetic Resources (VIR). Eleven black currant cultivars of various ecogeographic and genetic origin maintained at Pushkin and Pavlovsk Laboratories of VIR served as the material for the research. Pollen viability was tested on an artificial medium with 10% sucrose and 0.8% agar. Morphological studies were carried out using light and confocal laser scanning microscopy at the Palynology Laboratory and the Core Centrum of Cell and Molecular Technologies in Plant Science housed by the Komarov Botanical Institute (BIN).Results and conclusion. The prevailing adverse weather conditions in 2019 produced a negative impact on the process of male generative structure formation. The level of pollen viability, depending on the cultivar, ranged from 17.98 to 58.60%. After exposure to liquid nitrogen (–196°C) for 6 months, the number of germinated pollen grains increased 1.1 to 3.2 times in all the studied cultivars, except one (‘Pozdnyaya poslevoennaya’, k-7652). A palynomorphological study revealed that reduced pollen viability in some cultivars (‘Krasnoyarskaya 1018’, k-7607; ‘Tsema’, k-25900; ‘Pozdnyaya poslevoennaya’, k-7652) was associated with morphological deviations in the sporoderm structure (small pollen grains, exine thickening and formation of verrucate mesoporium surfaces). A low positive correlation was observed between the level of pollen viability and the diameters of the pore (r = 0.43) and pollen grain (r = 0.27). An insignificant negative correlation was apparent between the level of viability and the exine thickness (r = –0.33).

Dispersed tricolpate pollen of Pseudointegricorpus clarireticulatum (Samoil.) Takah. from the Upper Maastrichtian in Zeya-Bureya Basin, Amur (Heilongjiang) River area, Russian Far East/China has been studied with light and electron microscopy. Pollen size, pole outlines and the shape of equatorial projections show some variation within the species. The exine is striate-reticulate, semitectate and columellate. The species is characterised by highly complex structures that have harmomegathic function and include equatorial projections, endexinous thickenings, difference in the thickness of the infratectum, foot layer and endexine throughout the pollen grain, and equatorial furrows. Exine layers taper towards colpi regions while they break abruptly in furrow regions. The furrows could have helped to shed the exine quickly and enabled pollen germination. A non-extended region with a small cavity in the ectexine was observed in the equatorial region. We think that this region is characteristic of most Triprojectate species.