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.

We have tested possibilities and limitations of confocal laser scanning microscopy to study the morphology of pollen and spores and inner structure of sporoderms. As test objects, we used pollen grains of the modern angiosperm Ribes niveum (Grossulariaceae) and Datura metel (Solanaceae), fossil angiosperm pollen grains of Pseudointegricorpus clarireticulatum and Wodehouseia spinata dated to the Late Cretaceous, fossil gymnosperm pollen grains of Cycadopites-type dated to the Middle Jurassic, and fossil megaspores Maexisporites rugulaeferus, M. grosstriletus, and Trileites sp. dated to the Early Triassic. For comparative purpose, we studied the same objects with application of conventional light, scanning electron (to entire pollen grains and spores or to semithin sections of their walls), or transmission electron microscopy. The resolution of confocal microscope is much lower than that of electron microscopes, as are its abilities to reconstruct the surface patterns and inner structure. On the other hand, it can provide information that is unreachable by other microscopical methods. Thus, the structure of endoapertures in angiosperm pollen grains can be directly observed. It is also helpful in studies of asymmetrical pollen and pollen grains bearing various appendages and having complicated exine structure, because rotation of 3-D reconstructions allows one to examine all sides and structures of the pollen grain. The exact location of all visible and concealed structures in the sporoderm can be detected; this information helps to describe the morphology and inner structure of pollen grains and to choose necessary directions of further ultrathin sectioning for a transmission electron microscopical study. In studies of fossil pollen grains that are preserved in clumps and stuck to cuticles, confocal microscope is useful in determining the number of apertures in individual pollen grains. This can be done by means of virtual sections through 3-D reconstructions of pollen grains. Fossil megaspores are too large and too thick-walled objects for a confocal study; however, confocal microscope was able to reveal a degree of compression of fossil megaspores, the presence of a cavity between the outer and inner sporoderm layers, and to get some information about sporoderm inner structure.

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