Diversity of Sambucus nigra pollen within Slovakia in selected morphological characters by SEM study

O. Grygorieva,V. Horčinová Sedláčková,O. Vergun,I. Gurnenko

doi:10.15421/012051

Abstract

This study analyzed pollen morphology and characteristics of 20 Sambucus nigra L. genotypes from populations of various ecotypes and geographical localities from the territory of Slovakia. We used principal component analysis to explore variability in pollen grain size (polar and equatorial diameter), shape, aperture type, and exine ornamentation by scanning electron microscopy. The combination of these morphological characteristics and ultrastructure allows us to determine the differences or similarities between the same and various species and genotypes, which may be a useful tool for systematics with significant diagnostic value. The findings confirmed small differences among the genotypes in measured traits with polar and equatorial diameters in the range from 22.30 to 26.64 μm and from 12.81 to 14.45 μm, respectively. Shape index (P/E ratio) depending on elongation or roundness of pollen grains varied from 1.66 to 2.02. Hierarchical cluster analysis (HCA) and principal component analysis (PCA) of morphological data helped to compare evaluated morphometric parameters and identified three closely related groups. It was noted that the diversity of surface sculpturing of pollen grains in combination with their shape and size enables us to use a complex of fine morphologic signs for S. nigra pollen identification. Pollen data combined with other morphological evidence (e.g., floral characters) have more recently become an important indicator of which genotypes may be the best representatives of species.

Highlights

Carl Nilsson Linnæus first used the term pollen
Pollen shape refers to the 3-dimensional form of a pollen grain concerning the proximal/equatorial ratio (P/E) ratio
Results of 20 tested genotypes of S. nigra pollen morphology were calculated for the polar (p.a.) and equatorial axis (e.a.), which showed that dry pollen grains are generally from small (10–25 μm) to medium size type (25–50 μm), in accordance with dimensions and P/E ratio (Fig. 2) pollen grains are frame in prolate type

Summary

Introduction

Carl Nilsson Linnæus first used the term pollen. In the 18th and the early 19th centuries, there was considerable progress in pollen research and the understanding of pollination. The transfer of male gametic material by insects classified the genus Sambucus as entomophilous (Farré-Armengol et al, 2015) It is associated with pollen production, which involves incomparably lower investments in male flowers, but they generally have higher investments in the production of rewards and signals for attracting pollinators (Candolle & Sprengel, 1821; Friedman & Barrett, 2009). Pollen grains adapted to different strategies have anatomical-morphological differences These male haploid organisms usually have as variable parameters: the pollen shape and size, the number, type, and position of apertures, and the pollen wall with its extremely diverse structure and sculpture. The use of pollen morphology as a taxonomic character is challenging, and pollen characteristics must be considered in concert with other characteristics in evolutionary reconstructions

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Discussion

Conclusion