Description of seed and pollen micromorphology and their taxonomic impact in some Solanum L. species

Document Type : Original Article

Authors

1 Botany and microbiology department, Faculty of Science, Helwan University, Helwan

2 Botany and microbiology department, Faculty of Science, Cairo University, Cairo

3 Faculty of Science, Helwan University

4 Botany Department, Faculty of Science, Tanta University, 31529 Tanta, Egypt

Abstract

Seed micromorphology, of 17 species and pollen micromorphology of 16 species of Solanum L. (Solanaceae) were examined using both light and scanning electron microscopy (SEM) to determine the significance of seed coat features and pollen characteristics as taxonomic characters. The species, used in this study, represent three subgenera and 11 sections of Solanum in Egypt. Macro and micro-morphological characters including seed shape, size, colour, surface; hilum shape, size, position, level; seed coat appearance, cell wall; shape of pollen in polar and equatrorial view, colpus membrane and apices and exine ornamentation have been described and their taxonomic impacts have been outlined. Seed shape was either obovate or reniform and seed size ranged between 1.1and 3.8 mm in length and 0.9 to 3.1 mm in diameter. Four types of seed coat appearance have been described: reticulate, cerebelloid, striate and without conspicuous cell lumen and six types of pollen shape were found in the studied species: prolate, subprolate, spherical, prolate-spheroidal, oblate-spheroidal and perprolate. Pollen length in polar view ranged from 15 µ to 34 µ but in the equatorial view it ranged from 9.1 µ to 25 µ. Four types of exine ornamentation have been recognized: scabrate, psilate, granulate and verrucate. Nineteen characters of seed and pollen micromorphology features proved useful in the construction of a dichotomus indented systematic key for the examined species. The major remarks are the differentiation of S. melongena, S. schimperianum, S. forsskaolii and diphyllum by their reinform seed shape from the remaining species which have ovoid seed shape. Hairy seed surface distinguishes Solanum lycopersicum, S. seaforthianum, S. nigrum and S. vilosum. Seed coat colour, appearance and pollen shape were useful traits for the identification of other nine species.

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