Morphology of pollens has attained the attention of scientist and it refers to investigate size, structure and shape of pollen grains. Researchers specifically taxonomists are focusing on pollen morphology which is playing a crucial role in solving some taxonomic issues regarding family, generic or specific level. This field has become part of the multidisciplinary and collaborative approach in classification and evolution of palnts1. Brown has the distinction to investigate the significance of the morphological characters of pollen grains in classification of plants for the first time2.
Researchers are performing experiments on Brassicaceae (Cruciferae); which is one of the chief angiosperm families comprising about 350 genera and about 3660 species3. Chaudhary mentioned 74 species of Brassicaceae belonging to 53 genera in Saudi Arabia4. While, 46 species and 30 genera of this exclusive family; are present in the eastern region of Saudi Arabia5. Examining pollen morphology of Brassicaceae has paved a way to classify among genera and species more authentically6,7. Many researchers have investigated the morphological characters of pollen grains for species and taxa of Brassicaceae growing in Saudi Arabia as well as other territories11.
Dalia Goda Ibrahim Gabr conducted a study to examine the pollen grains of some species of Brassicaceae growing in eastern region of Saudi Arabia. Light microscope (LM) and scanning electron microscope (SEM) were used to inspect the pollen morphology of 10 species belongs to 9 genera and five tribes of Brassicaceae. For the SEM; the pollen was placed directly on brass stubs without treatment and mounted onto a metallic stub with a double-sided adhesive tape. Gold coating of few nanometers was implemented; using sputter coating machine (Quorum, Q150R ES, UK) to shun charging and capture high quality images. In this experiment, two statistical program; PRIMER 6, version 6.1.6 and SPSS version 16 were utilized to explore the associations among species under examination.
Three types of shapes of pollen grains were observed in this experiment; prolate, subprolate and prolate-spheroidal and prolate was the main one. In all 10 species; the apertures were tricolpate and two types were exhibited following exine ornamentation; reticulate and coarsely reticulate. Numerical analysis presented that species were grouped into two major clusters and each cluster divided into two groups.
Accordingly, it can be concluded that the pollen morphology can be used for identification and differentiate between the species belong to the same genera. Conversely, taxonomical classification for the different tribes can’t be done with the help of this meticulous character.
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17 November, 2019