Pollen morphology and its taxonomic potential in some selected taxa of Caesalpiniaceae observed under light microscopy and scanning electron microscopy

Farhat Ullah; Mushtaq Ahmad; Muhammad Zafar; Bushra Parveen; Shomaila Ashfaq; Saraj Bahadur; Qura-Tul-Ain Safdar; Luqman Bin Safdar; Fakhre Alam; Muhammad Luqman

doi:10.1002/jemt.24004

Pollen morphology and its taxonomic potential in some selected taxa of Caesalpiniaceae observed under light microscopy and scanning electron microscopy

Microsc Res Tech. 2022 Apr;85(4):1410-1420. doi: 10.1002/jemt.24004. Epub 2021 Nov 30.

Authors

Affiliations

¹ Department of Plant Sciences, Quaid-i-Azam University, Islamabad, Pakistan.
² Department of Botany, Rawalpindi Women University, Rawalpindi, Pakistan.
³ College of Forestry, Hainan University, Haikou, China.
⁴ Government Associate College for women, Faisalabad, Pakistan.
⁵ School of Biosciences, University of Nottingham, Nottingham, UK.
⁶ School of Agriculture, Food and Wine, Waite Research Institute, The University of Adelaide, Adelaide, South Australia, Australia.

PMID: 34850481
DOI: 10.1002/jemt.24004

Abstract

Pollen micromorphology is not only used to check the functional and structural evolution in plants but also to solve the taxonomic problem related to the classification of plants. Therefore, keeping in view the significance of pollen traits, selected taxa of the subfamily Caesalpiniaceae was collected from different geographical regions of Pakistan. The species were then analyzed under both light microscopy and scanning electron microscopy techniques to investigate the importance of micromorphological characters of pollen in the identification and classification of species. Great variation was recorded in equatorial shape, surface ornamentation, tectum, polar diameter, equatorial diameter, and exine thickness. However, little variation was observed in pollen type, polar shape, and fertility of pollen. The equatorial shape of five types was observed: prolate, prolate-spheroidal, spheroidal-subprolate, subspheroidal-prolate, and subspheroidal. Four types of surface ornamentation, psilate, granulate, clavate, and perforate, were recorded. Tectum of five types, intactate, reticulate regulate, medium reticulate, tactate, and striate, was observed. Sexine was thicker than nexine in all studied species. The largest polar diameter was observed in Caesalpinia pulcherrima 64.1 μm while the smallest in Parkinsonia aculeata 26.1 μm. The largest equatorial diameter was found in C. pulcherrima of 70.25 μm whereas the smallest in P. aculeata 27.57 μm. All the pollens analyzed were tricolporate. All studied species have a fertility ratio of more than 90%. A taxonomic key was developed to show the variation in pollen features and delimit species for the correct identification. In conclusion, the pollen traits were found useful to define species boundaries at various taxonomic ranks and will strengthen the taxonomy of this subfamily. Besides, this study also explored the palynological traits and their implication in the taxonomy of the subfamily Caesalpiniaceae.

Keywords: Caesalpiniaceae taxa; light microscopy and scanning microscopy; pollen micromorphology; taxonomic significance.

MeSH terms

Caesalpinia*
Microscopy, Electron, Scanning
Pakistan
Pollen* / anatomy & histology

Grants and funding

University of Peshawar