Pollen morphology of some selected species of the tribes Brassiceae, Conringieae, Isatideae, and Plagiolobeae (Brassicaceae) in Iran, and its taxonomic significance

Abstract

Pollen morphology of 12 species, representing genera of the tribes Brassiceae, Conringieae, Isatideae and Plagiolobeae were studied using light microscopy (LM) and scanning electron microscopy (SEM). The results demonstrated that the polar diameter, pollen exine ornamentation, mesocolpium width, and exine thickness have important systematic significance. Pollen grains in these genera were tricolpate and their shapes varied from prolate to perprolate, with the polar axis length ranging from 30.28 to 41.05 mm and the equatorial axis length ranging from 17.21 to 23.36 mm. However, fine details can be used to distinguish pollen grains of the different species within the genera. The exine ornamentation varied among genera within the tribes and among species within the same genus. Three pollen types are distinguished based on lumen size. All the studied tribes' pollen were heterogeneous, with reticulate, microreticulate (Conringia orientalis, Plagioloba derakii), or macroreticulate (Moricandia sinaica) ornamentation. The exine thickness ranged from 0.75 to 2.60 mm. Pollen characteristics support: (i) two distinct pollen types (viz. Conringia austriaca and Iljinskaea planisiliqua types) in all four tribes; (ii) the similarity of the pollen shape between tribes Isatideae and Brassiceae; (iii) the transfer of P. crenulata from Zuvanda to Plagioloba, and of I. planisiliqua from Conringia to Iljinskaea. Plagioloba clavata displays great variation in pollen morphological characters and needs to be further studied. A key to the species of the genera was also provided.

Pollen morphology of Matthiola and the related genus Dvorakia (Brassicaceae) in Iran

“…This research is particularly significant as nearly half of the taxa examined had never undergone palynological investigation before. This article follows previous palynological studies of Brassicaceae in Iran (Ranjbar and Karami 2023, 2022). This study aimed to survey the diversity of pollen morphology in the native species of Matthiola and its related genus Dvorakia , and to find useful pollen characteristics for the delimitation of their closely related species that may not be clear using morphological characters.…”

“…Some previous studies divided the pollen types of the Brassicaceae species based on the exine thickness, lumina size, and shape of the pollen (Erdtman 1963; Moore and Webb 1978; Abdel Khalik et al 2002; Perveen et al 2004; Ranjbar and Karami 2023, 2022). However, based on pollen size, four distinct pollen types are recognised here: viz.…”

“…The significance of pollen morphology in the systematics of Brassicaceae has been demonstrated in several studies. The exine ornamentation is an important feature in this family, differing among the genera within a tribe and among the species within a genus (Abdel Khalik et al 2002;Khan 2004;Pinar et al 2009;Franzke et al 2011;Fuentes-Soriano and Al-Shehbaz 2013;Ranjbar and Karami 2023). Brassicaceae is a stenopalynous family with pollen grains that are usually tricolpate and have reticulate ornamentation (Erdtman 1972;_ Inceo� glu and Karamustafa 1977;Rollins and Banerjee 1979;Erden and Menemen 2021;Ranjbar and Karami 2022).…”

“…It seems that a more comprehensive palynological survey of the family is needed to determine the utility of pollen in taxonomic and phylogenetic studies. Pollen data have been shown to be useful in the separation of putatively closely related genera (Rollins and Banerjee 1979; Karaismailoğlu and Erol 2019; Ranjbar and Karami 2023, 2022; this study).…”

“…Pollen morphology has provided a useful tool in circumscribing the genera of the Brassicaceae (Erdtman 1963; Sharma and Nair 1973; Carter et al 1975; Moore and Webb 1978; Jonsell 1986; Doğan and Inceoğlu 1990; Brochmann 1992; Reile 1992; Abdel Khalik et al 2002; Khan 2004; Perveen et al 2004; Pinar et al 2009; Keshavarzi et al 2012; Mutlu and Erik 2012; Sagun and Auer 2017; Başer et al 2018; Ranjbar and Karami 2023, 2022) and a wealth of information has been published on the phylogeny of the Brassicaceae (Al-Shehbaz et al 2006; Beilstein et al 2006; German et al 2009; Khosravi et al 2009; Couvreur et al 2010; Warwick et al 2010; Zhao et al 2010; Hendriks et al 2022). Mostly, Brassicaceae have only tricolpate pollen (Erdtman 1972), but preliminary surveys (e.g.…”