Palyno-Morphological Characteristics as a Systematic Approach in the Identification of Halophytic Poaceae Species from a Saline Environment

Abstract

Pollen morphology of 12 salt-tolerant grasses (Calamagrostis pseudophragmites, Cenchrus biflorus, Cenchrus ciliaris, Cenchrus pennisetiformis, Cymbopogon jwarancusa, Dactyloctenium aegyptium, Echinochloa colona, Echinochloa crus-galli, Saccharum griffithii, Saccharum ravennae, Saccharum spontaneum, and Urochloa ramosa) from the Salt Range was studied using scanning electron microscopy (SEM) and light microscopy (LM). The main aim was the elucidation of taxonomic significance of pollen morphology, which might be useful for taxonomists in the identification of halophytic Poaceae taxa. The described pollen morphology is a good source of taxonomic characteristics that can help in species and genera differentiation. The investigated variations in the pollen micromorphological features and exploration of new palynological traits support and strengthen the systematics of Poaceae. The pollen shape of all studied species was sub-spheroidal, and exine ornamentation includes microechinate-areolate (11 spp.) and microechinate (1 spp.). Two types of pollen apertures were reported, i.e., monoporate (11 spp.) and diporate (Cenchrus pennisetiformis). The annulus was found in all species while operculum was observed only in three species. The univariate and multivariate analyses were used to analyze the quantitative data. The highest pollen viability values (%) depicted the adaptability of Poaceae taxa in the salt region. Overall, the pollen characteristics in polar and equatorial view, apertures, annulus, operculum, and surface ornamentation of pollen grains of the family Poaceae are of great taxonomic significance for the species identification.

Pollen Grains and Caryopsis Features of Selected Poaceae species and Their Taxonomic Significance

“…The pollen grains of studied species have oblatespheroidal, spheroidal and prolate-spheroidal shape, prolate-spheroidal is the dominant shape for the studied species while four species appeared oblate-spheroidal and three appeared shape spheroidal, this is in agreement with [20]. The aperture for pollen grains of the studied species are monoporate or diporate with distinct or reduced annulus, which agree with [19,22]. Exine ornamentation is an important feature from an evolutionary and phylogenetic point of view [54].…”

“…However, palynology does not correspond with tribal and generic classification, it is significantly helpful at the specific level. Pollen morphology of the family Poaceae were examined by using different apparatus as LM, SEM and TEM by many scientists as [14][15][16][17][18][19][20][21][22].…”

Exploration of salinity effect on palyno-morphological characteristics of plant species collected from salt range

“…The highest pollen viability values (%) elucidates the adaptation of studied plant species in the Salt Range. Nazish and Althobaiti (2022) also reported Echinochloa crus-galli with high pollen viability value in Salt Range. The role of palynological study in plant taxonomy has evidenced valuable in solving disputed and critical taxonomic issues, therefore, the studied palynological features in the current study would be more useful for further karyological and taxonomic evaluation of salt-tolerant floral diversity.…”

“…The biometry and pollen morphology of 17 Amaranthaceae taxa have been examined by Angelini et al (2014) They reported perforations and echinae on radially symmetrical and spheroidal pollens. Nazish and Althobaiti (2022) studied pollen morphology of Poaceae species from Salt Range using LM and SEM and reported annulus and monoporate pollen apertures in most of the species. The grass distribution in any region depends on the soil chemical and physical nature.…”

Modifying the Expression of Cysteine Protease Gene PCP Affects Pollen Development, Germination and Plant Drought Tolerance in Maize

“…Our study revealed that the surface morphology of OE pollen grains was smoother than that of KO and WT grains, which may affect pollen–stigma interaction and further pollen germination. Operculum is commonly observed in Gramineae pollen grains that all have ulcerate apertures [ 28 , 34 ]. It is an exine thickening that covers most of the aperture, especially in wind-pollinated maize.…”