Micromorphological differentiation of Korean Disporum species using light and scanning electron microscopy

Abstract

The genus Disporum Salisb. is widely distributed in East Asia, yet phylogenetically relevant morphological traits useful for differentiating many of the small, perennial, herbaceous species remain poorly described. To address this, leaf, floral, pollen, and orbicule micromorphology of four Korean Disporum species was investigated using light and scanning electron microscopy. All Korean Disporum species examined had hypostomatic leaves, with anomocytic stomatal complexes found only on the abaxial epidermis. Guard cell length varied among species, ranging from 44.30 μm in D. viridescens to 53.49 μm in D. uniflorum. The epidermal cells of the investigated Disporum taxa had sinuate anticlinal cell walls on both adaxial and abaxial surfaces. The surface of the guard and subsidiary cells were either smooth with weak striations or had strongly wrinkled striations. The pollen grains of all Korean Disporum taxa were monads, monosulcate with granular aperture membranes, subprolate to prolate in shape with microreticulate or verrucate exine surfaces. The mean size of pollen grains ranged from 46.38 to 49.92 μm in polar length and from 34.39 to 39.58 μm in equatorial diameter across species. Sexine ornamentation was a taxonomically relevant trait for differentiating Korean Disporum taxa. Additionally, the presence of orbicules as well as the orbicular characters (e.g., size, shape, ornamentation, and association pattern) are described for the first time in species from this genus. The present investigation of leaf and floral micromorphology using light and scanning electron microscopy provides valuable information for the taxonomic differentiation and identification of Disporum species in Korea. Research Highlights A detailed micromorphological description of leaf, floral characters (tepal, stigma, style), pollen and orbicule is provided for Korean Disporum species using scanning electron microscopy (SEM) and light microscopy (LM). The presence of orbicules and their taxonomic implications in Korean Disporum species are described for the first time. Phylogenetically informative pollen and orbicule micromorphological characters are described, improving understanding the systematic relationships of Korean species in the genus Disproum.

Implications of foliar epidermal micromorphology using light and scanning electron microscopy: A useful tool in taxonomy of Korean irises

“…The present study described the comparative micromorphological features of 15 Korean irises for the first time. The results of LM and SEM microscopic analysis revealed useful and reliable leaf micromorphological traits of economically important plant families (Choi, Kim, & Jang, 2020b; Gul et al, 2019; Kandemir et al, 2019; Kim et al, 2021; Klimko et al, 2018; Kong & Hong, 2019; Lima et al, 2020; Magauer et al, 2014; Tabaripour et al, 2022). The leaf characteristics of the investigated Korean irises showed great diversity in the leaf margin, epidermal cell outline, stomatal size, and the occurrence of abnormal stomata (Table 2).…”

“…All samples were analyzed by SEM at an accelerating voltage of 20 kV with a working distance of 10 mm. Detailed SEM examinations were carried out according to the methods described in Choi, Kim, and Jang (2020b) and Kim et al (2021).…”

Comparative analysis of two Korean irises (Iris ruthenica and I. uniflora, Iridaceae) based on plastome sequencing and micromorphology

“…Fresh leaf and flower materials from all four Iris populations were preserved using a formalin-acetic acid-alcohol solution and dehydrated by soaking in an acetone series (50, 70, and 90%) for 30 min and absolute acetone for 1 h. The dehydrated materials were then immersed in carbon dioxide for critical point drying (EMCPD300, Leica Microsystems, Germany), coated using an ion-sputtering device (E-1010, Hitachi, Japan), and analyzed using scanning electron microscopy (SEM; S3000N, Hitachi, Japan), with an accelerating voltage of 20 kV and working distance of 9–15 mm, following Choi et al 5 , as well as light microscopy (BX53F, Olympus, Japan), which was used to analyze the structure of leaf epidermal pavement cells and stomatal complexes, following Kim et al 7 . At least 20 guard cells were examined on both adaxial and abaxial leaf surfaces from each sample as described by Choi et al 5 .…”

“…Leaf, flower, and pollen micromorphology has been informative for resolving taxonomic problems in angiosperms across various taxonomic levels 1 – 7 . In particular, leaf epidermal stomata, orbicules, and pollen exine ornamentation characters have been shown to possess systematic values when examined using both light microscopy (LM) and scanning electron microscopy (SEM) and may further be utilized to test phylogenetic hypotheses 8 – 13 .…”

Leaf epidermal morphology of Asparagaceae of Taiwan and its systematic significance

“…The epidermal morphology of Asparagaceae showed high heterogeneity and without any consistent characteristic that could be separated from related families. Some taxa had similar epidermal morphology to another family; for example, Maianthemum had an undulate anticlinal wall and anomocytic subsidiary cell similar to those of Disporum species of Colchicaceae (Kim et al, 2021). Thus, the results of epidermal morphology provided weak support on the familial level.…”