Micromorphological and cytological comparisons between Youngia japonica and Youngia longiflora using light and scanning electron microscopy

Abstract

The genus Youngia Cass. is taxonomically complex and widely distributed in East Asia. Despite the high diversity of species, only two species, Youngia japonica (L.) DC. and Youngia longiflora (Babc. & Stebbins) C.Shih, are currently found in Korea. Among them, Y. longiflora was once recognized as a subspecies of Y. japonica. However, based on chloroplast and nuclear DNA sequences, as well as morphology, Y. longiflora was found to be a distinct species. Here, the two Korean Youngia species were analyzed using scanning electron microscope and light microscope for chromosome number, pollen, cypselae, and leaf micromorphological characters to evaluate if the examined characters are informative for taxonomy. Pollen morphology is described, and the micromorphological characters of Y. longiflora are described for the first time. Cypselae and pollen surface ornamentation, as well as trichome morphology and stomatal size varied between the two species. Y. japonica had longer chromosomes than Y. longiflora, while other chromosomal characters including the localization of the NOR (nucleolar organizer region) were similar. The present micromorphological and cytological results are of great taxonomic value for Youngia species identification in Korea.

Youngia hangii (Asteraceae, Crepidinae), a new species from Hubei, China

“… japonica subsp. japonica , which is supported by micromorphological and cytological evidence ( Choi et al 2020 ). Youngia nansiensis Y.Z.…”

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

“…Thus, pollen size and shape are often not considered as traits of systematic significance (Hu, Zhao, Zhao, & Liu, 2020). In contrast, the surface ornamentation of pollen grains is generally accepted as an informative character for species level differentiation, regardless of sample preparation method (Carrijo et al, 2013; Choi, Kim, & Jang, 2020; Tuler et al, 2017; Xiong et al, 2019). In this study, the sexine ornamentation of the studied taxa was taxonomically informative, and categorized as microreticulate and verrucate (Table 3).…”

“…Leaf epidermal characteristics were observed in fragments (1–2 cm 2 ) from the middle portion of each selected mature leaf as described in Choi, Kim, and Jang (2020). At least two specimens for each taxon were prepared.…”

“…The micromorphology of leaf and floral indumentum as well as pollen exine ornamentation are traits widely utilized by plant systematists because they may provide important diagnostic characters for the differentiation of plant groups at different taxonomic levels (Choi, Kim, & Jang, 2020; Gul et al, 2019; Jang, Lee, & Hong, 2014; Klimko, Nowińska, Wilkin, & Wiland‐Szymańska, 2018; Kong & Hong, 2019; Magauer, Schönswetter, Jang, & Frajman, 2014; Moon, Hong, Smets, & Huysmans, 2009; Park, Yang, Song, & Moon, 2020). Despite the taxonomic importance of micromorphological characters in the family Colchicaceae (Bahadur et al, 2019; Membrives, Pedrola‐Monfort, & Caujapé‐Castells, 2003; Tomaszewski & Zieliński, 2014), only a limited number of micromorphological studies have been conducted in the genus Disporum (Chao & Tseng, 2019; Lee, 1979; Lee & Yeau, 1990; Wang, Gu, Zhao, & Liu, 2018).…”

Genome Size and Chromosome Number Evolution in Korean Iris L. Species (Iridaceae Juss.)

“…Subsequently, to perform Feulgen staining, the root tips were treated in Schiff′s reagent (Merck KGaA, Darmstadt, Germany) in darkness for 1 h. Microscopic slides were prepared by squashing the meristematic tissue in 60% acetic acid. A minimum of three well spread chromosome plates were selected for the analyses [ 32 ]. The chromosomes were cut using Corel Photo-Paint 12.0 (Corel Company, Ottawa, Canada).…”