Starch is a biologically and commercially important polymer of glucose.1 3) It is synthesized to form starch grains (SGs) inside amyloplasts of higher plants. Because starch is clearly stained by iodine solution, the subcellular morphologies of SGs can be easily observed under the microscope. 4)Despite the simple composition of glucose polymers, SGs exhibit various morphologies depending on plant species. 12)Morphologically, SGs are classified as either compound or simple grains. Compound grains consist of many starch granules in a single amyloplast, and simple grains are composed of a single starch granule in an amyloplast. The endosperm of Poaceae species accumulates high levels of starch up to more than 90% of total weight. Previously published work classified Poaceae species into four types based on the SG morphologies of endosperms. 8,13) Species that have a compound grain type such as rice (Oryza sativa) possess only compound grains in their endosperms. Species that have a simple grain type are further divided into two subtypes referred to as bimodal and uniform. The bimodal type produces both small and much larger simple SGs that coexist in the same cells. The uniform type possesses similarly sized hexagonal, pentagonal, round and simple SGs. For example, barley (Hordeum vulgare) and wheat (Triticum aestivum) develop bimodal SGs, and uniform SGs are found in maize (Zea mays). In the fourth type of SG morphology, a number of species of Miscanthus, Perotis, Gymnopogon and Thuarea display a mixed configuration of compound and simple grains inside the same cell of the endosperm. 8)Despite the comprehensive observations of SG morphologies in planta, a detailed examination of the phylogenetic origin of the morphological diversities of SGs is lacking. It is not known which SG morphological type is plesiomorphic in the family Poaceae, or how SG morphological types are clustered and scattered in the phylogenetic tree. In this study, we evaluated the previous observations of SG morphologies in the Poaceae and arranged these data on the most current phylogenetic tree of the Poaceae. Furthermore, we prepared thin sections of endosperms and observed SG morphologies of 26 species belonging to the four genera Hordeum, Elymus, Triticum and Bromus, which were found to be clustering in the phylogenetic tree. In previous work, these four genera were considered to exclusively contain the bimodal simple grain type. However, this study showed that Bromus species contained remarkable intrageneric variation. This result contrasted with data for the other three genera, which contained only bimodal simple grains. The phylogenetic analysis performed in this study will lead to a greater Abstract: Starch forms transparent grains, referred to as starch grains (SGs), in amyloplasts. Despite the simple glucose polymer composition of starch, SGs exhibit different morphologies depending on plant species, especially in the endosperm of the family Poaceae. In previous comprehensive work, SG morphologies of Poaceae endosperm were classified...
ABSTRACT. Karyomorphology of four species and one variety of Japanese Mosla were observed. They had commonly chromosomal characters at resting nuclei of the complex chromocenter type, and the mitotic metaphase cells showed 2n=36 for M. japonica, 2n=18 for M. chinenis, M. scabra, M. dianthera and M. dianthera var. nana. The chromosome numbers of 2n=18 and 36 were considered diploid and tetraploid, respectively if the basic number x=9 was accepted. The chromosome number of 2n=18 for M. dianthera var. nana was reported here for the first time, and that of the other four species were verified with the previous reports. The karyotypes of five taxa had commonly similar karyomorphology to each other except for chromosome numbers; small sized chromosomes (2.2 to 1.1 µm long), mono-modal (gradual) decrease in chromosome length from the longest to the shortest chromosomes, and consists of median-and submedian-centromeric chromosomes. The genus Mosla Buch.-Ham. ex Maxim. is one of the three genera in the subtribe Perillinae Briq., the family Lamiaceae (Labiatae), consists of about 22 species (Wu and Li 1977b;Li and Hedge 1994), that are commonly annual herbs and aromatic plants, and grow in grassy slopes, forest margins, hills thickets, open hills and stream-sides in temperate regions of India, Southeast Asia and East Asia. Among the species of this genus, 12 species are found in China (Li and Hedge 1994) and four species and one variety grow in Japan (Murata and Yamazaki 1993). KEYWORDS:Seven species (including a synonym) of Mosla have been cytologically studied previously and documented their chromosome numbers as n=9, 2n=18 and 2n=36 (e.g., Sugiura 1931;Suzuka 1953;Mehra and Gill 1968;Gill 1971Gill , 1984Probatova and Sokolovskaya 1986;Sokolovskaya et al. 1986;Zhang and Xu 1988;Hsieh and Huang 1999), and these studies are only chromosome numbers reports. This paper reports detailed karyomorpholoies (the resting nucleus and the mitotic metaphase chromosomes) in the Japanese species of Mosla. MATERIALS AND METHODSSixty-nine plants of four species and one variety of Mosla were collected in 14 localities in Japan ( Fig. 1; Table 1), and cultivated in unglazed plant-pots in shade place in the experimental garden of Showa Pharmaceutical University. Chromosome observations were made in meristematic cells of fresh root tips. They were cut off 5-10 mm long and pretreated in 2 mM 8-hydroxyquinoline at ca 20ºC for 4 h and then fixed in 45% acetic acid at ca 2ºC for 10 min. They were macerated in a mixture of 45% acetic acid and 1N hydrochloric acid (1:1) at ca 60ºC for 20-23 sec and were then stained with 2% aceto-orcein at room temperature in moist chamber with 45% acetic acid for ca 30 min and were prepared by the conventional squash method. The slides were faintly heated under an alcohol frame for 1-2 sec before observation. Measurements of chromosome length were made in each average length in several good metaphase cells.Morphological type of the resting nuclei was classified for Tanaka (1971, 1977), and classifications of mit...
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.