Epidermal features and spikelet micromorphology in Oryza and related genera (Poaceae: Oryzeae)

Abstract

Features and Spikelet Micromorphology in Oryza and Related Genera (Poaceae: Oryzeae). Smithsonian Contributions to Botany, number 91, 50 pages, 33 figures, 3 tables, appendix, 2001.-Using scanning electron microscopy, this study examines the spikelet morphology of sixteen species of Oryza, one species of Leersia, and one species each of the monotypic genera Porteresia and Rhynchoryza. A detailed discussion of the spikelet epidermal features and their relationship to the pedicel and cupule is presented. As the pedicel and cupule of species of Oryza are below the point of articulation of the spikelet, have similar epidermal features, and are free from the vascular cylinder that proceeds upward (distally) into the spikelet, we conclude that the pedicel cupules are not glumes but are merely expanded apices of the pedicels. An original data set of 14 morphological characters was used to perform parsimony and UPGMA analyses. Of these 14 characters, six describe the lemma, three describe the rachilla, two describe the glumes, two describe the articulation point and callus shape, and one describes the embryo. Our classification of Oryza recognizes three subgenera: Oryza subg. Oryza; 0. The rice genus, Oryza, comprises approximately 22 species distributed in Asia, Africa, Australia, and the Americas. Using scanning electron microscopy this study examines the spikelet morphology of sixteen species of Oryza, one species of Leersia, and one species each of the monotypic genera Porteresia and Rhynchoryza. Previous studies have discussed the morphology and anatomy of the spikelets of Oryza (von Hohnel, 1875;Van Breda de Haan, 191 1; Akemine, 1913;Graham, 1913;Weatherwax, 1929; Roschevitz, 1931;Santos, 1933;Juliano and Aldama, 1937;Jacques-Felix, 1955;Tateoka, 1962a Tateoka, , 1962bTateoka, , 1963 Tateoka, , 1964 Tateoka, , 1965a Tateoka, , 1965bTateoka and Pancho, 1963;Chang and Bardenas, 1965;Nunez, 1968;Roy, 1968;Katayama, 1969). Other papers employed scanning electron microscopy to illustrate parts of the rice spikelet (e.g., Maeda, 1972;Soni and Parry, 1973;Hoagland and Paul, 1978; Zee, 1981) or to describe silica localization in the spikelet tissues (Locci and Quaroni, 1975;Yoshida et al., 1962; Garrity et al., 1984). A previous study (Terrell et al., 1983) Universiv, DeKalb. Illinois, 6011.5-2861; S.A. Renvoize, Herbarium, Royal Botanic Gardens, Kew, Richmond, Surrey TW9 2AE. U. K. D.C. 20.560-0166. on the epidermal features of the spikelets of the related genus Leersia. These same features were investigated in the oryzoid genus Zizania by Terrell and Wergin (198 1).Three new species of Oryza were not included in this study because they were unavailable and are thought to be closely related to other species included in this study, so they were not expected to contribute new data. They are Oryza meridionalis N.Q. Ng from Australia (Ng et al., 1981), which appears to be closely related to 0. sativa and 0. rufipogon; 0. rhizomatis Vaughan from Sri Lanka (Vaughan, 1990), said by Vaughan to have the same g...

An investigation of lemma micromorphology in Thai Oryzeae (Poaceae)

“…In general, epidermal features of paleas are similar to those of lemmas 20,21 . The micromorphology of lemma corresponds to that of palea.…”

“…After that, they were coated with platinumpalladium in a sputter coater (HITACHI E-102 ION SPUTTER) and photographed using an HITACHI S-2500 scanning electron microscope. The terminology used in this study mainly follows Metcalfe 24 , Terrell et al 21 , Terrell and Wergin 23 , and Terrell et al 22 .…”

“…In addition, Hoagland and Paul 19 used SEM to compare the surfaces of seeds and coleoptiles of red rice and other commercial varieties, while Thammawongsa et al 20 found that the lemma surface is a taxonomically valuable source of information when used in combination with other morphological and anatomical characters and were able to construct a key for the identification of 26 lowland black rice specimens. Even though epidermal features and spikelet micromorphology in Oryza and related genera including Leersia, Zizania, Rhynchoryza, and Porteresia have been examined using SEM method in previous studies [21][22][23] , not all taxa found in Thailand have been investigated. In particular, Hygroryza has never been studied in this way before, and no key for species-level identification based on micromorphological characters has been provided.…”

The homeotic gene long sterile lemma ( G1 ) specifies sterile lemma identity in the rice spikelet

“…1H). Convex structures called tubercles (30) are arranged in parallel and the cell files with a tubercle are very clear. In addition, trichomes are formed on the abaxial surface.…”

“…It is possible that G1 orthologs may be involved in morphological modification of the sterile lemma in lineages other than those of Oryza evolution. Alternatively, G1 function may be restricted to the sterile lemma of Oryza, because the epidermal convex structures (i.e., tubercles), which are suppressed by G1 in the sterile lemma, are a synapomorphy of the Oryza genus (16,30) and/or G1-related proteins may have diverse functions as a result of the insertion of amino acids, which are highly variable among grasses.…”