Ontogenesis of stomata in Velloziaceae: paracytic versus tetracytic?

Abstract

-(Ontogenesis of stomata in Velloziaceae: paracytic versus tetracytic?). In Velloziaceae, the number of subsidiary cells has been used to characterize species and support groups. Nevertheless, the homology of the stomatal types have not been scrutinized. Stomatal ontogenesis of Vellozia epidendroides and V. plicata, assigned to have tetracytic stomata, and of V. glauca and Barbacenia riparia, assigned to have paracytic stomata, were investigated. In the four species studied, stomata followed perigenic development. Subsidiary cells arise from oblique divisions of neighbouring cells of the guard mother cell (GMC). These cells are elongated and parallel to the longer axis of the stoma. Polar cells show wide variation, following the shape and size of the epidermal cells in the vicinity. Hence, these cells cannot be called subsidiary cells. This wide variation is due to a much higher density of stomata in some regions of the leaf blade. This distribution of stomata forces the development of short polar cells, leading to an apparently tetracytic stomata. In regions of low concentration of stomata, higher spatial availability between the GMCs allows the elongation of polar cells, leading to evident paracytic stomata. Therefore, the four studied species are considered braquiparacytic, questioning the classification of stomata into tetracytic and paracytic in Velloziaceae.Key words -ontogenesis, paracytic, stomata, tetracytic, Velloziaceae RESUMO -(A ontogênese dos estômatos em Velloziaceae: paracítico versus tetracítico?). Em Velloziaceae, o número de células subsidiárias tem sido utilizado para caracterizar espécies e sustentar grupos. Entretanto, a homologia dos tipos de estômatos nunca foi escrutinizada. Para isso, a ontogênese dos estômatos de Barbacenia riparia e Vellozia glauca, representando estômatos paracíticos, e V. epidendroides e V. plicata, representando estômatos tetracíticos, foi investigada. Nas quatro espécies, foi evidenciada ontogênese perígina. As células subsidiárias se originam a partir de divisões oblíquas das células vizinhas da célula-mãe de células-guarda (GMC), que são alongadas paralelamente em relação ao maior eixo do estômato. Células polares apresentam grande diversificação, acompanhando o padrão de tamanho e formato das outras células epidérmicas, e assim não podem ser denominadas células subsidiárias. Essa ampla variação se deve a uma maior densidade de estômatos em algumas regiões da superfície foliar, forçando o desenvolvimento de células polares curtas e conduzindo a estômatos aparentemente tetracíticos. Em regiões de baixa concentração de estômatos, a maior disponibilidade espacial entre GMCs permite o alongamento de células polares, conduzindo a estômatos evidentemente paracíticos. Os estômatos das quatro espécies são então classificados como braquiparacíticos. A classificação de estômatos em tetracítico e paracítico em Velloziaceae deve ser questionada.

Anatomical Studies on the Genus Terminalia L. (Combretaceae) in Egypt I- Leaf Structure

“…The presence of a thin cuticle helps protection against multiple stress factors including dehydration (Gonzalez, 2002). The epidermal characteristics have been utilized for taxonomic specification of taxa at the genus and family levels (Van Cotthem, 1970;Paliwal et al, 1980;Naidu & Shah, 1981;Das, 2002;Agbagwa & Okoli, 2005Amaral & Mello-Silva, 2008). Particularly, Ramassamy & Kannabiran (1994) used the epidermal characteristics as stomata and trichome types for taxonomic considerations of some Terminalia species in India.…”

Comparative anatomical study of leaves for twelve Indonesian woody plant species

“…Different plant species contributed to the variation of this trait in different ways (Hong et al 2018). Guard cells are distinct from regular epidermal cells in that they are specialized structures (Amaral and Mello-Silva 2008;Rahayu et al 2012). In systematics, the number and arrangement of secondary cells have long been employed as a character (Amaral and Mello-Silva 2008;Shtein et al 2017).…”

“…Guard cells are distinct from regular epidermal cells in that they are specialized structures (Amaral and Mello-Silva 2008;Rahayu et al 2012). In systematics, the number and arrangement of secondary cells have long been employed as a character (Amaral and Mello-Silva 2008;Shtein et al 2017). Stomatal pores in the aerial epidermis are not only important ecologically, but they constitute one of the most persistent micromorphological traits in terrestrial plant evolution (Rudall et al 2013).…”

Epidermal Structures and Stomatal Ontogeny in Terminalia catappa L. (Combretaceae)

“…Epidermal characteristics in general and ontogeny of stomata in particular have been utilized at different times for taxonomic delimitation of taxa at the genus and family levels (Van Cotthem, 1970;Paliwal et al, 1980;Naidu and Shah, 1981;Das, 2002;Okoli, 2005, 2006;Amaral and Mello-Silva, 2008;Abubakar et al, 2011). The number, arrangement, size and shape of subsidiary cells surrounding the guard cells have also proven to be of great taxonomic value in angiosperms (Stace, 1984;Tomlinson, 1974;Esau, 1977;Baranova, 1987;Stebbins and Khush, 1961;Metcalfe and Chalk, 1979;Okoli, 2005, 2006).…”