Identification of obligate C₃ photosynthesis in Dendrobium

Abstract

Dendrobium is one of the three largest genera in the Orchidaceae and is distributed throughout various habitats. We investigated photosynthesis in seven Dendrobium species and cultivars by comparing their leaf δ 13 C values, titratable acidity, and CO 2 exchange in well-watered and drought-stressed conditions. In addition, the leaf thickness and mesophyll succulence index (S m ) were measured in well-watered conditions. Our results indicate that Dendrobium loddigesii is a typical obligate (or constitutive) CAM plant because the leaf δ

Drought Stress Induced Different Response Mechanisms in Three Dendrobium Species under Different Photosynthetic Pathways

“…Orchidaceae is the largest family of flowering plants, and CAM photosynthesis is widespread in this family [ 39 , 40 ]. In Dendrobium , obligate CAM, C 3 /CAM intermediate, and obligate C 3 plant types distributed throughout various habitats [ 30 , 31 ]. Plants that undergo photosynthesis through the CAM pathway close their stomata during the day to reduce water loss and achieve greater drought tolerance [ 41 ], highlighting the need to study molecular regulation under drought stress using Dendrobium with different photosynthetic types.…”

“…Three Dendrobium species were selected in this study: D. fimbriatum was selected as an obligate C 3 plant, D. loddigesii as an obligate (or constitutive) CAM plant, and D. catenatum as a C 3 /CAM intermediate (inducible or facultative CAM) plant [ 30 , 31 ]. All the three wild species were obtained from the laboratory of Professor Shuo Qiu of the Guangxi Institute of Botany, complying with Chinese legislation, and came from Baise City, Guangxi Province, China.…”

“…However, some Dendrobium species, such as D. catenatum , can change between the C 3 and CAM pathways in response to stress or environmental changes [ 30 ]. D. loddigesii is a dedicated CAM pathway plant, which means that photosynthesis occurs via the CAM pathway regardless of drought [ 31 , 32 ]. Notably, Phosphoenolpyruvate Carboxylase (PEPC) catalyzing irreversible carboxylation of phosphoenolpyruvate and converting it to oxaloacetate plays an important role in the carbon–nitrogen metabolism of C 3 and CAM plants [ 33 , 34 ].…”

Dendrobium anosmum Lindl. introduzido em áreas verdes na Universidade Federal da Grande Dourados, UFGD

“…A elevada porcentagem de sobrevivência apresentada neste estudo pode estar associada ao metabolismo crassuláceo apresentado por espécies do gênero Dendrobium. Os indivíduos desse gênero são todos epifíticos e bastante flexíveis quanto às vias fotossintéticas que utilizam, variando entre as vias C3 e CAM (Winter & Ziegler, 1992;Rodrigues et al, 2013;Qiu, Sultana, Liu, Yin, Wang, 2015). Lüttge (2004) afirma que algumas espécies podem apresentar metabolismo C3 em ótimas condições ambientais e mudar naturalmente para a via CAM em condições de estresse, metabolismo este que oferece eficiente custo/benefício em relação ao consumo de água e absorção de CO2 (Silvera et al, 2010), aumentando assim a sobrevivência dessas plantas.…”

Qual a implicação do estresse hídrico na evolução do isolamento reprodutivo numa zona de hibridação natural de Epidendrum (Orchidaceae)?

“…Os discos foram acondicionados em tubos falcon contendo 50 ml de água destilada, fervidos por 10 min e, posteriormente, foi realizada a determinada a acidez com auxílio de NaOH (0,011 N) e fenolftaleína como substância indicadora (SIDERIS; YOUNG; CHUN, 1948;HARTSOCK;NOBEL, 1976;DAVIES;GRIFFITHS, 2012). A variação diária de acidez titulável (ΔH + ) foi calculada com a diferença de concentração obtida pela manhã e pela tarde e comparada entre os tratamentos e entre as espécies (QIU et al, 2015).…”