Four distinct leaf types in the Brazilian cerrado, based on bundle sheath extension morphology

• Autor(a) principal: Rodrigues, Tatiane Maria [UNESP]
• Data de Publicação: 2017
• Outros Autores: Esteves Amaro, Amanda Cristina [UNESP], Fernandes Boaro, Carmen Silvia [UNESP], Mendes, Katiane Reis [UNESP], de Melo Silva, Stefany Cristina [UNESP], Ferreira Júnior, Valdemir [UNESP], Machado, Silvia Rodrigues [UNESP]
• Tipo de documento: Artigo
• Idioma: eng
• Título da fonte: Repositório Institucional da UNESP
• DOI: 10.1139/cjb-2017-0073
• Texto Completo: http://dx.doi.org/10.1139/cjb-2017-0073; http://hdl.handle.net/11449/175574
• topic: Bundle sheath extension; Leaf anatomy; Photosynthesis

Plant species have been classified as being either heterobaric or homobaric based on the presence or absence (respectively) of bundle sheath extensions (BSE) in leaf veins. These leaf types differ in their physiological performance, and their occurrences tend to be associated with environment. This study investigated the presence/absence of BSE and their structural peculiarities in 49 woody species (28 angiosperm families) in the Brazilian Cerrado using anatomical methods. We measured the gas exchange indices and stomatal density. In addition to typical homobaric (61.2%) and heterobaric (22.4%) species, we also found species with intermediate BSE features. These we call “larger heterobaric” (12.2%) and “semi-heterobaric” (4.1%) species. In the former, BSE occurs around only the secondary veins, whereas in the latter the BSE projects only towards the adaxial leaf surface. The net CO2 assimilation rates, the stomatal conductance, the transpiration rates, and the carboxylation efficiencies were statistically higher in heterobaric than in homobaric species. In the larger heterobaric species, the photosynthetic indices were similar to those in the heterobaric species. Meanwhile, semi-heterobaric species showed photosynthetic indices similar to the homobaric species. We demonstrated that structural variation in the BSE is linked to physiological leaf performance, suggesting some correlation between leaf morphology and plant adaptations.