Portal de Periódicos da CAPES

Artigo Produção Nacional Revisado por pares

BIBTEX RIS

Anatomical adaptations in the stem of Discocactus catingicola (Cactaceae) to the highly threatened ironstone outcrops from southeastern Brazil

2023; Elsevier BV; Volume: 305; Linguagem: Inglês

10.1016/j.flora.2023.152346

1618-0585

Natasha Noeme Miranda Lobo, Guilherme Carvalho Andrade, Ana Paula de Oliveira, Silvana da Costa Ferreira, Jaqueline Dias-Pereira,

Botany, Ecology, and Taxonomy Studies

The geosystems known as "cangas" are composed of ferruginous concretions and are characterized by being subjected to elevated temperatures and by having highly acidic, shallow, unfertile soils. The extremely harsh environmental conditions therein limit the occupation of cangas to a restricted number of species, such as Discocactus catingicola. We aimed to analyze the stem anatomy of D. catingicola occurring on cangas in order to assess which structural traits provide the species with an adaptive advantage to these geosystems. Stem samples were subjected to protocols of cross-sectioning, epidermal dissociation and lugol histochemical detection, and were then analyzed under light microscopy. Stems have a uniseriate epidermis and a thick cuticle. Paracytic stomata occur at the same level of pavement cells. Conspicuous substomatal chambers extend through the entire hypodermis height. The two-layered, collenchymatous hypodermis has a high amount of calcium oxalate inclusions in the form of prismatic crystals. Stem structure is also composed of a water-storing chlorenchyma, a starch and water storage parenchyma, and wide-band tracheids. Our findings revealed the occurrence of xeromorphic adaptive characters in D. catingicola which provide the species with its adaptive success in ironstone outcrops. The description of these anatomical traits in D. catingicola make up a pioneer report, thus being of great importance for future research on ecological plant anatomy not only of Cactaceae species but also of other unrelated xerophytes. We expect our work will assist researchers in the fields of anatomy, taxonomy and systematics of Cactaceae. Future research investigating the anatomy of D. catingicola populations occurring on ecosystems other than the lateritic cangas should provide a helpful comparative basis for evaluating the species degree of phenotypic plasticity.