Seasonal variation in colleter exudates in Myrcia splendens (Myrtaceae)

Abstract

Colleters are secretory structures that play a role in protecting meristems from dehydration. Little attention has been given to the effect of seasonal variation on colleter exudates. Therefore, this study aimed to characterise the main chemical groups found in colleter exudates as well as to correlate the chemical nature of the secretion with seasonal variation. We used Myrcia splendens as a model to understand seasonal variation in colleter exudates. For that, meristems and shoot apices of M. splendens were collected and subjected to standard anatomical techniques. In M. splendens, colleters arise from protodermal cells and are similar to trichomes. Mature colleters are conic and composed of a short stalk and a long secretory head. Histochemical analyses found that colleter exudates differed according to the seasonality. Composition of the secretions was more diverse in the dry season than in the wet season. During the dry season, colleters secreted five different compounds (i.e. total polysaccharides, mucilage–pectins, total proteins, total lipids and phenolic compounds), whereas in the wet season, only three compounds were found (i.e. total proteins, total lipids and phenolic compounds). Our study extends what was known in earlier works, demonstrating changes in colleter exudates due to environmental seasonality.

Structural and histochemical attributes of secretory ducts and cavities in leaves of four species of Calophyllaceae J. Agardh in Amazonian savannas

“…The metabolites of the duct and cavity secretions are similar among the studied species; however, the presence of essential oils without oleoresins makes K. coriacea different from the other species and may indicates diagnostic value (Stojanovic et al, 2015). Another possible explanation for the absence of oleoresin in K. coriacea may be the result of seasonal variations in secretion, as reported by Costa et al (2020a) in Myrcia splendens (Sw.) DC. (Myrtaceae) or a specific response of K. coriacea to different conditions of the phytophysiognomy to which it is inserted (Wink 2003).…”

“…Mucilage acts in water retention in cell protoplasm, prevents leaf desiccation and ensures the maintenance of vital processes (Sawidis 1998;Galloway et al, 2020). Costa et al (2020a) correlated the main groups of metabolites in the secretion of colleters in Myrcia splendens (Sw.) DC. (Myrtaceae) with seasonal variations, where mucilage and neutral polysaccharides were found in the dry season.…”

Anatomical inferences on aerial bud protection of three Eugenia shrub species from the Cerrado

“…The presence of protein in the colleter exudate, also described in Myrcia splendens (Myrtaceae) (Costa et al . 2020), may effectively prevent growth of fungal spores, as reported for Bathysa nicholsonii (Rubiaceae) (Castro Miguel et al . 2010).…”

Sistema subterrâneo e proteção das gemas aéreas de >i<Psidium grandifolium>/i< Mart. Ex Dc. ocorrentes em área de Cerrado natural e Cerrado em regeneração

“…Coléteres estavam presentes protegendo os ápices caulinares de todas as gemas aéreas da espécie estudada. Em Mrytaceae, coléteres já foram descritos nos ápices vegetativos e na base das axilas foliares em diferentes gêneros da família, sendo a morfologia cônica a mais recorrente entre as espécies (Costa et al, 2020;Da Silva et al, 2012;Silva et al, 2019;. Os coléteres de P. grandifolium analisados nas plantas das suas áreas são cônicos, não-vascularizados, sésseis, de base ampla e desprovidos de epiderme em paliçada como descritos por Silva e colaboradores (2019).…”

“…A secreção mucilaginosa dos coléteres desempenha importante papel na proteção das gemas aéreas, pois a natureza higroscópica e viscosa da secreção, mantem as regiões meristemáticas hidratadas em locais com baixa umidade do ar, alta incidência solar e temperaturas elevadas (Da Silva et al, 2012;Thomas, 1991). Estudos recentes demonstram que a secreção dos coléteres é influenciada tanto pelo local de ocorrência quanto por uma sazonalidade marcante (Costa et al, 2020;Tresmondi et al, 2017 Os testes histoquímicos evidenciaram que os compostos fenólicos estavam presentes em todas as estruturas analisadas, tanto na parte aérea quanto na parte subterrânea. O acúmulo de compostos fenólicos, no conteúdo celular dos tricomas não-glandulares e nas camadas epidérmicas e subepidérmicas dos primórdios foliares, além da proteção contra herbivoria, conferem maior resistência aos danos da radiação solar e comprimentos de ondas prejudicais (Karabourniotis et al, 2020;Kulbat, 2016).…”