Maytenus obtusifolia Mart. (Celastraceae): a tropical woody species in a transitional evolutionary stage of the gynodioecy–dioecy pathway

Abstract

Gynodioecy-dioecy' is one of the pathways by which dioecy can arise from hermaphroditism. Studies on sex determination and development of gynodioecious systems have focused on temperate and/or annual species.Little is known about the evolutionary dynamics of gynodioecy and dioecy in perennial tropical species, where these systems have more frequently evolved. Maytenus obtusifolia is an abundant species in restingas in southeastern Brazil. The sexual system of M. obtusifolia was investigated by studying the floral structure and reproductive biology. We considered the sexual system as an intermediate step in the pathway gynodioecy-dioecy. The characterization of the hermaphrodite morph was complex, because of a gradient of variation in floral morphology and reproductive characteristics (sizes of the style and stigmatic surface, pollen viability, embryo sacs containing hypertrophied synergids, and fruit set). This variation leads to different proportions of functional male and female flowers among hermaphrodite plants and is responsible for the different levels of reproductive success. Female reproductive success and pollen viability were negatively correlated with the hermaphrodite morph (r = -0.67). The higher fruiting intensity and fruit/flower ratio of females (41 %) compared to hermaphrodites (2 %) and the fact that female plants produce more and better-quality seeds support the female compensation. We suggest that female sterility may be linked to the set of changes in the carpels. The differences in the quality and quantity of pollen grains of hermaphrodite plants, and the similar individual rates of pollen viability observed for three consecutive flowering events, may indicate a relationship with nuclear cytoplasmic sex determination.

Aspectos reproductivos, arquitectura y fenomorfología de Maytenus boaria Molina (Celastraceae) en Chile central

“…La poca claridad en la caracterización del sistema sexual de M. boaria se repite no solo en especies del género Maytenus, como por ejemplo en Maytenus magellanica (Rodríguez et al 1983, Arroyo & Squeo 1990, Riedemann & Aldunate 2001, Hoffmann 2005, Barrera & Meza 2006, sino que también en especies de la familia Celastraceae (Brizicky 1964, Sebsebe 1985, Matthews & Endress 2005. Benevides et al (2013) postulan que esto puede tener relación con el tamaño pequeño de las flores y las modificaciones morfo-anatómicas de las estructuras femeninas y masculinas de las especies del género. Sin embargo, Donoso & Wendler (1985) indican que el polimorfismo tendría su origen en la plasticidad que presenta la especie.…”

“…Si bien en este estudio se visualizó la formación de frutos a partir de flores hermafroditas, estos no lograron desarrollarse, lo que se explicaría por abortos selectivos de los frutos (Sutherland & Delph 1984, Knight et al 2005. De acuerdo con Bawa & Webb (1984), el aborto de frutos puede influenciar el éxito reproductivo de la función femenina y masculina de las flores hermafroditas, teniendo en consideración que el gradiente de variación morfológica de estas flores puede repercutir en la funcionalidad sexual de las mismas (Benevides et al 2013). Por tanto, se presume que la mayoría de las flores perfectas que presenta M. boaria son morfológicamente hermafroditas, pero fisiológicamente masculinas.…”

Abiotic barriers limit tree invasion but do not hamper native shrub recruitment in invaded stands

“…Maytenus obtusifolia Mart. (Celastraceae), a shadetolerant (Matos 2014) evergreen native shrub that seldom grows taller than 5 m (Benevides et al 2013), occurs in several states of northeastern and southeastern Brazil (Lombardi et al 2015). In the restinga of the Costa do Sol State Park it is one of the most common species in the patchy shrub vegetation (Araújo et al 2009).…”

“…In the restinga of the Costa do Sol State Park it is one of the most common species in the patchy shrub vegetation (Araújo et al 2009). Individuals can be dioecious or hermaphrodites (Benevides et al 2013). Fruit production is mostly between January and April (T.G.…”

Modeling of the Leaf Area of <i>Maytenus obtusifolia</i> Mart. from Scanned Images

“…However, no work was found in the literature involving the species Maytenus obtusifolia Mart. due to the importance of the species, which is a shrub with a height of less than 5 m, belongs to the Celastraceae family, abundant in the Restinga region of southeastern Brazil and has its leaves used in folk medicine as analgesic, anti-inflammatory and antiulcerogenic [17] [18]. The aim of this study was to propose, test and adjust mathematical model equations that accurately estimate the leaf area of this species in a fast and non-destructive way through the [19].…”