Floral, reproductive and pollinators biology of Myrcianthes pungens (Berg) Legrand, neglected species

Studies related to floral biology are essential for the understanding of the ecological relations between different species, and the beginning of breeding programs. In this way, the aim of the study was to elucidate aspects of floral and reproductive biology and floral visitors of this species. Information about floral morphology and morphometry, anthesis, nectaries and pollinator attractive structures, characterization of floral visitors, receptivity of androcytic stigma and maturation, in vitro pollen storage and germination, and characterization of the reproductive system were obtained. The guabiju tree has hermaphrodite flowers, and the floral opening occurs mainly during the night, but also in the morning. Anthers are the main attractive structure to the pollinating insects, releasing fetid odor, attracting mainly flies and wasps characterized as occasional pollinators, and moths characterized as effective pollinators. For the germination of pollen, it is recommend using it without desiccation, collected in post-anthesis, and for the culture medium the use of 11% of sucrose and 7% of boric acid. Pollen presents recalcitrant behavior, so even when stored in refrigerator, freezer, liquid nitrogen and natural environment lose viability in less than 30 days. It presents high reproductive efficiency, and can be considered self-compatible; however, fertilization also occurs by cross-pollination.

Reproductive success and genetic diversity of Psychotria hastisepala (Rubiaceae), in fragmented Atlantic forest, Southeastearn Brazil

The impacts of forest fragmentation on both reproductive biology and genetic diversity of native plant species is hardly understood, despite some studies have analyzed this current worldwide problem. Since this constitutes one of the main threats to seasonal semi-deciduous forests in Southeastern Brazil, we investigated the reproductive success and the genetic diversity of a distylous, understory shrub (Psychotria hastisepala) within this context of forest fragmentation. For this study, a set of seven forest fragments of sizes ranging from 4.1 to 168.7 hectares were chosen. The intervenient matrix comprised pastures (25-50%), monocultures (33-50%) and rural roads and buildings (14-28.5%). Overall, 91 plants (54 for the short-styled morph and 37 for the long-styled morph; mean of 6.5 plants per fragment) were investigated. To evaluate reproductive success, we quantified fruit and seed production under natural pollination; to evaluate genetic diversity and population structure, we employed ISSR markers on genomic DNA. Plants with the short-styled morph exhibited a significantly higher reproductive success than those with the long-styled morph; there was no association between seed production and size of the forest fragment. Levels of genetic diversity were positively associated with the number of plants per fragment; but they were not related to flower morph. AMOVA showed that about 65% of the overall genetic variation was attributed to the differences between plants within fragments. The results suggested that populations of P. hastisepala were susceptible to decline owing to forest fragmentation. Rev. Biol. Trop. 62 (1): 309-319. Epub 2014 March 01.

Los impactos de la fragmentación de los bosques tanto en la biología reproductiva como en la diversidad genética de las especies de plantas nativas apenas se entienden, a pesar de que algunos estudios han analizado este problema mundial. Dado que esto constituye una de las principales amenazas para los bosques semi-deciduos estacionales en el sureste de Brasil, se investigó el éxito reproductivo y la diversidad genética de un arbusto de sotobosque, Psychotria hastisepala, en un bosque fragmentado. Para este estudio, se seleccionaron siete fragmentos de tamaños que van desde 4.1 hasta 168.7 hectáreas. La matriz intervenida comprende pastos (25-50%), monocultivos (33-50%) y carreteras y edificios rurales (14-28.5%). En total, 91 plantas fueron investigadas (54 morfos florales brevistilo y 37 longistilo, con una media de 6.5 plantas por fragmento). Para evaluar el éxito reproductivo, se cuantificó la producción de frutos y semillas de plantas con polinización natural; para evaluar la diversidad genética y la estructura poblacional, se emplearon marcadores ISSR en el ADN genómico. Las plantas con morfo brevistilo exhibieron un éxito reproductivo significativamente más alto que las longistilo, no hubo asociación entre la producción de semillas y el tamaño del fragmento de bosque. Los niveles de diversidad genética se asociaron positivamente con el número de plantas por fragmento, pero que no estaban relacionados con los morfos florales. AMOVA mostró que alrededor del 65% de la variación genética en general se atribuyó a las diferencias entre plantas dentro de fragmentos. Los resultados sugieren que las poblaciones de P. hastisepala fueron susceptibles a disminuir debido a la fragmentación de los bosques.