FLUXO DE PÓLEN EM ESPÉCIES SINCRONOPÁTRICAS NO SUDOESTE GOIANO

Abstract

Palicourea crocea and Psychotria carthagenensis are distillic species belonging to the family Rubiaceae, common to the Cerrado flora. Dysthily is a genetically controlled floral polymorphism that has as its main function the optimization of legitimate pollen flow between distinct morphs of the same species in a population. Pollen flow is an important interaction between species, as it leads to cross breeding and this in turn generates genetic diversity, an important factor for the maintenance of species in environments and resistance to environmental changes. Due to the large number of distillic species belonging to Rubiaceae, this study aimed to carry out a scientometric evaluation of the family's work on the subject, as well as to evaluate the floral characteristics of P. carthagenensis and P. crocea to evaluate the presence of dysthily in the population, in addition to its secondary flower polymorphisms and its anatomy. The results found for the sciometric evaluations showed that there are still few studies considering the size of the species and the number of distillic representatives. With collections performed in an anthropized environment, the flowers were stored in 70% alcohol for further analysis. The results of floral morphology showed that there were two morphos in the studied populations, however reciprocity tests showed that there was great variation in the height of reproductive structures, a factor that can lead to contamination with illegitimate pollen. The results found for the grain diameter evaluation revealed that the brevistilic morphus has larger pollen grains. The evaluation of pollen flow in the stigmas demonstrated a higher efficiency of the longistilic morphos for P. carthagenensis. For P. crocea the brevistilic morphus presented higher percentage of legitimate flow. Moreover, there was contamination with pollen from other species, which may be a result of the variation in height of reproductive parts observed in the populations evaluated. The morphology of the stigmatic papillae showed that P. carthagenensis has elongated papillae for both morphos, being thinner in the morpho longistilic, whereas P. crocea has rounded papillae for the morpho brevistilic and elongated papillae for the morpho longistilic. The anatomy of the flower of the two species is similar with petals composed of simple epidermis and fundamental parenchyma, and it is possible to observe some trichomes and idioblasts, besides P. crocea presenting papillae in its abaxial epidermis. Tetrasporanged anthers were also common to both species. Both bifid stigmas composed of mostly elongated stigmatic papillae with the exception of the P. crocea brevistilic morphus which has rounded papillae.