ABSTRACT

Plants of the family Iridaceae are well represented in the grassland vegetation of southern Brazil, occurring in the Pampa and Atlantic Forest biomes. Nevertheless, little is known about the taxonomy and evolution of Iridaceae species in southern Brazil. The main goal of this review is to compile published information about South American Iridaceae, and to discuss the evolution and genetic diversity of the family presenting our own research data in the light of the published literature. The main focus is on the genera Calydorea, Cypella, Herbertia, and Sisyrinchium. Aspects of reproductive system and of pollinator attraction are also discussed.

Essential oils are widely found in plant species. They can be involved in a variety of ecological interactions and may act as inhibitors of germination, suppressing root apical-meristem growth in some species. The present study aimed to determine the potential cytotoxicity of essential oils from leaves of Heterothalamus psiadioides Less. and H. alienus (Sprengel) O.Kuntze on root tips of lettuce (Lactuca sativa L.) and onion (Allium cepa L.). Lettuce seeds germinated with essential oils from H. psiadioides and H. alienus had a reduced mitotic index (MI) for all treatments. Onion seedlings treated with H. psiadioides oil showed a decrease in MI, and seedlings treated with H. alienus oil showed a decrease in MI of 89% in the most concentrated treatment. Analysis of the results showed chromosomal abnormalities, including stickiness, c-mitosis, micronuclei and anaphase bridges in lettuce and onion root tips exposed to essential oils of Heterothalamus.

Resumo Esse artigo apresenta uma revisão sobre o uso de marcadores moleculares e citogenéticos aplicados à detecção da biodiversidade vegetal. São citados exemplos de aplicação destas ferramentas na investigação de táxons pertencentes às famílias de Monocotiledôneas, Iridaceae e Poaceae, que são alvo de pesquisa científica dos autores desse artigo. Palavras-chave: Marcadores moleculares, genética de populações, citotaxonomia, poliploidia, tamanho do genoma, genomas vegetais. AbstractWe present here a review of the use of molecular markers and cytogenetic data, applied to the detection of plant biodiversity. We mentioned a few examples of application of these tools in the investigation of taxa belonging to the families of monocotyledonous Iridaceae and Poaceae, which are the subject of scientific research of the authors of this review.

Myrtaceae are one of the largest families of flowering plants and are widely distributed in the Neotropics, where they are mainly represented by the tribe Myrteae. Myrteae are the most species-rich tribe of Myrtaceae and include groups with significant ecological and economic importance. Myrteae are considered to be a model group for biodiversity studies in the Neotropics, and so understanding the history of their diversification in this area is extremely important. The last decade has witnessed an increase in macro- and microevolutionary studies of the group, and summarizing this knowledge is now crucial to plan future steps in research on Myrteae. Here we provide the first overview of evolution and diversification studies on Myrteae, highlighting recent advances in understanding their evolutionary history. We discuss biogeography, phylogeny, phylogeography, population genetics, genomics and cytology in light of current knowledge. Finally, we provide perspectives and open hypotheses to be tested in future studies to fill gaps in the evolutionary knowledge of specific groups/taxa in Myrteae.

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South Brazilian grasslands are among the most species-rich grasslands worldwide yet they have been suffering ongoing degradation due to land-use. Little is known about the reproductive ecology of the native species of these grasslands. Thus, our goal was to characterize seed traits and germination requirements of three native species of the tribe Tigridieae (Iridaceae, Iridoideae) due to its richness in the Pampa biome and the contrasting morphology, cytogenetics, and geographic distributions of its representatives. We tested if closely related species possess similar seed traits and whether species with wider distributions have broader germination requirements. Seed production and mass were estimated, and morphological analyses, germination experiments and viability tests were performed. Principal component analysis (PCA) was used to describe correlations between seed traits and species' distributions. Germination was assessed using time-to-event analysis and the Cox model. All seed traits differed among the analyzed species/cytotypes. Final germination percentage (FGP) averaged 39.1 % and with overall viability of 89.9 %. Germination tests showed that seeds benefit from negative photoblasty. Species/cytotypes with wider distributions and heavier and larger seeds generally had better germination performances than narrower distributed species/ cytotypes with lighter and smaller seeds.

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