Phylogenetic and evolutionary features of the plastome of Tropaeolum pentaphyllum Lam. (Tropaeolaceae).

MAIN CONCLUSION: Complete plastome sequence of Tropaeolum pentaphyllum revealed molecular markers, hotspots of nucleotide polymorphism, RNA editing sites and phylogenetic aspects Tropaeolaceae Juss. ex DC. comprises approximately 95 species across North and South Americas. Tropaeolum pentaphyllum Lam. is an unconventional and endangered species with occurrence in some countries of South America. Although this species presents nutritional, medicinal and ornamental uses, genetic studies involving natural populations or promising genotypes are practically non-existent. Here, we report the nucleotide sequence of T. pentaphyllum plastome. It represents the first complete plastome sequence of the family Tropaeolaceae to be fully sequenced and analyzed in detail. The sequencing data revealed that the T. pentaphyllum plastome is highly similar to the plastomes of other Brassicales. Notwithstanding, our analyses detected some specific features concerning events of IR expansion and structural changes in some genes such as matK, rpoA, and rpoC2. We also detected 251 SSR loci, nine hotspots of nucleotide polymorphism, and two specific RNA editing sites in the plastome of T. pentaphyllum. Moreover, plastid phylogenomic inference indicated a closed relationship between the families Tropaeolaceae and Akaniaceae, which formed a sister group to Moringaceae-Caricaceae. Finally, our data bring new molecular markers and evolutionary features to be applied in the natural population, germplasm collection, and genotype selection aiming conservation, genetic diversity evaluation, and exploitation of this endangered species.

Mating System and Genetic Structure Across All Known Populations of Dyckia brevifolia: A Clonal, Endemic, and Endangered Rheophyte Bromeliad.

Dyckia brevifolia is an endemic rheophyte bromeliad that occurs exclusively in patches on rocky banks of the Itajaí-Açu River in southern Brazil. The genetic diversity of all known populations was carried out using allozyme markers and the total numbers of rosettes, reproductive rosettes, and clumps per population were characterized. The mating system was also investigated. Most rosettes were aggregated in groups, and the populations differed significantly in number of rosettes and reproductive rosettes per population. The outcrossing rate obtained was 8.2%, with predominant selfing. The populations presented an average of 1.4 alleles per locus and 27% of polymorphisms. The mean expected genetic diversity was 0.067. Downstream populations showed the highest genetic diversity which could be attributed to hydrochory (unidirectional river flow). Most genetic diversity is distributed among populations (F^ST = 0.402). Natural habitats of D. brevifolia are not recommended for the construction of hydroelectric plants given that it would seriously complicate in situ conservation of this species. Based on the results of this study, it can be concluded that between 35 and 161 reproductive rosettes must be collected for effective ex situ conservation, depending on the targeted population, or seeds collected from 157 seed-rosettes per population.