ABSTRACT
Spondias tuberosa Arruda (Anacardiaceae), popularly known as umbuzeiro or imbuzeiro, is a fruit tree native to the semiarid region of Brazil. The extractive harvesting of its fruits contributes significantly to the economy, generating an annual revenue of approximately $4,2 million. The present study aimed to assess the spatial pattern, allometric variations, fruit measurements, and genetic diversity of trees within a remaining forest of the Caatinga biome, with a focus on intrapopulation analysis. We used intersimple repeated sequence markers and the second-order function density of neighbours to determine the genetic and spatial structure. The density of neighbours was highest within a 10-meter radius. Biometric analyses revealed average fruit lengths of 31.12 mm (±0.22), diameters of 28.68 mm (±0.25), and fresh masses of 15.56 g (±0.33). Diaspores exhibited an average length, diameter, and thickness of 19.27 mm, 13.95 mm, and 11.14 mm, respectively, with a fresh mass of 2.28 g. Notably, the fresh mass demonstrated the highest coefficient of variation. Ten molecular markers were selected, generating 103 highly polymorphic loci (99.03%) with an average informative content of 0.45. Nei's diversity index (0.37) and Shannon's index (0.55) indicated moderate genetic diversity. Furthermore, Bayesian analysis revealed a population structure with two distinct genetic groups. The Infinite Allele and Mutation Step Models suggested a significant historical decline in population size, indicative of a genetic bottleneck. As a result, proactive in situ conservation strategies, including establishing protected natural areas, become essential, considering the socioeconomic significance of the species. Additionally, it is recommended to establish germplasm banks for ex situ conservation and the development of managed cultivation initiatives to reduce the pressure on native populations of S. tuberosa caused by extraction.
ABSTRACT
This study evaluated the structure and the volume of interphase nuclei from root meristems of the genotypes of napier grass (Pennisetum purpureum), pearl millet (Pennisetum glaucum) and hybrids resultant of such breeding. In napier grass, nuclei were areticulate. Both pearl millet and the triploid hybrid had semi-reticulate nuclei; also, the hybrid presented a small proportion (6 percent) of areticulate nuclei. Pearl millet had the highest averages of nuclear dimensions, such as volume, diameter and radius, followed by the interspecific hybrid and napier grass. There was no intraspecific variation for the type of nuclear structure, which indicates this feature is important for cytotaxonomic studies involving the genus Pennisetum. Results demonstrated that chromatin organization in these nuclei was influenced by the number and size of chromosomes, affecting the nucleus volume in the analyzed taxa.
Avaliou-se, neste estudo, a estrutura e o volume de núcleos interfásicos de meristemas radiculares de genótipos do capim-elefante (Pennisetum purpureum), milheto (Pennisetum glaucum) e do híbrido resultante deste cruzamento. O capim-elefante apresentou núcleos do tipo arreticulado. Tanto no milheto como no híbrido triplóide os núcleos apresentaram-se semi-reticulados, sendo que, no híbrido, foi observada uma pequena proporção (6 por cento) de núcleos arreticulados. As maiores médias para as dimensões nucleares como volume nuclear, diâmetro e raio foram obtidas para o milheto, seguidas do híbrido interespecífico e capim-elefante. Não houve variação intraespecífica para tipo de estrutura nuclear indicando que essa característica tem relevância para estudos citotaxonômicos no gênero Pennisetum. Os resultados demonstraram que a organização da cromatina nesses núcleos foi influenciada pelo número e tamanho dos cromossomos e essa afetou o volume nuclear dos táxons analisados.
