Variation of karyotype and nuclear DNA content among four species of Plectranthus L’ Héritier, 1788 (Lamiaceae) from Brazil

Abstract

Plectranthus is a genus which includes species of ornamental and medicinal potential. It faces taxonomic problems due to aggregating species previously belonging to the genus Coleus, a fact that has contributed to the existence of various synonymies. The species Plectranthus amboinicus, Plectranthus barbatus, Plectranthus grandis and Plectranthus neochilus are included in this context. Some authors consider Plectranthus barbatus and Plectranthus grandis as synonyms. The present work was carried out with the aim of comparing plants of the above-mentioned species, originating from different localities in Brazil, with regards to chromosome number and karyotypic morphology, correlated to the nuclear DNA content. There was no variation in chromosome number among plants of the same species. Plectranthus amboinicus was the only species to exhibit 2n=34, whereas the others had 2n=30. No karyotypic differences were found among the plants of each species, except for Plectranthus barbatus. The plants of the Plectranthus species revealed little coincidence between chromosome pairs. The nuclear DNA content allowed grouping Plectranthus amboinicus and Plectranthus neochilus, with the highest mean values, and Plectranthus grandis and Plectranthus barbatus with the lowest ones. Differences in DNA amount among the plants were identified only for Plectranthus barbatus. These results allow the inference that the populations of Plectranthus amboinicus and Plectranthus neochilus present coincident karyotypes among their plants, and Plectranthus grandis is probably a synonym of Plectranthus barbatus.

Citogenética comparativa de Physalis peruviana en tres poblaciones cultivadas de Cajamarca, Perú

“…La diversificación de cariotipos puede ser considerada si se observan variaciones con relación a (1) número básico de cromosomas, (2) forma y tamaño relativo de los cromosomas, (3) número y tamaño de constricción secundaria y región satélite, (4) tamaño absoluto de los cromosomas y (5) localización de regiones eucromáticas y heterocromáticas (Cheema & Pant 2013y Furtado Nani et al 2015. Siendo así, los resultados obtenidos en las Tablas 6, 7,8 y 9 evidenciaron que las diferencias entre los cariotipos de San Pablo, Celendín y Cajabamba se basan en la forma y el tamaño relativo de los cromosomas de cada población en concordancia con el punto número dos señalado por Cheema y Pant (2013) y Furtado Nani et al (2015).…”