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Karyotype, rDNA localization and meiotic behavior of Hovenia dulcis Thunb. (Rhamnaceae)

Guidini, Caio César, Pinto-Maglio, Cecília Alzira Ferreira, Lombello, Ricardo Augusto
Caryologia 2017 v.70 no.4 pp. 385-389
Hovenia dulcis, chromosome number, chromosomes, evolution, karyotyping, meiosis, pollen, Asia
The species Hovenia dulcis, originally from Asia, was introduced in several Brazilian regions due to its ornamental features, edible fruits and medicinal properties. Despite its importance, few cytogenetic studies have been carried out with this species. Literature data present chromosome counts for H. acerba and H. dulcis (2n = 24) and propose the basic chromosome number x = 12 for Hovenia, with no karyomorphological information. In this way classical and cytomolecular studies were carried out in H. dulcis. This study presents the first meiotic analysis, the karyotype and the first cytomolecular analysis for a Rhamnaceae species. The meiotic analysis showed a regular process and a high rate of viable pollen grains (91.3%). The chromosome numbers were n = 12 and 2n = 24, reinforcing the basic number proposed for the genus. The chromosomes are small (1.5–2.8 μm) and metacentric and the karyotype is symmetric. Two CMA⁺ bands at secondary constriction of the longest chromosome were identified. One pair of 45S rDNA sites in distal position and one pericentromeric pair of 5S rDNA sites were observed. The stable chromosome number and the single pair of rDNA sites indicate the absence of neopolyploidy in karyotype evolution of H. dulcis.