6 research outputs found
rDNA mapping, heterochromatin characterization and AT/GC content of Agapanthus africanus (L.) Hoffmanns (Agapanthaceae)
Botanical aspects of Heteropterys umbellata (Malpighiaceae): a cytological and palynological approach
The genus Heteropterys is one of the major genera in Malpighiaceae. However, few cytological and palynological studies were reported. The present work described for the first time the chromosome number, heterochromatin pattern, meiotic behavior, pollen viability and palynological aspects of Heteropterys ubellata, a very spread species. One large Brazilian population was evaluated using conventional techniques for meiotic studies and acetolyse to access the pollen morphology. The species showed 2n = 20 chromosomes, normal meiotic development and viable pollens. Great blocks of heterochromatin were observed around the centromers. DAPI staining was positive for centroeric heterochroatin, hile CMA3 ark as observed just at terinal regions of one pair of hoologues chromosomes. This result and the presence of one chromosome pair attached to the nucleoli during the pachytene and diakinesis suggested the presence of only one pair of NORs. Palynological analysis revealed that pollen grains are apolar, 6 porate and with colpoids associated to all pores. The pollen content was positive for the starch test, and the exine was rugulate with little psilate regions.O gĂȘnero Heteropterys Ă© um dos maiores gĂȘneros entre as Malpighiaceae. Entretanto, poucos estudos citolĂłgicos e palinolĂłgicos foram relatados. O presente trabalho descreveu pela primeira vez o nĂșmero cromossĂŽmico, o padrĂŁo heterocromĂĄtico, o comportamento meiĂłtico, a viabilidade polĂnica e aspectos palinolĂłgicos de Heteropterys umbellata, uma espĂ©cie muito disseminada. Uma grande população brasileira foi estudada utilizando tĂ©cnicas convencionais para o estudo de cromossomos meiĂłticos e acetĂłlise para acessar a morfologia polĂnica. A espĂ©cie apresentou 2n = 20 cromossomos, desenvolvimento meiĂłtico normal e pĂłlens viĂĄveis. Grandes blocos de heterocromatina foram observados ao redor dos cen-trĂŽmeros. A coloração com DAPI foi positiva para a hetero-cromatina centromĂ©rica, enquanto marcas com CMA3 foram observadas somente em um sĂtio terminal de um par de cromossomos homĂłlogos. Este resultado e a presença de um par de cromossomos associados a um nuclĂ©olo durante o paquĂteno e diacinese sugerem a presença de somente um par de RONs. A anĂĄlise palinolĂłgica revelou que os grĂŁos de pĂłlen sĂŁo apolar, com 6 poros e colpĂłides associados a todos eles. O conteĂșdo polĂnico foi positivo para o teste de amido e a exina mostrou-se rugulada com poucas regiĂ”es psiladas
rDNA mapping, heterochromatin characterization and AT/GC content of Agapanthus africanus (L.) Hoffmanns (Agapanthaceae)
ABSTRACT Agapanthus (Agapanthaceae) has 10 species described. However, most taxonomists differ respect to this number because the great phenotypic plasticity of the species. The cytogenetic has been an important tool to aid the plant taxon identification, and to date, all taxa of Agapanthus L'Héritier studied cytologically, presented 2n = 30. Although the species possess large chromosomes, the group is karyologically little explored. This work aimed to increase the cytogenetic knowledge of Agapanthus africanus (L.) Hoffmanns by utilization of chromosome banding techniques with DAPI / CMA3 and Fluorescent in situ Hybridization (FISH). In addition, flow cytometry was used for determination of DNA content and the percentage of AT / GC nitrogenous bases. Plants studied showed 2n = 30 chromosomes, ranging from 4.34 - 8.55 ”m, with the karyotype formulae (KF) = 10m + 5sm. Through FISH, one 45S rDNA signal was observed proximally to centromere of the chromosome 7, while for 5S rDNA sites we observed one signal proximally to centromere of chromosome 9. The 2C DNA content estimated for the species was 2C = 24.4 with 59% of AT and 41% of GC. Our data allowed important upgrade for biology and cytotaxonomy of Agapanthus africanus (L.) Hoffmanns