Meiosis en Cydista aequinoctialis (L.) Miers. (Bignoniaceae)

Abstract

The genus Cydista Miers., belongs to the Bignoniaceae family and includes 14 species and three varieties corresponding to C. aequinoctialis var. aequinoctialis, var. hirtella and var. sarmentosa. In the Bignoniaceae family there is a high diversity in the pollen characteristics, the most frequent type is the tricolpate, monocolpates, inaperturate and four to five colpate. Basic chromosome number of most tribes is x=20 and the species studied Tabebuia chrysantha, T. capitata, T. ochracea subespecies neochrysantha and ochracea and T. aquatilis are diploid (2n=40). Chromosome number of C. aequinoctialis is known. This research was carried out to confirm the chromosome number and to provide more information about their cytogenetic. In meiosis I, prophase and metaphase, normal cells were observed and anaphase and telophase, meiotic abnormalities as lagged and non-aligned chromosomes were observed. In meiosis II, tetragonal tetrads and anomalies were observed in telophase II, tricolpate pollen with reticulate sculpture, circular to elliptical form, size 3.64 ± 0.19 ìm for circular ones and 3.71 ± 0.22 to 3.55 ± 0.21 ìm for the elliptical ones, the latter at a higher percentage. The high rate of cells with chromosome anomalies could be one of causes of the low seed production in the fruits. It was concluded that the haploid chromosome number is n=20.El genero Cydista Miers., pertenece a la familia Bignoniaceae e incluye 14 especies y (3) variedades correspondientes a C. aequinoctialis var. aequinoctialis, var. hirtella y var. sarmentosa. En la familia Bignoniaceae hay una alta diversidad en las caracteristicas del polen, encontrandose que el mas frecuente que se presenta es del tipo tricolpado, monocolpado, inaperturado y cuatro a cinco colpado. El numero cromosomico basico de casi todas las tribus es x=20 y las especies estudiadas Tabebuia chrysantha, T. capitata, T. ochracea subespecies neochrysantha y ochracea y T. aquatilis son diploides (2n=40). De C. aequinoctialis solo se conoce su numero cromosomico. La presente investigacion pretendio corroborar el numero cromosomico y aportar mas informacion acerca de su citogenetica. En meiosis I, profase y metafase, se observaron celulas normales y anomalias meioticas como cromosomas rezagados y no alineados en anafase y telofase. En la meiosis II se observo tetradas tetragonales y anomalias en telofase II, polen tricolpado con escultura reticulada, de forma circular a eliptica, tamano 3,64 } 0,19 Êm para los circulares y de 3,71 } 0,22 Êm a 3,55 } 0,21 Êm para los elipticos, estos ultimos en mayor porcentaje. El alto porcentaje de celulas con anomalias cromosomicas detectadas, podria ser una de las causas de la escasa produccion de semillas en los frutos. Se concluye que el numero cromosomico haploide de la especie es n=20