Genetic Relationship between Vasconcellea and Carica Based on Their Chromosome Features

Abstract

SummaryThe objective of this study was to evaluate the genetic relationship between five Vasconcellea species (V. cauliflora, V. goudotiana, V. quercifolia, V. monoica, and V. cundinamarcensis) and Carica papaya based on their chromosome features. To do that, five metaphase plates showing well spread and condensed chromosomes were used for the chromosome measurements: the absolute chromosome length (CL) and the lengths of the long (LA) and short (SA) arms. Further, we estimated the ratio between the arms (r), the centromeric index (CI), and the total length of haploid set (TLH). The Total Form index (TF%), the Rec, and the SYi were estimated for symmetry/ asymmetry of the karyotype. Most species show karyotype formulae of nine pairs of metacentric chromosomes (9m) except for V. goudotiana, which has five pairs of metacentric chromosomes and four pairs of sub-metacentric chromosomes (5m+4sm). V. goudotiana had the longest total length of haploid set, whereas V. quercifolia showed the shortest one. Based on the estimates of symmetry/ asymmetry indexes, four species have symmetric karyotype; moreover, V. goudotiana has asymmetric karyotype because it showed the lowest values of Syi and TF% index. The similarity matrix of five parameters for the six species was employed and based on the dendogram four clusters were formed; the first included C. papaya and V. cundinamarcensis, the second cluster was formed by V. monoica and V. cauliflora, the third by V. quercifolia and fourth by V. goudotiana. So, based on chromosome features V. cundinamarcensis, V. cauliflora, and V. monoica are closer to papaya than V. goudotiana.Key words Chromosome, Karyotype, Vasconcellea spp., Carica.The genus Vasconcellea (Caricaceae) was considered for a long time a section within the genus Carica L. (Badillo 1971). However, Badillo (2000, 2001 separated the monospecific section Carica from the section Vasconcellea, based on morphological and genetic evidence (Aradhya et al. 1999) rehabilitating the Vasconcellea section on generic level; since then the genus is formed by 25 species, and the Carica by only one, the cultivated form. Most of the Vasconcellea species has Ecuador as the center of origin or diversification, but V. microcarpa and V. cundinamarcensis are found in the Andes while V. cauliflora is found in Mexico (Badillo 1971). The Vasconcellea species are found at wild or at semi-domesticated conditions and five of them have been placed on

Cytological Characterization of Brazilian Green Dwarf Coconut (<i>Cocos nucifera</i> L.) <i>via</i> Meiosis and Conventional and Differential Karyotyping

“…Root tips of approximately 2 cm in length were collected from the Dwarf coconut seedlings, which were treated with paradichlorobenzene as an antimitotic solution for 10 h at 4 C to obtain the metaphases, according to Pereira et al (2014).…”