Karyotype characterization of Malpighia emarginata (Malpighiaceae)

Malpighia emarginata Sessé & Mociño ex DC. or West Indian cherry (acerola) is a wild plant originated in southern Mexico, Central America and the northern region of South America. The species was introduced to Brazil about 60 years ago and now the country is the world's biggest producer. Even though the fruits of acerola have high commercial value, as they are an important source of the natural vitamin C, very little chromosome information is available for this species. Previous studies showed that most Malpighia species are diploids, including M. emarginata with 2n = 20. In the present paper, the chromosome number of acerola was confirmed, and for the first time, its karyotype was described, providing the identification of the homologues for the ideogram construction. The acerola chromosomes are small (1.71 to 2.56 µm) and metacentric with the exception of chromosome 2 that is classified as submetacentric. In addition, it is recommended a protocol to produce rooted-plantlets in vitro for mitotic studies that could be also used for micropropagation of acerola.

Karyotype and NOR-banding of mitotic chromosomes of some Vitis L. species

Chromosome studies were performed in V. champinii, V. cinerea, V. girdiana, V. labrusca, V. rotundifolia, V. rupestris and V. vinifera with the purpose of species characterization using chromosome morphometric data and NOR banding. A median ideogram was obtained for each species. The karyotype formula obtained varied from 7m + 12sm to 9m + 11sm. The species showed moderate chromosome asymmetry values according to TF% form, Stebbins, Romero Zarco and Paszko indices. V. champinii and V. girdiana were apart from the other species by CVcl and CVci graphic representation and also formed a group apart in the dendrogram based on Euclidian distances. The chromosome pair number 3 harbors the secondary constriction and a satellite segment in all species analyzed with Giemsa staining and it may be the same observed after NOR banding technique. It seems that the process of speciation in the North American Euvitis species studied involved some discrete changes in chromosome morphometry which have been reflected in the asymmetry index.

KARYOTYPE ANALYSIS IN GRAPEVINES

ABSTRACT Seven species of Vitis L., V. champinii Planchon, V. cinerea (Engelm in Gray) Engelm, V. girdiana Munson, V. labrusca L., V. rotundifolia Michaux, V. rupestres Scheels and V. vinifera L. were studied with the purpose of complementing the karyomorphometric information for further comparative analyses. Based on ideograms and on chromosome measures obtained it was possible to see several differences among the species, which were enough to distinguish at least V. champinii and V. girdiana from the others as well as V. labrusca for the lowest measures and V. rotundifolia for the highest mean value of arm ratio. It seems that during the species diversification process the most crucial differences among them did not involve drastic changes in chromosome morphometry.