Cytogenetic and palynological studies in species of Chrysolaena (Vernonieae,

VIA DO PICO GISELA M.; DEMATTEIS MASSIMILIANO

San Pablo

Encuentro; South American Compositae meeting; 2011

FAPESP: Fundação de Amparo à Pesquisa do Estado de São Paulo.

The genus Vernonia Schreb. was segregated to several new genera being restricted mainly to North America. One of the recently segregated genera is Chrysolaena H.Rob. which comprises about 18 species distributed in South America, mainly in southern Brazil, Paraguay and Argentina. This genus differs from the other South American members of the tribe by the presence of sericeous or velutinous indumentum, anthers glandular apical appendages, style without basal node and cypselas with glands. Also can be separated from other American groups by the morphology of the pollen grains (tricolporate, echinolophate, with irregular lacunae and colpi ending in a polar lacuna) and especially by the basic chromosome number x=10 (numeral mainly present in the Old World Vernonieae). This group has been poorly studied from the cytological point of view and it is only known the chromosome numbers of some species. The limited information available in this area shows that chromosomes are variable in number and morphology, suggesting that could be used in taxonomic and evolutionary studies. The species of the genus have different ploidy levels and chromosome numbers ranging from 2n=20 to 2n=80. With regard to the palynology, pollen morphology is one of the most used features for taxonomic studies in the tribe Vernonieae and this was one of the characters considered for the segregation of Vernonia in different genera. According to the current classification of the tribe, Chrysolaena has pollen type C. In this work we presented chromosome counts, ploidy levels, karyotypes, genome size, meiotic behavior and pollen morphology of some species of Chrysolaena in order to broaden the cytological and palynological information of the group.