%0 Journal Article
%T Adiciones al conocimiento citogen¨¦tico de tithonia diversifolia (HEMSL.) A. gray (asteraceae)
%A de Guerra
%A Nilda Alcorc¨¦s
%A L¨¢rez R
%A Am¨¦rica
%A Mayz F
%A Juliana
%J Acta Bot¨¢nica Venezuelica
%D 2007
%I Fundaci¨®n Instituto Bot¨¢nico de Venezuela Dr. Tob¨ªas Lasser
%X with the objective of corroborating the chromosomal number, the pollen size, type and viability, in a study of the meiosis of tithonia diversifolia, meristematic root tips treated with colchicine (0,05%) and young inflorescence anthers, collected from different localities of monagas state, venezuela, were studied. a diploid chromosome number (2n = 34) was found,with 16 metacentric pairs and one submetacentric pair. lagging chromosomes in me-taphase i and anaphase i, and asynchrony in metaphase ii were observed. spermatic nuclei could not be seen in 65% of pollen grains. abnormalities which may be associated with the low pollen fertility (35%) were detected in this species. pollen grains were of triporate type and had muricate sculpture, with an average size of 26.5 mm. the microsporogenesis was of the simultaneous type.
%K chromosomes
%K cytogenetic
%K meiosis
%K microsporogenesis
%K mitosis
%K tithonia diversifolia.
%U http://www.scielo.org.ve/scielo.php?script=sci_abstract&pid=S0084-59062007000200001&lng=en&nrm=iso&tlng=en