Cytogenetic study of diploid and spontaneous triploid oaks, Quercus robur L

Abstract

— Data are presented on the cytogenetics of 2 unusually large oak trees found in the Voronezh region of Russia. In both trees, cells with 2n = 3x = 36 chromosomes were predominant, with occasional observations of diploid hypoaneuploid and hyperaneuploid cells. Functionally, the trees can be considered triploids, although in a strict sense, they are mixoploids. Meiosis in micro-sporogenesis of these trees is very disturbed and, as a consequence, pollen with unbalanced chromosome numbers are produced. Correspondingly, the progeny from each tree were very different in morphological characteristics and cytogenetic constitution. These progeny can be used in gene mapping studies and for other basic research purposes. Studies on some diploid oaks reveal the presence of 2n pollen, formed by parallel spindles in the 2nd meiotic division. Methods for producing additional oak triploids that have a potential for heterosis are discussed. oak / triploid / mixoploid / meiosis / meiotic mutant / progeny Résumé — Cytogénétique de chênes diploïdes et triploïdes spontanés (Quercus robur L). Des données cytogénétiques relatives à 2 chênes de très grande taille situés dans la région de Vo-ronezh (Russie) sont présentées dans cet article. Des cellules comprenant 2n = 3x = 36 chromosomes sont prédominantes dans chaque arbre. Des cellules hypoaneuploïdes et hyperaneuploïdes ont également été rencontrées. Au plan fonctionnel, les 2 arbres peuvent être considérés comme tri-ploïdes, plus précisément mixoploïdes. La méiose durant la microsporogenèse est très perturbée et produit des grains de pollen au nombre de