Enhanced Resolution of Somatic Chromosome Constrictions as an Aid to Identifying Intergeneric Hybrids among Some Triticeae

Abstract

Intergeneric hybridization research efforts among Triticeae have been the object of increased interest during the last decade. The genera utilized in crosses have been Aegilops, Agropyron, Elymus, Haynaldia, Hordeum, Secale and Triticum. Successful combinations set seeds i) that reach maturity on the female plant, or ii) from which the immature embryos require extraction and culturing; a procedure necessary for several intergeneric combinations as a consequence of endosperm collapse or of its complete absence. In either case, confirmation of hybridity is initially obtained by a root-tip cytological check conducted either before or after the transfer of young plantlets to peat pots or to soil in pots. A confirmed hybrid possesses half the chromosome complement of each parent, is self-sterile, and expresses explicit clarity at metaphase for primary and secondary chromosome constriction regions. To facilitate the above cytological requirements, ideal chromosome contraction, metaphase spreads and quality staining are essential. In addition, sample storage and ease of preparation require that the cytological technique possesses adequate operational flexibility. This paper describes said technique, and includes photomicrographs of metaphase squashes of root-tip cells of intergeneric hybrids among some Triticeae so as to substantiate the technique's merits. © 1985, Japan Mendel Society, International Society of Cytology. All rights reserved.