Standard karyotype and nomenclature system for description of chromosome bands and structural aberrations in wheat (Triticum aestivum)

Abstract

A standard karyotype based on N-banding, C-banding, and modified C-banding has been constructed for Triticum aestivum L. 'Chinese Spring'. An idiogram and a nomenclature system have been developed for the description of individual bands. Nomenclatural rules have been proposed for the description of chromosomal structural aberrations and polymorphic bands in other wheat cultivars. As a rule each short arm (S) and a long arm (L) consists of a series of dark bands (C-bands) and light bands (mainly euchromatic) and by definition there are no interbands. In some cases, each arm has been subdivided into two or more regions. The description of a band requires designation of a chromosome number, arm (S or L), region, and band. The region number is separated from the band number by a decimal point. Except for arms 1AS, 3AL, 4AS, and 6AS, all wheat chromosome arms have one or more intercalary C-bands and are divisible into three or more bands. It is hoped that the proposed karyotype and nomenclature system will be widely adopted and lay the foundation of definitive chromosome analysis in wheat.Key words: C-banding, N-banding, common wheat, heterochromatin, idiogram.