Cytological analyses of hybrids and derivatives of hybrids between durum wheat and <i>Thinopyrum bessarabicum</i>, using multicolour fluorescent GISH*

Abstract

Abstract The wheat progenitors and other wild relatives continue to be important sources of genes for agronomically desirable traits, which can be transferred into durum wheat ( Triticum turgidum ; 2 n = 4 x = 28; AABB genomes) cultivars via hybridization. Chromosome pairing in durum × alien species hybrids provides an understanding of genomic relationships, which is useful in planning alien gene introgression strategies. Two durum cultivars, ‘Lloyd’ and ‘Langdon’, were crossed with diploid wheatgrass, Thinopyrum bessarabicum (2 n = 2 x = 14; JJ), to synthesize F 1 hybrids (2 n = 3 x = 21; ABJ) with Ph1 . ‘Langdon’ disomic substitution 5D(5B) was used as a female parent to produce F 1 hybrids without Ph1 , which resulted in elevation of pairing between durum and grass chromosomes – an important feature from the breeding standpoint. The F 1 hybrids were backcrossed to respective parental cultivars and BC 1 progenies were raised. ‘Langdon’ 5D(5B) substitution × Th. bessarabicum F 1 hybrids were crossed with normal ‘Langdon’ to obtain BC 1 progeny. Chromosome pairing relationships were studied in F 1 hybrids and BC 1 progenies using both conventional staining and fluorescent genomic in situ hybridization (fl‐GISH) techniques. Multicolour fl‐GISH was standardized for characterizing the nature and specificity of chromosome pairing: A–B, A–J and B–J pairing. The A–J and B–J pairing will facilitate gene introgression in durum wheat. Multicolour fl‐GISH will help in characterizing alien chromosome segments captured in the durum complement and in their location in the A and/or B genome, thereby accelerating chromosome engineering research.