Abstract
Key messageGenome-wide introgressions of Thinopyrum bessarabicum into wheat resulted in 12 recombinant lines. Cytological and molecular techniques allowed mapping of 1150 SNP markers across all seven chromosomes of the J genome.Thinopyrum bessarabicum (2n = 2x = 14, JJ) is an important source for new genetic variation for wheat improvement due to its salinity tolerance and disease resistance. Its practical utilisation in wheat improvement can be facilitated through development of genome-wide introgressions leading to a variety of different wheat–Th. bessarabicum translocation lines. In this study, we report the generation of 12 such wheat–Th. bessarabicum recombinant lines, through two different crossing strategies, which were characterized using sequential single colour and multi-colour genomic in situ hybridization (sc-GISH and mc-GISH), multi-colour fluorescent in situ hybridization (mc-FISH) and single nucleotide polymorphic (SNP) DNA markers. We also detected 13 lines containing different Th. bessarabicum chromosome aberrations through sc-GISH. Through a combination of molecular and cytological analysis of all the 25 lines containing Th. bessarabicum recombinants and chromosome aberrations we were able to physically map 1150 SNP markers onto seven Th. bessarabicum J chromosomes which were divided into 36 segmental blocks. Comparative analysis of the physical map of Th. bessarabicum and the wheat genome showed that synteny between the two species is highly conserved at the macro-level and confirmed that Th. bessarabicum contains the 4/5 translocation also present in the A genome of wheat. These wheat–Th. bessarabicum recombinant lines and SNP markers provide a useful genetic resource for wheat improvement with the latter having a wider impact as a tool for detection of introgressions from other Thinopyrum species containing the J or a closely-related genome such as Thinopyrum intermedium (JrJrJvsJvsStSt) and Thinopyrum elongatum (EeEe), respectively.
Highlights
Genetic diversity in wheat was reduced during domestication resulting in a narrow gene pool hindering the development of superior wheat varieties especially in the current climate of plateauing crop yields and dynamic biotic threats
Wheat–Th. bessarabicum chromosome addition lines have been developed and studied allowing gene discovery for useful traits that can be further utilised in wheat improvement programmes (King et al 1996; William and MujeebKazi 1993, 1995; Xu et al 2009; Zhang et al 2002) but such addition and substitution lines are generally unsuitable for agronomic purposes, as many unwanted genes are introduced along with those giving rise to the trait of interest
We have developed a resource of single nucleotide polymorphic (SNP) markers spread across all seven Th. bessarabicum chromosomes which were used to identify 12 wheat–Th. bessarabicum recombinants and detect intact Th. bessarabicum chromosomes alongside spontaneous structural aberrations in introgression lines
Summary
Genetic diversity in wheat was reduced during domestication resulting in a narrow gene pool hindering the development of superior wheat varieties especially in the current climate of plateauing crop yields and dynamic biotic threats. Some genetic variation can be introduced through introgressions from its distant wild relatives (Able and Langridge 2006; Feuillet et al 2008; Gill et al 2011; Zhang et al 2017). These wild relatives are a largely unexploited source of agronomically important traits (Danilova et al 2017; Friebe et al 1996; Jauhar and Chibbar 1999; Schneider et al 2008). Wheat–Th. bessarabicum chromosome addition lines have been developed and studied allowing gene discovery for useful traits that can be further utilised in wheat improvement programmes (King et al 1996; William and MujeebKazi 1993, 1995; Xu et al 2009; Zhang et al 2002) but such addition and substitution lines are generally unsuitable for agronomic purposes, as many unwanted genes are introduced along with those giving rise to the trait of interest
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