Introgression of the Aegilops speltoides Su1-Ph1 Suppressor into Wheat

Abstract

Meiotic pairing between homoeologous chromosomes in polyploid wheat is inhibited by the Ph1 locus on the long arm of chromosome 5 in the B genome. Aegilops speltoides (genomes SS), the closest relative of the progenitor of the wheat B genome, is polymorphic for genetic suppression of Ph1. Using this polymorphism, two major suppressor loci, Su1-Ph1 and Su2-Ph1, have been mapped in Ae. speltoides. Su1-Ph1 is located in the distal, high-recombination region of the long arm of the Ae. speltoides chromosome 3S. Its location and tight linkage to marker Xpsr1205-3S makes Su1-Ph1 a suitable target for introgression into wheat. Here, Xpsr1205-3S was introgressed into hexaploid bread wheat cv. Chinese Spring (CS) and from there into tetraploid durum wheat cv. Langdon (LDN). Sequential fluorescence in situ hybridization and genomic in situ hybridization showed that an Ae. speltoides segment with Xpsr1205-3S replaced the distal end of the long arm of chromosome 3A. In the CS genetic background, the chromosome induced homoeologous chromosome pairing in interspecific hybrids with Ae. peregrina but not in progenies from crosses involving alien disomic substitution lines. In the LDN genetic background, the chromosome induced homoeologous chromosome pairing in both interspecific hybrids and progenies from crosses involving alien disomic substitution lines. We conclude that the recombined chromosome harbors Su1-Ph1 but its expression requires expression of complementary gene that is present in LDN but absent in CS. We suggest that it is unlikely that Su1-Ph1 and ZIP4-1, a paralog of Ph1 located on wheat chromosomes 3A and 3B and Ae. tauschii chromosome 3D, are equivalent. The utility of Su1-Ph1 for induction of recombination between homoeologous chromosomes in wheat is illustrated.

Manipulation of crossover frequency and distribution for plant breeding

“…Some alternatives to mutagenesis have been proposed for overriding Ph1 activity. These are based on the use of genes found in wheat wild relatives (Sears 1976 ) such as Amblyopyrum muticum (Dover and Riley 1972 ; see also King et al 2017 and ref therein) and Aegilops speltoides (Feldman and Mello-Sampayo 1967 ; Riley et al 1961 ; Li et al 2017 and ref therein), which suppress Ph1 . The promotion of COs between homoeologues can be obtained either directly in F1 hybrids (King et al 2017 ) or after the suppressor of Ph1 has been introgressed into wheat.…”

“…The second approach is more versatile, but longer and more difficult to implement. Recently, Li et al ( 2017 ) used marker-assisted selection to introgress a dominant suppressor of Ph1 ( Su1 - Ph1 ) from Aegilops speltoides into hexaploid and tetraploid wheat. Although the presence of the introgression suppressed Ph1 activity in the tetraploid background, this was not the case in hexaploid wheat.…”

Developing New Oligo Probes to Distinguish Specific Chromosomal Segments and the A, B, D Genomes of Wheat (Triticum aestivum L.) Using ND-FISH

“…ND-FISH technology has provided a convenient and efficient way to identify the chromosomes of Triticeae species ( Cuadrado and Jouve, 2010 ; Carmona et al, 2013 ; Carvalho et al, 2013 ; Cuadrado et al, 2013 ; Cabo et al, 2014 ; Tang et al, 2014 ; Fu et al, 2015 ; Delgado et al, 2016 , 2017 ; Li et al, 2016 ; Li J. et al, 2017 ; Li H. et al, 2017 ; Du et al, 2017 ; Duan et al, 2017 ; Jiang et al, 2017 ; Xiao et al, 2017 ). The key step for a successful ND-FISH analysis is to obtaining suitable oligo probes.…”

“…Simple sequence repeat and non-SSR oligo probes such as (AAG) n , (AAC) n , Oligo-pSc119.2, Oligo-pTa535, Oligo-pTa71, Oligo-s120, Oligo-275, Oligo-k566, and Oligo-713 have already been used to identify individual wheat chromosome ( Cuadrado and Schwarzacher, 1998 ; Cuadrado et al, 2000 ; Carvalho et al, 2013 ; Mirzaghaderi et al, 2014 ; Tang et al, 2014 , 2016 ; Fu et al, 2015 ; Zhang et al, 2015 ; Li et al, 2016 ; Li J. et al, 2017 ; Li H. et al, 2017 ; Yang et al, 2016 ; Zhao et al, 2016 , 2018 ; Delgado et al, 2017 ; Du et al, 2017 ; Duan et al, 2017 ; Jiang et al, 2017 ; Xiao et al, 2017 ). However, these oligo probes produce their signals on several wheat chromosomes and they are not chromosome-specific or chromosome segment-specific.…”

The Effect of Chromosome Structure upon Meiotic Homologous and Homoeologous Recombinations in Triticeae

“…One of the two major suppressor loci of Ae. speltoides, Su1-Ph1, which is located distally on the long arm of chromosome 3S, has been introgressed into chromosome 3A of hexaploid and tetraploid wheats [133] and can be used in interspecific gene transfer.…”