QTug.sau-3B Is a Major Quantitative Trait Locus for Wheat Hexaploidization

Abstract

Meiotic nonreduction resulting in unreduced gametes is thought to be the predominant mechanism underlying allopolyploid formation in plants. Until now, however, its genetic base was largely unknown. The allohexaploid crop common wheat (Triticum aestivum L.), which originated from hybrids of T. turgidum L. with Aegilops tauschii Cosson, provides a model to address this issue. Our observations of meiosis in pollen mother cells from T. turgidum×Ae. tauschii hybrids indicated that first division restitution, which exhibited prolonged cell division during meiosis I, was responsible for unreduced gamete formation. A major quantitative trait locus (QTL) for this trait, named QTug.sau-3B, was detected on chromosome 3B in two T. turgidum×Ae. tauschii haploid populations. This QTL is situated between markers Xgwm285 and Xcfp1012 and covered a genetic distance of 1 cM in one population. QTug.sau-3B is a haploid-dependent QTL because it was not detected in doubled haploid populations. Comparative genome analysis indicated that this QTL was close to Ttam-3B, a collinear homolog of tam in wheat. Although the relationship between QTug.sau-3B and Ttam requires further study, high frequencies of unreduced gametes may be related to reduced expression of Ttam in wheat.

Sister chromatid separation and monopolar spindle organization in the first meiosis as two mechanisms of unreduced gametes formation in wheat–rye hybrids

“…It was shown previously that unreduced gametes produced in interspecific/intergeneric hybrids of bread wheat are controlled by the genetic make-up of the parental species (Wagenaar 1968 ; Xu and Joppa 1995 ; Matsuoka and Nasuda 2004 ; Zhang et al 2007 , 2008 ; Matsuoka et al 2013 ; Hao et al 2014 ). For instance, T. turgidum var.…”

“…tauschii Coss. (Matsuoka and Nasuda 2004 ; Zhang et al 2007 , 2008 ; Hao et al 2014 ). This division type was designated as the single division of meiosis (SDM) (Matsuoka and Nasuda 2004 ).…”

“…This division type was designated as the single division of meiosis (SDM) (Matsuoka and Nasuda 2004 ). Data by Hao et al ( 2014 ) and Zhang et al ( 2007 , 2008 ) showed that both FDR and SDM can result in the formation of functional unreduced gametes in T. turgidum × Ae. tauschii hybrids.…”

“…The first cytological studies of the mechanisms underlying the formation of unreduced gametes in intergeneric wheat hybrids ( T. turgidum , T. aestivum ) date back to 1930s and are still actively pursued (review Silkova et al 2011a ; Matsuoka et al 2013 ; Hao et al 2014 ). Considerable research focused on the understanding of cytogenetic mechanisms underlying the formation of the extant bread wheat genome (Xu and Joppa 1995 ; Matsuoka and Nasuda 2004 ; Zhang et al 2007 ; Cai et al 2010 ; Matsuoka et al 2013 ; Hao et al 2014 ). Chromosome non-disjunction during the first meiotic division (the restitution nucleus forming) is the cytological mechanisms behind the formation of unreduced gametes in triploid F 1 hybrids between the direct ancestors of allohexaploid bread wheat ( T. aestivum L., AABBDD genome), T. turgidum L. (AABB genome) and Aegilops tauschii Coss.…”

A transcriptomic view of the ability of nascent hexaploid wheat to tolerate aneuploidy

“…The oligonucleotide probes Oligo-pSc119.2 and Oligo-pTa535 were synthesized by TSINGKE Biological Technology Company (Beijing, China) and were 5′ end labelled with either TAMRA or 6-FAM. Genomic in situ hybridization (GISH) experiments were performed as described by Hao et al [41]. To distinguish between the chromosome complements of each of the three wheat subgenomes, total genomic DNA extracted from the A genome donor Triticum urartu and the D genome donor Ae.…”