The wheat wild relative
Central to the diversity of wheat products was the origin of hexaploid bread wheat, which added the D-genome of
- PAR ID:
- 10306539
- Author(s) / Creator(s):
- ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; more »
- Publisher / Repository:
- Nature Publishing Group
- Date Published:
- Journal Name:
- Communications Biology
- Volume:
- 4
- Issue:
- 1
- ISSN:
- 2399-3642
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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Abstract Aegilops tauschii was previously used to transfer theLr42 leaf rust resistance gene into bread wheat.Lr42 confers resistance at both seedling and adult stages, and it is broadly effective against all leaf rust races tested to date.Lr42 has been used extensively in the CIMMYT international wheat breeding program with resulting cultivars deployed in several countries. Here, using a bulked segregant RNA-Seq (BSR-Seq) mapping strategy, we identify three candidate genes forLr42 . Overexpression of a nucleotide-binding site leucine-rich repeat (NLR) gene AET1Gv20040300 induces strong resistance to leaf rust in wheat and a mutation of the gene disrupted the resistance. TheLr42 resistance allele is rare inAe. tauschii and likely arose from ectopic recombination. Cloning ofLr42 provides diagnostic markers and over 1000 CIMMYT wheat lines carryingLr42 have been developed documenting its widespread use and impact in crop improvement. -
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SUMMARY Aegilops species represent the most important gene pool for breeding bread wheat (Triticum aestivum ). Thus, understanding the genome evolution, including chromosomal structural rearrangements and syntenic relationships amongAegilops species or betweenAegilops and wheat, is important for both basic genome research and practical breeding applications. In the present study, we attempted to develop subgenome D‐specific fluorescencein situ hybridization (FISH) probes by selecting D‐specific oligonucleotides based on the reference genome of Chinese Spring. The oligo‐based chromosome painting probes consisted of approximately 26 000 oligos per chromosome and their specificity was confirmed in both diploid and polyploid species containing the D subgenome. Two previously reported translocations involving two D chromosomes have been confirmed in wheat varieties and their derived lines. We demonstrate that the oligo painting probes can be used not only to identify the translocations involving D subgenome chromosomes, but also to determine the precise positions of chromosomal breakpoints. Chromosome painting of 56 accessions ofAe. tauschii from different origins led us to identify two novel translocations: a reciprocal 3D‐7D translocation in two accessions and a complex 4D‐5D‐7D translocation in one accession. Painting probes were also used to analyze chromosomes from more diverseAegilops species. These probes produced FISH signals in four different genomes. Chromosome rearrangements were identified inAegilops umbellulata ,Aegilops markgrafii , andAegilops uniaristata , thus providing syntenic information that will be valuable for the application of these wild species in wheat breeding. -
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Abstract Polyploidy complicates transcriptional regulation and increases phenotypic diversity in organisms. The dynamics of genetic regulation of gene expression between coresident subgenomes in polyploids remains to be understood. Here we document the genetic regulation of fiber development in allotetraploid cotton
Gossypium hirsutum by sequencing 376 genomes and 2,215 time-series transcriptomes. We characterize 1,258 genes comprising 36 genetic modules that control staged fiber development and uncover genetic components governing their partitioned expression relative to subgenomic duplicated genes (homoeologs). Only about 30% of fiber quality-related homoeologs show phenotypically favorable allele aggregation in cultivars, highlighting the potential for subgenome additivity in fiber improvement. We envision a genome-enabled breeding strategy, with particular attention to 48 favorable alleles related to fiber phenotypes that have been subjected to purifying selection during domestication. Our work delineates the dynamics of gene regulation during fiber development and highlights the potential of subgenomic coordination underpinning phenotypes in polyploid plants. -
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Abstract Phenotypic variation within a species is often structured geographically in clines. In
Drosophila americana , a longitudinal cline for body colour exists within North America that appears to be due to local adaptation. Thetan andebony genes have been hypothesized to contribute to this cline, with alleles of both genes that lighten body colour found inD. americana . These alleles are similar in sequence and function to the allele fixed inD. americana's more lightly pigmented sister species,Drosophila novamexicana . Here, we examine the frequency and geographic distribution of theseD. novamexicana ‐like alleles inD. americana . Among alleles from over 100 strains ofD. americana isolated from 21 geographic locations, we failed to identify additional alleles oftan orebony with as much sequence similarity toD. novamexicana as theD. novamexicana ‐like alleles previously described. However, using genetic analysis of 51D. americana strains derived from 20 geographic locations, we identified one new allele ofebony and one new allele oftan segregating inD. americana that are functionally equivalent to theD. novamexicana allele. An additional 5 alleles oftan also showed marginal evidence of functional similarity. Given the rarity of these alleles, however, we conclude that they are unlikely to be driving the pigmentation cline. Indeed, phenotypic distributions of the 51 backcross populations analysed indicate a more complex genetic architecture, with diversity in the number and effects of loci altering pigmentation observed both within and among populations ofD. americana . This genetic heterogeneity poses a challenge to association studies and genomic scans for clinal variation, but might be common in natural populations. -
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Abstract Hessian fly (HF;
Mayetiola destructor Say) causes severe damage to wheat (Triticum aestivum L.) worldwide. Several resistance genes have been identified in wheat and wild relatives; however, HF populations are under strong selection pressure and evolve rapidly to overcome resistance. To ensure the availability of resistance sources, HF‐resistant germplasm KS18WGRC65 (TA5110, Reg. no. GP‐1042, PI 688251) was developed by Wheat Genetics Resource Center at Kansas State University as a breeding stock that carries resistance geneH26 fromAegilops tauschii Coss. KS18WGRC65 is a cytogenetically stable, homozygous, BC3F3:6line derived from the cross betweenAe. tauschii accession KU2147 and hard red winter wheat recurrent parent ‘Overley’. KS18WGRC65 exhibited no penalty for yield or other agronomic characters, making it a suitable source of HF resistance for wheat breeding.
