Goatgrasses with U- and M-genomes are important sources of new alleles for wheat breeding to maintain yield and quality under extreme conditions. However, the introgression of beneficial traits from wild Aegilops species into wheat has been limited by poor knowledge of their genomes and scarcity of molecular tools. Here, we present the first linkage map of allotetraploid Aegilops biuncialis Vis., developed using 224 F2 individuals derived from a cross between MvGB382 and MvGB642 accessions. The map comprises 5663 DArTseq markers assigned to 15 linkage groups corresponding to 13 chromosomes. Chromosome 1Mb could not be constructed due to a lack of recombination caused by rearrangements in the MvGB382 accession. The genetic map spans 2518 cM with an average marker density of 2.79 cM. The skeleton map contains 920 segregating markers, divided between the Mb sub-genome (425 markers) and the Ub sub-genome (495 markers). Chromosomes of the Mb sub-genome, originating from Aegilops comosa Sm. in Sibth. et Sm., show well-preserved collinearity with Triticum aestivum L. chromosomes. In contrast, chromosomes of the Ub sub-genome, originating from Aegilops umbellulata Zhuk., exhibit a varying degree of collinearity, with 1Ub, 3Ub, and 5Ub retaining a substantial level of collinearity with Triticum aestivum, while 2Ub, 4Ub, 6Ub, and 7Ub show significant rearrangements. A quantitative trait locus affecting fertility was identified near the centromere on the long arm of chromosome 3Mb, explaining 23.5% of the variance. The genome structure of Aegilops biuncialis, highlighted by the genetic map, provides insights into the speciation within the species and will support alien gene transfer into wheat.
GBS read coverage analysis identified a Robertsonian chromosome from two Thinopyrum subgenomes in wheat, conferring leaf and stripe rust resistance, drought tolerance, and maintaining yield stability. Agropyron glael (GLAEL), a Thinopyrum intermedium × Th. ponticum hybrid, serves as a valuable genetic resource for wheat improvement. Despite its potential, limited knowledge of its chromosome structure and homoeologous relationships with hexaploid wheat (Triticum aestivum) has restricted the full exploitation of GLAEL's genetic diversity in breeding programs. Here, we present the development of a 44-chromosome wheat/GLAEL addition line (GLA7). Multicolor genomic in situ hybridization identified one chromosome arm from the St subgenome of Th. intermedium, while the other arm remained unclassified. Genotyping-by-sequencing (GBS) read coverage analysis revealed a unique Robertsonian translocation between two distinct Thinopyrum subgenomes, identified as 4StS·1JvsS. The GLA7 line demonstrated strong adult plant resistance to both leaf rust and stripe rust under natural and artificial infection conditions. Automated phenotyping of shoot morphological parameters together with leaf relative water content and yield components showed that the GLA7 line exhibited elevated drought tolerance compared to parental wheat genotypes. Three years of field trials showed that GLA7 exhibits similar agronomic performance and yield components to the wheat parents. This unique addition line holds promise for enhancing wheat's tolerance to multiple stresses through the introduction of new resistance genes, as well as its ability to mitigate the effects of temporary water limitation during flowering, all without negatively impacting wheat performance.
- MeSH
- Agropyron genetika MeSH
- chromozomy rostlin * genetika MeSH
- fenotyp MeSH
- fyziologický stres * genetika MeSH
- genotyp MeSH
- genotypizační techniky MeSH
- nemoci rostlin * mikrobiologie genetika MeSH
- období sucha MeSH
- odolnost vůči nemocem * genetika MeSH
- pšenice * genetika mikrobiologie růst a vývoj MeSH
- šlechtění rostlin MeSH
- translokace genetická * MeSH
- Publikační typ
- časopisecké články MeSH
The genomes of many plants, animals, and fungi frequently comprise dispensable B chromosomes that rely upon various chromosomal drive mechanisms to counteract the tendency of non-essential genetic elements to be purged over time. The B chromosome of rye - a model system for nearly a century - undergoes targeted nondisjunction during first pollen mitosis, favouring segregation into the generative nucleus, thus increasing their numbers over generations. However, the genetic mechanisms underlying this process are poorly understood. Here, using a newly-assembled, ~430 Mb-long rye B chromosome pseudomolecule, we identify five candidate genes whose role as trans-acting moderators of the chromosomal drive is supported by karyotyping, chromosome drive analysis and comparative RNA-seq. Among them, we identify DCR28, coding a microtubule-associated protein related to cell division, and detect this gene also in the B chromosome of Aegilops speltoides. The DCR28 gene family is neo-functionalised and serially-duplicated with 15 B chromosome-located copies that are uniquely highly expressed in the first pollen mitosis of rye.
- MeSH
- Aegilops genetika metabolismus MeSH
- chromozomy rostlin * genetika MeSH
- karyotypizace MeSH
- mitóza * genetika MeSH
- nondisjunkce genetická MeSH
- pyl genetika MeSH
- regulace genové exprese u rostlin MeSH
- rostlinné geny MeSH
- rostlinné proteiny genetika metabolismus MeSH
- žito * genetika MeSH
- Publikační typ
- časopisecké články MeSH
- Názvy látek
- rostlinné proteiny MeSH
The B chromosomes exhibit diverse behaviour compared with conventional genetic models. The capacity of the B chromosome either to accumulate or to be eliminated in a tissue-specific manner is dependent on biological processes related to aberrant cell division(s), but here yet remains compatible with normal development. We studied B chromosome elimination in Sorghum purpureosericeum embryos through cryo-sections and demonstrated the B chromosome instability during plant growth using flow cytometry, molecular markers and fluorescent in situ hybridization techniques. Consequently, using B chromosome-specific probes we revealed the non-Mendelian inheritance of B chromosomes in developing pollen. We disclosed that the occurrence of the B chromosome is specific to certain tissues or organs. The distribution pattern is mainly caused by an extensive elimination that functions primarily during embryo development and persists throughout plant development. Furthermore, we described that B chromosome accumulation can occur either by nondisjunction at first pollen mitosis (PMI) or the initiation of extra nuclear division(s) during pollen development. Our study demonstrates the existence of a not-yet-fully described B chromosome drive process, which is likely under the control of the B chromosome.
- Klíčová slova
- B chromosome, accumulation mechanism, chromosome drive, chromosome elimination, extra pollen mitosis, nondisjunction, pollen mitosis, polymitosis,
- MeSH
- chromozomy rostlin * genetika MeSH
- mitóza * MeSH
- nondisjunkce genetická * MeSH
- pyl * genetika cytologie MeSH
- semena rostlinná genetika růst a vývoj MeSH
- Sorghum * genetika MeSH
- Publikační typ
- časopisecké články MeSH
Restoring cytonuclear stoichiometry is necessary after whole-genome duplication (WGD) and interspecific/intergeneric hybridization in plants. We investigated this phenomenon in auto- and allopolyploids of the Festuca-Lolium complex providing insights into the mechanisms governing cytonuclear interactions in early polyploid and hybrid generations. Our study examined the main processes potentially involved in restoring the cytonuclear balance after WGD comparing diploids and new and well-established autopolyploids. We uncovered that both the number of chloroplasts and the number of chloroplast genome copies were significantly higher in the newly established autopolyploids and grew further in more established autopolyploids. The increase in the copy number of the chloroplast genome exceeded the rise in the number of chloroplasts and fully compensated for the doubling of the nuclear genome. In addition, changes in nuclear and organelle gene expression were insignificant. Allopolyploid Festuca × Lolium hybrids displayed potential structural conflicts in parental protein variants within the cytonuclear complexes. While biased maternal allele expression has been observed in numerous hybrids, our results suggest that its role in cytonuclear stabilization in the Festuca × Lolium hybrids is limited. This study provides insights into the restoration of the cytonuclear stoichiometry, yet it emphasizes the need for future research to explore post-transcriptional regulation and its impact on cytonuclear gene expression stoichiometry. Our findings may enhance the understanding of polyploid plant evolution, with broader implications for the study of cytonuclear interactions in diverse biological contexts.
- Klíčová slova
- Festuca pratensis Huds., Lolium multiflorum lam., allopolyploidy, autopolyploidy, chloroplast, cytonuclear interactions, gene expression, organelle DNA, protein modeling, whole genome duplication,
- MeSH
- buněčné jádro * genetika metabolismus MeSH
- chloroplasty genetika metabolismus MeSH
- Festuca * genetika MeSH
- genom chloroplastový MeSH
- genom rostlinný genetika MeSH
- hybridizace genetická MeSH
- jílek * genetika MeSH
- polyploidie * MeSH
- regulace genové exprese u rostlin MeSH
- Publikační typ
- časopisecké články MeSH
Some species of the genus Aegilops, a wild relative of wheat, carry chromosomes that after introducing to wheat exhibit preferential transmission to progeny. Their selective retention is a result of the abortion of gametes lacking them due to induced chromosomal aberrations. These chromosomes are termed Gametocidal (Gc) and, based on their effects, they are categorized into three types: mild, intense or severe, and very strong. Gc elements within the same homoeologous chromosome groups of Aegilops (II, III, or IV) demonstrate similar Gc action. This review explores the intriguing dynamics of Gc chromosomes and encompasses comprehensive insights into their source species, behavioral aspects, mode of action, interactions, suppressions, and practical applications of the Gc system in wheat breeding. By delving into these areas, this work aims to contribute to the development of novel plant genetic resources for wheat breeding. The insights provided herein shed light on the utilization of Gc chromosomes to produce chromosomal rearrangements in wheat and its wild relatives, thereby facilitating the generation of chromosome deletions, translocations, and telosomic lines. The Gc approach has significantly advanced various aspects of wheat genetics, including the introgression of novel genes and alleles, molecular markers and gene mapping, and the exploration of homoeologous relationships within Triticeae species. The mystery lies in why gametes possessing Gc genes maintain their normality while those lacking Gc genes suffer abnormalities, highlighting an unresolved research gap necessitating deeper investigation.
- Klíčová slova
- Aegilops, Gc factors/elements/genes, Triticum, gametocidal, pollen-killer, segregation distorter, wheat,
- Publikační typ
- časopisecké články MeSH
- přehledy MeSH
The annual goatgrass, Aegilops biuncialis is a rich source of genes with considerable agronomic value. This genetic potential can be exploited for wheat improvement through interspecific hybridization to increase stress resistance, grain quality and adaptability. However, the low throughput of cytogenetic selection hampers the development of alien introgressions. Using the sequence of flow-sorted chromosomes of diploid progenitors, the present study enabled the development of chromosome-specific markers. In total, 482 PCR markers were validated on wheat (Mv9kr1) and Ae. biuncialis (MvGB642) crossing partners, and 126 on wheat-Aegilops additions. Thirty-two markers specific for U- or M-chromosomes were used in combination with GISH and FISH for the screening of 44 Mv9kr1 × Ae. biuncialis BC3F3 genotypes. The predominance of chromosomes 4M and 5M, as well as the presence of chromosomal aberrations, may indicate that these chromosomes have a gametocidal effect. A new wheat-Ae. biuncialis disomic 4U addition, 4M(4D) and 5M(5D) substitutions, as well as several introgression lines were selected. Spike morphology and fertility indicated that the Aegilops 4M or 5M compensated well for the loss of 4D and 5D, respectively. The new cytogenetic stocks represent valuable genetic resources for the introgression of key genes alleles into wheat.
In sweet cherry (Prunus avium L.), quantitative trait loci have been identified for fruit maturity, colour, firmness, and size to develop markers for marker-assisted selection. However, resolution is usually too low in those analyses to directly target candidate genes, and some associations are missed. In contrast, genome-wide association studies are performed on broad collections of accessions, and assemblies of reference sequences from Tieton and Satonishiki cultivars enable identification of single nucleotide polymorphisms after whole-genome sequencing, providing high marker density. Two hundred and thirty-five sweet cherry accessions were sequenced and phenotyped for harvest time and fruit colour, firmness, and size. Genome-wide association studies were used to identify single nucleotide polymorphisms associated with each trait, which were verified in breeding material consisting of 64 additional accessions. A total of 1 767 106 single nucleotide polymorphisms were identified. At that density, significant single nucleotide polymorphisms could be linked to co-inherited haplotype blocks (median size ~10 kb). Thus, markers were tightly associated with respective phenotypes, and individual allelic combinations of particular single nucleotide polymorphisms provided links to distinct phenotypes. In addition, yellow-fruit accessions were sequenced, and a ~ 90-kb-deletion on chromosome 3 that included five MYB10 transcription factors was associated with the phenotype. Overall, the study confirmed numerous quantitative trait loci from bi-parental populations using high-diversity accession populations, identified novel associations, and genome-wide association studies reduced the size of trait-associated loci from megabases to kilobases and to a few candidate genes per locus. Thus, a framework is provided to develop molecular markers and evaluate and characterize genes underlying important agronomic traits.
- Publikační typ
- časopisecké články MeSH
Leaf rust, caused by Puccinia hordei, is one of the most widespread and damaging foliar diseases affecting barley. The barley leaf rust resistance locus Rph7 has been shown to have unusually high sequence and haplotype divergence. In this study, we isolate the Rph7 gene using a fine mapping and RNA-Seq approach that is confirmed by mutational analysis and transgenic complementation. Rph7 is a pathogen-induced, non-canonical resistance gene encoding a protein that is distinct from other known plant disease resistance proteins in the Triticeae. Structural analysis using an AlphaFold2 protein model suggests that Rph7 encodes a putative NAC transcription factor with a zinc-finger BED domain with structural similarity to the N-terminal DNA-binding domain of the NAC transcription factor (ANAC019) from Arabidopsis. A global gene expression analysis suggests Rph7 mediates the activation and strength of the basal defence response. The isolation of Rph7 highlights the diversification of resistance mechanisms available for engineering disease control in crops.
- MeSH
- Arabidopsis * genetika MeSH
- Basidiomycota * MeSH
- ekzém * MeSH
- ječmen (rod) * genetika MeSH
- lipnicovité MeSH
- nemoci rostlin genetika MeSH
- regulace genové exprese MeSH
- rostlinné proteiny genetika MeSH
- transkripční faktory genetika MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- Názvy látek
- rostlinné proteiny MeSH
- transkripční faktory MeSH
To safeguard bread wheat against pests and diseases, breeders have introduced over 200 resistance genes into its genome, thus nearly doubling the number of designated resistance genes in the wheat gene pool1. Isolating these genes facilitates their fast-tracking in breeding programs and incorporation into polygene stacks for more durable resistance. We cloned the stem rust resistance gene Sr43, which was crossed into bread wheat from the wild grass Thinopyrum elongatum2,3. Sr43 encodes an active protein kinase fused to two domains of unknown function. The gene, which is unique to the Triticeae, appears to have arisen through a gene fusion event 6.7 to 11.6 million years ago. Transgenic expression of Sr43 in wheat conferred high levels of resistance to a wide range of isolates of the pathogen causing stem rust, highlighting the potential value of Sr43 in resistance breeding and engineering.
