Skip to main content

B chromosomes in rye

Genetic study solves the mystery of 'selfish' B chromosomes in rye


Some chromosomes, such as B chromosomes, can increase their inheritance rate to their own advantage. These extra chromosomes are found in many plants, animals, and fungi and rely upon various strategies to avoid being eliminated over time, as most organisms tend to remove non-essential genetic elements.

However, the genetic mechanisms by which B chromosomes avoid elimination are poorly understood. An international research team led by IPK Leibniz Institute identified genes on the rye B chromosome, that are likely responsible for regulating this process. The results were published in Nature Communications.

Supernumerary B chromosomes, unlike A (standard) chromosomes, are not required for the normal growth and development of organisms and as of 2024, B chromosomes have been discovered in almost 3,000 species from all eukaryotic phyla. Most B chromosomes confer no detectable selective consequences at low numbers, but increased numbers can result in phenotypic aberrations and reduced fertility.

To avoid elimination, many B chromosomes influence cell division in their favor and increase their copy number in the process. This phenomenon is called chromosome drive. The "selfish" B chromosomes, therefore, only become active when their existence is at stake and not for the benefit of the plant.

Drive mechanisms in B chromosome systems have been studied in many species and contexts using various technologies, from classical genetics to cytogenetics.

But despite being an ideal test case to study the underlying mechanisms of the chromosome drive, B chromosome research has only slowly been able to capitalize on the data explosion of the DNA sequencing boom. B chromosomes are highly structurally complex, repetitive, and multitudinous, all of which make them resistant to pseudomolecule-level chromosome assembly, especially before recent developments in the area of long-read sequencing.

As such, gene-level insight into the specific mechanisms that control chromosome drive is severely limited, and specific gene candidates implicated in this phenomenon have not been identified so far.

To identify drive-controlling factor(s) on the rye B chromosome, an international research team led by the IPK Leibniz Institute first narrowed down the size of the drive-control region.

Next, the researchers used long DNA reads and assembled the rye B chromosome into a single ~430 Mb-long pseudomolecule and performed a detailed transcriptome analysis.

"Using a newly-assembled B chromosome pseudomolecule, we identified five candidate genes whose role as moderators of chromosome drive is supported by additional studies," explains Jianyong Chen, first author of the study.

"The DCR28 gene, which is presumably responsible for regulating this process, stood out," emphasizes Prof. Andreas Houben, head of IPK's research group "Chromosome Structure and Function." Furthermore, it was shown that the B chromosome originated from fragments of all seven rye standard A chromosomes.

These findings could also be helpful for research into genetic diseases that are based on the unequal distribution of chromosomes.

genetic diversity, chromosomal variation, rye genome, B chromosomes, supernumerary chromosomes, gene expression, genome instability, chromosomal inheritance, non-Mendelian inheritance, chromosomal drive, adaptive evolution, chromatin structure, cytogenetics, nucleolar organizing regions, gene silencing, molecular markers, DNA amplification, heterochromatin, karyotype evolution, plant genetics,

#Genetics #BChromosomes #ChromosomeVariation #RyeGenomics #SupernumeraryChromosomes #GeneExpression #GenomeInstability #NonMendelian #ChromosomalInheritance #EvolutionaryBiology #PlantGenetics #Cytogenetics #GeneSilencing #AdaptiveEvolution #MolecularMarkers #ChromatinStructure #Heterochromatin #Karyotype #NucleolarOrganization #Rye

Comments

Post a Comment

Popular posts from this blog

Fruitful innovation

Fruitful innovation: Transforming watermelon genetics with advanced base editors The development of new adenine base editors (ABE) and adenine-to-thymine/ guanine base editors (AKBE) is transforming watermelon genetic engineering. These innovative tools enable precise A:T-to-G and A:T-to-T base substitutions, allowing for targeted genetic modifications. The research highlights the efficiency of these editors in generating specific mutations, such as a flowerless phenotype in ClFT (Y84H) mutant plants. This advancement not only enhances the understanding of gene function but also significantly improves molecular breeding, paving the way for more efficient watermelon crop improvement. Traditional breeding methods for watermelon often face challenges in achieving desired genetic traits efficiently and accurately. While CRISPR/Cas9 has provided a powerful tool for genome editing, its precision and scope are sometimes limited. These limitations highlight the need for more advanced gene-e...
Post a Comment
Read more

Genetic factors with clinical trial stoppage

Genetic factors associated with reasons for clinical trial stoppage Many drug discovery projects are started but few progress fully through clinical trials to approval. Previous work has shown that human genetics support for the therapeutic hypothesis increases the chance of trial progression. Here, we applied natural language processing to classify the free-text reasons for 28,561 clinical trials that stopped before their endpoints were met. We then evaluated these classes in light of the underlying evidence for the therapeutic hypothesis and target properties. We found that trials are more likely to stop because of a lack of efficacy in the absence of strong genetic evidence from human populations or genetically modified animal models. Furthermore, certain trials are more likely to stop for safety reasons if the drug target gene is highly constrained in human populations and if the gene is broadly expressed across tissues. These results support the growing use of human genetics to ...
Post a Comment
Read more

Genetics study on COVID-19

Large genetic study on severe COVID-19 Bonn researchers confirm three other genes for increased risk in addition to the known TLR7 gene Whether or not a person becomes seriously ill with COVID-19 depends, among other things, on genetic factors. With this in mind, researchers from the University Hospital Bonn (UKB) and the University of Bonn, in cooperation with other research teams from Germany, the Netherlands, Spain and Italy, investigated a particularly large group of affected individuals. They confirmed the central and already known role of the TLR7 gene in severe courses of the disease in men, but were also able to find evidence for a contribution of the gene in women. In addition, they were able to show that genetic changes in three other genes of the innate immune system contribute to severe COVID-19. The results have now been published in the journal " Human Genetics and Genomics Advances ". Even though the number of severe cases following infection with the SARS-CoV-...
Post a Comment
Read more