Biology subjects

Dorussen, D.

Publications and source records attributed to Dorussen, D..

3 recordsLinked to original sources

bioRxiv2024

Partial redundancy buffers deleterious effects of mutating DNA methyltransferase 1-1 (MET1-1) in polyploid wheat

DNA methylation is conserved across biological kingdoms, playing important roles in gene expression, transposable element silencing and genome stability. Altering DNA methylation could generate additional phenotypic variation for crop breeding, however the lethality of epigenetic mutants in crop species has hindered its investigation. Here, we exploit partial redundancy between homoeologs in polyploid wheat to generate viable mutants in the DNA methyltransferase 1-1 (MET1-1) gene with altered methylation profiles. In both Triticum turgidum (tetraploid wheat) and Triticum aestivum (hexaploid wheat) we identified clear segregation distortions of higher-order mutants (5/6 and 6/6 mutant met1-1 copies in hexaploid and 3/4 and 4/4 copies in tetraploid) when genotyping segregating seeds and seedlings, which we attribute to reduced transmission of null mutant gametes. We found that the reduced transmission occurred from both the maternal and paternal gametes, however, we did not detect any deleterious effects on pollen development. The loss of four or more functional copies of MET1-1 results in decreased CG methylation in hexaploid wheat. Changes to gene expression increase stepwise with the number of mutant alleles suggesting a dosage dependent effect. Finally, we identify heritable changes to flowering and awn phenotypes which segregate independently of MET1-1. Together our results demonstrate that polyploidy can be leveraged to generate quantitative changes to CG methylation without the lethal consequences observed in other crops, opening the potential to exploit novel epialleles in plant breeding.

plant biology↗

bioRxiv2024

Species wide inventory of Arabidopsis thaliana organellar variation reveals ample phenotypic variation for photosynthetic performance

Efforts to improve photosynthetic performance are increasingly employing natural genetic variation. However, genetic variation in the organellar genomes (plasmotypes) is often disregarded due to the difficulty of studying the plasmotypes and the lack of evidence that this is a worthwhile investment. Here, we systematically phenotyped plasmotype diversity using Arabidopsis thaliana as a model species. A reanalysis of whole genome resequencing data of 1,531 representative accessions shows that the genetic diversity amongst the mitochondrial genomes is eight times lower than amongst the chloroplast genomes. Plasmotype diversity of the accessions divides the species into two major phylogenetic clusters, within which highly divergent subclusters are distinguished. We combined plasmotypes from 60 A. thaliana accessions with the nuclear genomes (nucleotypes) of four A. thaliana accessions to create a panel of 232 novel cytonuclear genotypes (cybrids). The cybrid plants were grown in a range of different light and temperature conditions and phenotyped using high-throughput phenotyping platforms. Analysis of the phenotypes showed that several plasmotypes alone or in interaction with the nucleotypes have significant effects on photosynthesis, and that the effects are highly dependent on the environment. Moreover, we introduce Plasmotype Association Studies (PAS) as a novel method to reveal plasmotypic effects. Within A. thaliana, several organellar variants can influence photosynthetic phenotypes, which emphasizes the valuable role this variation has on improving photosynthetic performance. The increasing feasibility of producing cybrids in various species calls for further research into how these phenotypes may support breeding goals in crop species. Significance statementPhotosynthesis is one of the few crop traits that has been largely unaddressed which can contribute to increasing crop yield potential. Exploiting genetic variation within organellar genomes presents a promising, yet untapped resource to improve photosynthesis. However, the extent of organellar variation and its impact on photosynthesis within a species remains largely unknown. Using Arabidopsis thaliana as a model species, we revealed highly divergent clusters of organellar variation. We constructed 232 novel combinations of species representative organellar and nuclear genomes, referred to as cybrids. High-throughput phenotyping of these cybrids revealed that organellar variants can substantially impact photosynthesis in different environments. These findings indicate that organellar genomes may be a valuable resource for improving photosynthesis in crops.

plant biology↗

bioRxiv2020

Blocking plasmodesmata in specific phloem cell types reduces axillary bud growth in Arabidopsis thaliana

The plasticity of above ground plant architecture depends on the regulated re-activation and growth of axillary meristems laid down in the axils of leaves along the stem, which often arrest as dormant buds. Plasmodesmata connecting plant cells might control the movement of regulators involved in this developmental switch. Constructs capable of occluding these structures were employed in phloem cell types, because of the importance of phloem in local and systemic trafficking. We show that over-accumulation of callose within companion cells of the Arabidopsis inflorescence reduces the growth rates of activated buds, but does not affect bud activation. Growth rate reductions were not dependent on the phloem-mobile strigolactone receptor, which regulates bud activation. Furthermore, there was no correlation with early bud sugar profiles, which can also affect bud activity and depend on phloem-mediated delivery. It is therefore possible that an as yet unknown mobile signal is involved in modulating branch growth rate.

plant biology↗