Biology subjects

Lempe, J.

Publications and source records attributed to Lempe, J..

3 recordsLinked to original sources

bioRxiv2023

Decreasing LTP2 expression increases phenotypic variation in early seedling traits of Arabidopsis thaliana

Isogenic individuals can display seemingly stochastic phenotypic differences, limiting the accuracy of genotype-to-phenotype predictions. The extent of this phenotypic variation depends in part on genetic background, raising questions about the genes involved in controlling stochastic phenotypic variation. Focusing on early seedling traits in Arabidopsis thaliana, we found that hypomorphs of the cuticle-related gene LTP2 greatly increased variation in seedling phenotypes, including hypocotyl length, gravitropism and cuticle permeability. Many ltp2 hypocotyls were significantly shorter than wild-type hypocotyls while others resembled the wild type. Differences in epidermal properties and gene expression between ltp2 seedlings with long and short hypocotyls suggest a loss of cuticle integrity as the primary determinant of the observed phenotypic variation. We identified environmental conditions that reveal or mask the increased variation in ltp2 hypomorphs, and found that increased expression of its closest paralog LTP1 is necessary for ltp2 phenotypes. Our results illustrate how decreased expression of a single gene can generate starkly increased phenotypic variation in isogenic individuals in response to an environmental challenge.

plant biology↗

bioRxiv2023

The structure of the tetraploid sour cherry 'Schattenmorelle' (Prunus cerasus L.) genome reveals insights into its segmental allopolyploid nature

Sour cherry (Prunus cerasus L.) is an economically important allotetraploid cherry species believed to have evolved in the Caspian Sea and Black Sea regions. How, when and where exactly the evolution of this species took place is unclear. It resulted from a hybridization of the tetraploid ground cherry (Prunus fruticosa Pall.) and an unreduced (2n) pollen of the diploid ancestor sweet cherry (P. avium L.). Some indications implement that the genome of sour cherry is segmental allopolyploid, but how it is structured and to what extent is unknown. To get an insight, the genome of the sour cherry cultivar Schattenmorelle was sequenced at ~400x using Illumina NovaSeqTM short-read and Oxford Nanopore long-read technologies (ONT R9.4.1 PromethION). Additionally, the transcriptome of Schattenmorelle was sequenced using PacBio Sequel II SMRT cell sequencing at ~300x. The final assembly resulted in a ~629 Mbp long pseudomolecule reference genome, which could be separated into two subgenomes each split into eight chromosomes. Subgenome PceS_a which originates from P. avium has a length of 269 Mbp, whereas subgenome PceS_f which originates from P. fruticosa has a length of 299.5 Mbp. The length of unassembled contigs was 60 Mbp. The genome of the sour cherry shows a size-reduction compared to the genomes of its ancestral species. It also shows traces of homoeologous sequence exchanges throughout the genome. Comparative positional sequence and protein analyses provided evidence that the genome of sour cherry is segmental allotetraploid and that it has evolved in a very recent event in the past.

genomics↗

bioRxiv2016

Genomic Rearrangements Considered as Quantitative Traits

To understand the population genetics of structural variants (SVs), and their effects on phenotypes, we developed an approach to mapping SVs, particularly transpositions, segregating in a sequenced population, and which avoids calling SVs directly. The evidence for a potential SV at a locus is indicated by variation in the counts of short-reads that map anomalously to the locus. These SV traits are treated as quantitative traits and mapped genetically, analogously to a gene expression study. Association between an SV trait at one locus and genotypes at a distant locus indicate the origin and target of a transposition. Using ultra-low-coverage (0.3x) population sequence data from 488 recombinant inbred Arabidopsis genomes, we identified 6,502 segregating SVs. Remarkably, 25% of these were transpositions. Whilst many SVs cannot be delineated precisely, PCR validated 83% of 44 predicted transposition breakpoints. We show that specific SVs may be causative for quantitative trait loci for germination, fungal disease resistance and other phenotypes. Further we show that the phenotypic heritability attributable to sequence anomalies differs from, and in the case of time to germination and bolting, exceeds that due to standard genetic variation. Gene expression within SVs is also more likely to be silenced or dysregulated. This approach is generally applicable to large populations sequenced at low-coverage, and complements the prevalent strategy of SV discovery in fewer individuals sequenced at high coverage.

genetics↗