Karina Stensland Hornslien

• Hornslien, Karina Stensland; Myking, Ida Velle; Bjerkan, Katrine Nergård; Krabberød, Anders Kristian; Miller, Jason Rafe & Grini, Paul (2026). Parent-of-origin specific allelic expression in outbreeding Arabidopsis arenosa identifies antagonistic parental enrichment in protein degradation pathways. New Phytologist. ISSN 0028-646X. doi: 10.1111/nph.71551. Fulltekst i vitenarkiv
• Bramsiepe, Jonathan; Krabberød, Anders Kristian; Bjerkan, Katrine Nergård; Alling, Renate; Nielsen, Ida & Hornslien, Karina Stensland [Vis alle 9 forfattere av denne artikkelen] (2023). Structural evidence for MADS-box type I family expansion seen in new assemblies of Arabidopsis arenosa and A. lyrata. The Plant Journal. ISSN 0960-7412. 116(3), s. 942–961. doi: 10.1111/tpj.16401. Fulltekst i vitenarkiv Vis sammendrag

  SUMMARY Arabidopsis thaliana diverged from A. arenosa and A. lyrata at least 6 million years ago. The three species differ by genome‐wide polymorphisms and morphological traits. The species are to a high degree reproductively isolated, but hybridization barriers are incomplete. A special type of hybridization barrier is based on the triploid endosperm of the seed, where embryo lethality is caused by endosperm failure to support the developing embryo. The MADS‐box type I family of transcription factors is specifically expressed in the endosperm and has been proposed to play a role in endosperm‐based hybridization barriers. The gene family is well known for its high evolutionary duplication rate, as well as being regulated by genomic imprinting. Here we address MADS‐box type I gene family evolution and the role of type I genes in the context of hybridization. Using two de‐novo assembled and annotated chromosome‐level genomes of A. arenosa and A. lyrata ssp. petraea we analyzed the MADS‐box type I gene family in Arabidopsis to predict orthologs, copy number, and structural genomic variation related to the type I loci. Our findings were compared to gene expression profiles sampled before and after the transition to endosperm cellularization in order to investigate the involvement of MADS‐box type I loci in endosperm‐based hybridization barriers. We observed substantial differences in type‐I expression in the endosperm of A. arenosa and A. lyrata ssp. petraea , suggesting a genetic cause for the endosperm‐based hybridization barrier between A. arenosa and A. lyrata ssp. petraea .

• Ekelenburg, Yuri Stephan van; Hornslien, Karina Stensland; Hautegem, Tom Van; Fendrych, Matyáš; Isterdael, Gert Van & Bjerkan, Katrine Nergård [Vis alle 9 forfattere av denne artikkelen] (2022). Spatial and temporal regulation of parent-of-origin allelic expression in the endosperm. Plant Physiology. ISSN 0032-0889. 191(2), s. 986–1001. doi: 10.1093/plphys/kiac520. Fulltekst i vitenarkiv Vis sammendrag

  Genomic imprinting promotes differential expression of parental alleles in the endosperm of flowering plants and is regulated by epigenetic modification such as DNA methylation and histone tail modifications in chromatin. After fertilization, the endosperm develops through a syncytial stage before it cellularizes and becomes a nutrient source for the growing embryo. Regional compartmentalization has been shown both in early and late endosperm development, and different transcriptional domains suggest divergent spatial and temporal regional functions. The analysis of the role of parent-of-origin allelic expression in the endosperm as a whole and the investigation of domain-specific functions have been hampered by the inaccessibility of the tissue for high-throughput transcriptome analyses and contamination from surrounding tissue. Here, we used fluorescence-activated nuclear sorting (FANS) of nuclear targeted GFP fluorescent genetic markers to capture parental-specific allelic expression from different developmental stages and specific endosperm domains. This approach allowed us to successfully identify differential genomic imprinting with temporal and spatial resolution. We used a systematic approach to report temporal regulation of imprinted genes in the endosperm, as well as region-specific imprinting in endosperm domains. Analysis of our data identified loci that are spatially differentially imprinted in one domain of the endosperm, while biparentally expressed in other domains. These findings suggest that the regulation of genomic imprinting is dynamic and challenge the canonical mechanisms for genomic imprinting.

• Hornslien, Karina Stensland; Miller, Jason Rafe & Grini, Paul Eivind (2019). Regulation of Parent-of-Origin Allelic Expression in the Endosperm. Plant Physiology. ISSN 0032-0889. 180(3), s. 1498–1519. doi: 10.1104/pp.19.00320. Fulltekst i vitenarkiv
• Bjerkan, Katrine; Hornslien, Karina Stensland; Johannessen, Ida Marie; Krabberød, Anders Kristian; Ekelenburg, Yuri Stephan van & Kalantarian, Maryam [Vis alle 11 forfattere av denne artikkelen] (2019). Genetic variation and temperature affects hybrid barriers during interspecific hybridization. The Plant Journal. ISSN 0960-7412. 101, s. 122–140. doi: 10.1111/tpj.14523. Fulltekst i vitenarkiv Vis sammendrag

  Genomic imprinting regulates parent‐specific transcript dosage during seed development and is mainly confined to the endosperm. Elucidation of the function of many imprinted genes has been hampered by the lack of corresponding mutant phenotypes, and the role of imprinting is mainly associated with genome dosage regulation or allocation of resources. Disruption of imprinted genes has also been suggested to mediate endosperm‐based post‐zygotic hybrid barriers depending on genetic variation and gene dosage. Here, we have analyzed the conservation of a clade from the MADS‐box type I class transcription factors in the closely related species Arabidopsis arenosa, A. lyrata, and A. thaliana, and show that AGL36‐like genes are imprinted and maternally expressed in seeds of Arabidopsis species and in hybrid seeds between outbreeding species. In hybridizations between outbreeding and inbreeding species the paternally silenced allele of the AGL36‐like gene is reactivated in the hybrid, demonstrating that also maternally expressed imprinted genes are perturbed during hybridization and that such effects on imprinted genes are specific to the species combination. Furthermore, we also demonstrate a quantitative effect of genetic diversity and temperature on the strength of the post‐zygotic hybridization barrier. Markedly, a small decrease in temperature during seed development increases the survival of hybrid F1 seeds, suggesting that abiotic and genetic parameters play important roles in post‐zygotic species barriers, pointing at evolutionary scenarios favoring such effects.

• Lafon-Placette, Clément; Johannessen, Ida Marie; Hornslien, Karina Stensland; Ali, Mohammad F.; Bjerkan, Katrine & Bramsiepe, Jonathan [Vis alle 11 forfattere av denne artikkelen] (2017). Endosperm-based hybridization barriers explain the pattern of gene flow between Arabidopsis lyrata and Arabidopsis arenosa in Central Europe. Proceedings of the National Academy of Sciences of the United States of America (PNAS). ISSN 0027-8424. 114(6), s. E1027–E1035. doi: 10.1073/pnas.1615123114. Fulltekst i vitenarkiv
• Vie, Ane Kjersti; Najafi, Javad; Liu, Bin; Winge, Per; Butenko, Melinka Alonso & Hornslien, Karina Stensland [Vis alle 10 forfattere av denne artikkelen] (2015). The IDA/IDA-LIKE and PIP/PIP-LIKE gene families in Arabidopsis: Phylogenetic relationship, expression patterns, and transcriptional effect of the PIPL3 peptide. Journal of Experimental Botany. ISSN 0022-0957. 66(17), s. 5351–5365. doi: 10.1093/jxb/erv285. Fulltekst i vitenarkiv Vis sammendrag

  Peptide ligands play crucial roles in the life cycle of plants by modulating the innate immunity against pathogens and regulating growth and developmental processes. One well-studied example is INFLORESCENCE DEFICIENT IN ABSCISSION (IDA), which controls floral organ abscission and lateral root emergence in Arabidopsis thaliana. IDA belongs to a family of five additional IDA-LIKE (IDL) members that have all been suggested to be involved in regulation of Arabidopsis development. Here we present three novel members of the IDL subfamily and show that two of them are strongly and rapidly induced by different biotic and abiotic stresses. Furthermore, we provide data that the recently identified PAMP-INDUCED SECRETED PEPTIDE (PIP) and PIP-LIKE (PIPL) peptides, which show similarity to the IDL and C-TERMINALLY ENCODED PEPTIDE (CEP) peptides, are not only involved in innate immune response in Arabidopsis but are also induced by abiotic stress. Expression patterns of the IDA/IDL and PIP/PIPL genes were analysed using in silico data, qRT-PCR and GUS promoter lines. Transcriptomic responses to PIPL3 peptide treatment suggested a role in regulation of biotic stress responses and cell wall modification.

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• Grini, Paul Eivind; Miller, Jason Rafe & Hornslien, Karina Stensland (2019). Imprinting revisited: Genetic and phenotypic routes to postzygotic hybrid barriers and bridges. Fulltekst i vitenarkiv
• Bjerkan, Katrine; Hornslien, Karina Stensland; Johannessen, Ida Marie; Ekelenburg, Yuri Stephan van; Bramsiepe, Jonathan & Brysting, Anne Krag [Vis alle 7 forfattere av denne artikkelen] (2019). Temperature and genetic variation alter strength of the post-zygotic endosperm based barrier between A. thaliana and A.arenosa. Fulltekst i vitenarkiv
• Grini, Paul Eivind; Hornslien, Karina Stensland & Miller, Jason Rafe (2018). Imprinting Revisited: Regulation of Parent-of-Origin Allelic Expression in Arabidopsis thaliana endosperm. Fulltekst i vitenarkiv
• Johannessen, Ida Marie; Hornslien, Karina Stensland; Krabberød, Anders Kristian; Bramsiepe, Jonathan; Brysting, Anne Krag & Grini, Paul Eivind (2018). The Genetic Basis of Post-Zygotic Hybridization Barriers Between Arabidopsis lyrata and A. arenosa. Fulltekst i vitenarkiv
• Johannessen, Ida Marie; Lafon-Placette, Clément; Hornslien, Karina Stensland; Bramsiepe, Jonathan; Bjerkan, Katrine & Brysting, Anne Krag [Vis alle 8 forfattere av denne artikkelen] (2017). The effect of gene and genome dosage on hybridization barriers in Arabidopsis lyrata and Arabidospsis arenosa. Fulltekst i vitenarkiv
• Johannessen, Ida Marie; Hornslien, Karina Stensland; Krabberød, Anders Kristian; Bramsiepe, Jonathan; Brysting, Anne Krag & Grini, Paul Eivind (2017). The genetic basis of post-zygotic hybridization barriers between Arabidopsis lyrata and A. arenosa. Fulltekst i vitenarkiv

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