Biology subjects

Rognli, O. A.

Publications and source records attributed to Rognli, O. A..

4 recordsLinked to original sources

bioRxiv2026

A constitutively active cortical nitrate-uptake cell state underlies nitrogen-use efficiency in perennial ryegrass

Perennial ryegrass (Lolium perenne) is the most widely sown forage grass of temperate agriculture and a major sink for fertiliser nitrogen, yet the cellular basis of its nitrogen-use efficiency (NUE) is unknown. We built a single-nucleus atlas of 76,684 root nuclei from a high- and a low-NUE genotype under matched nitrogen resupply. High-affinity nitrate uptake is concentrated in one cortical cell state that co-expresses nine NRT2 transporters and all three NAR2 partner proteins, a state that whole-root RNA-seq of the same tissue cannot resolve. Under reduced nitrogen the low-NUE genotype induces this state, whereas the high-NUE genotype does not; it expresses NRT2.3 at a higher baseline and uses different NRT2 paralogs, with one array member nearly silent. Across 44 annual and perennial Pooideae genomes, the same gene families show no life-history difference in copy number, evolutionary rate or selection intensity. Their regulation, however, varies in the same direction as between the two genotypes: the perennial Brachypodium sylvaticum expresses the NRT2.3 ortholog at the level that the annual B. distachyon reaches only under nitrogen deprivation, and an N-efficient barley genotype does not induce the transporters that an N-sensitive genotype induces. NUE differences are therefore associated with constitutive versus inducible deployment of a conserved toolkit, and the expression and presence/absence variants we identify are candidate breeding markers. The atlas, the first for a forage grass, is released as an open web resource.

plant biology↗

bioRxiv2025

Genomic prediction of agronomic traits in perennial ryegrass (Lolium perenne L.) and genotype x environment interactions at the limit of the species distribution

BackgroundIn breeding the aim is to identify and accumulate beneficial variants. However, detection of these variants may be challenging in the presence of extensive genotype x environment interactions (GxE), as variant effects will be conditional on environment. MethodsThe study assesses the performance of 264 diploid perennial ryegrass accessions in a multi-environment field trial. We investigate the extent of GxE, for yield (total dry matter) and persistence traits, i.e. winter kill and spring cover, under environmental conditions experienced in Nordic and Baltic regions at the limit of the species distribution. Two different approaches to modelling GxE were tested: reaction norm and envirotyping, and the models were validated under three different breeding scenarios. ResultsOur analysis documented the presence of significant GxE interaction for all traits investigated in the study. Validation showed improvements in prediction accuracy when accounting for GxE: up to 4% for yield when predicting in unobserved environments, and up to 22% and 9% for spring cover and winter kill, respectively when predicting unobserved germplasm. Genome-wide-association-studies (GWAS) were utilized to detect genetic variants with marginal effects (environment-independent effect) and conditional effects (environment-dependent effects). Results showed the presence of large-effect genetic variants with marginal effects, in addition to few QTL whose effects were adaptive under specific environmental conditions while neutral or deleterious under different environmental conditions. ConclusionThis study demonstrates the usefulness and limitations of genomic prediction models for predicting GxE in highly diverse samples, and describes the extent of GxE interactions at the limit of species distribution for perennial ryegrass. Finally, our study points toward adaptive variation, which may enhance persistence of perennial ryegrass populations in Nordic and Baltic growing conditions.

genetics↗

bioRxiv2024

Surviving under Ice: Insights into gene-expression changes during ice encasement in timothy (Phleum pratense L.)

The predicted increase in frequency and duration of winter warming episodes (WWEs) at the higher northern latitudes is expected to negatively impact the forage production in this region. The formation of non-permeable ice cover due to WWEs creates hypoxic or anoxic conditions for plants leading to severe winter damages. Knowledge about molecular mechanisms underlying various winter stresses is crucial to develop cultivars with better winter survival under changing climatic conditions. In the current study, we aimed at identifying genes involved in ice encasement stress responses by RNAseq in the perennial forage grass timothy (Phleum pratense L.) and study gene expression differentiation due to field survival using cultivars with diverse genetic backgrounds. The LD50 estimates varied across cultivars and material. The expression of ethylene-responsive transcription factors, alcohol dehydrogenase, pyruvate decarboxylase, sucrose synthase, dehydrins, and heat shock proteins were highly upregulated under ice encasement conditions. Functional analysis of differentially expressed genes revealed that the upregulated genes were involved in glycolysis, pyruvate metabolism, carbon metabolism, and biosynthesis of amino acids while genes involved in photosynthesis, phenylpropanoid biosynthesis and flavonoid biosynthesis pathways were downregulated. The results from the current study indicate a substantial overlap of ice encasement stress responses with those of hypoxia and freezing stresses. In addition, the potential strategies leading to higher ice encasement tolerance of timothy are outlined. Furthermore, differences in gene expression between field survivors and the original plant material, and differences between ice encasement responses of northern-adapted and southern-adapted cultivars are briefly discussed.

plant biology↗

bioRxiv2019

ForageGrassBase: Molecular resource for the forage grass Festuca pratensis Huds.

BackgroundMeadow fescue (Festuca pratensis Huds.) is one of the most important forage grasses in temperate regions. F. pratensis is a diploid (2n =14) outbreeding species that belongs to the genus Festuca. Together with Lolium, they are the most important genera of forage grasses in temperate regions. F. pratensis has good winter survival, with high quality dry matter yields and persistency, and is suitable both for frequent-cutting conservation regimes and for grazing. It is a significant component of species-rich permanent pastures in the temperate regions, ensuring high forage yield under harsh climatic conditions where other productive forage grass species are unable to grow. However, genomic resources for F. Pratensis is not available so far.\n\nResultsThe draft genome sequences of two F. pratensis genotypes \"HF7/2\" and \"B14/16\" are reported in this study. Here, using the draft genome, functional annotation datasets of two F. pratensis cultivars, we have constructed the F. pratensis genome database http://foragegrass.org/, the first open-access platform to provide comprehensive genomic resources related to this forage grass species. The current version of this database provides the most up-to-date draft genome sequence along with structural and functional annotations for genes using Genome Browser (GBrowse). In addition, we have integrated comparative genomic tracks for F. pratensis genomes by mapping F.pratensis genome to the barley, rice, Brachypodium and maize genomes. We have integrated homologus search tool BLAST also for the users to analyze their data. Combined, GBrowse, BLAST and downloadble data gives an user friendly access to F. pratensis genomic resouces. All data in the database were manually curated.\n\nConclusionTo our knowledge, ForageGrassBase is the first genome database dedicated to forage grasses. It provides valuable resources for a range of research fields related to F. pratensis and other forage crop species, as well as for plant research communities in general. The genome database can be accessed at http://foragegrass.org. In the near future, we will expand the ForageGrassBase by adding genomic tools for other forage grass species, as soon as their genomes become available.

plant biology↗