Structural variants (SVs) are abundant in plant genomes and influence agronomic traits, yet their regulatory interpretation remains challenging. Here, we combine pangenome-wide profiling of DNA methylation and chromatin accessibility across 20 barley genotypes, complemented by histone modification and chromatin interaction data in a subset of 10 genotypes. Comparative analysis of genotype-specific epigenomes reveals a globally conserved DNA methylation landscape across the barley pangenome alongside extensive regulatory variability at orthologous genes. We show that SVs do not broadly remodel global chromatin landscapes but instead act through context-dependent rewiring of local regulatory interactions. Despite this epigenomic stability, SVs may contribute to gene expression changes via chromatin contacts. Tissue-specific chromatin accessibility demonstrates that SV effects depend on developmental context. Integrating chromatin state variation with SVs at key vernalization genes explains epigenetic contributions to growth habit diversity. Together, these results provide a framework for interpreting the regulatory consequences of structural variation in crop genomes.
Zihao Zhu, Erwang Chen, Pavla Navrátilová et al.· bioRxiv· 0 citations
ABSTRACT Advancements in plant genome sequencing and assembly have enabled the production of increasingly accurate and contiguous genome sequences. Here, we present the chromosome‐level assembly of the durum wheat ( Triticum turgidum L. ssp. durum, cv. Svevo) reference genome produced using accurate long‐reads, optical mapping and Hi‐C. The new assembly (Svevo Rel.2.0) comprises 263 hybrid scaffolds with an N50 value of 112.3 Mb, arranged into 14 contiguous pseudomolecules spanning 10.4 Gb. The Svevo Rel.2.0 genome assembly was annotated using extensive short‐ and long‐read RNA sequencing data obtained from 60 tissue/treatment combinations. The resulting annotation comprises 68 154 high‐confidence protein‐coding genes, which have been integrated into a comprehensive transcriptome atlas accessible through an eFP browser. Annotation was manually curated for storage protein gene families and for Leucine‐Rich Repeat‐Containing Receptor genes yielding 3763 LRR‐CR loci. The genome assembly's accuracy and completeness were demonstrated by the correct reconstruction of the physical map of Tg1‐B (Tenacious glumes 1), a locus controlling the free threshing trait located on chromosome 2B that was not assembled in the previous genome release (Svevo Rel.1.0). A wealth of 6621 QTLs/MTAs from the literature were mapped onto Svevo Rel.2.0 to identify QTL hotspots and trait‐specific candidate genes. The ancestry of the durum genome to representative wild emmer populations from North‐Eastern and Southern‐Levant Fertile Crescent assessed by tracing haplotype transmission patterns revealed a clear mosaic pattern. This new durum reference genome, enhanced with advanced annotation and an expression atlas linked to QTLome data, is the most comprehensive tool available for durum wheat genomics.
E. Mazzucotelli, C. Forestan, Gina Zastrow-Hayes et al.· Plant Biotechnology Journal· 0 citations
