Genome-wide characterization of extant clonal diversity in Chilean Carmenere

Abstract

Carmenere is a widely cultivated and internationally recognized grapevine cultivar in Chile, yet genetic variation among its clones remains poorly characterized. Early studies based on SSR and AFLP markers detected limited polymorphism, but these approaches interrogate only a small fraction of the genome, leaving the extent of clonal diversity unresolved. Here, we generated an improved chromosome-scale diploid genome assembly of Carmenere FPS clone 02 and characterized clonal genomic diversity by sequencing 36 biological replicates representing 12 clones maintained in Chile, including heritage selections rescued from old producer vineyards by Vina Santa Carolina as part of its Bloque Herencia conservation program, and commercial nursery-derived clones. Focusing on low-frequency variants and using replicate-aware consensus calling, we identified more than 9,000 private single nucleotide variants (SNVs) and small indels per clone, providing high-resolution markers for clonal identification. Although most variants were located in repetitive or intergenic regions, a subset affected coding sequences, with genes involved in plant-pathogen interactions, transport, and secondary metabolism most frequently impacted. While variant-affected genes associated with wine anthocyanin content, TA, pH, and alcohol percentage were identified, broader phenotypic characterization will be required to assess their biological significance. Overall, this study provides a genome-wide characterization of extant clonal diversity in Carmenere, with implications for clonal selection and genetic resource conservation.