Polyploidy—having multiple sets of chromosomes—is a common phenomenon in plants and has long intrigued evolutionary biologists. Polyploids often demonstrate greater adaptability to extreme environments than their diploid relatives, but the underlying genomic mechanisms remain poorly understood, particularly in wild species.
Strawberries (Fragaria spp.) represent a promising model for studying polyploid evolution, with a wide range of species exhibiting diverse ploidy levels. While the ancestry of cultivated octoploid strawberries has been intensively investigated, their tetraploid wild relatives remain relatively unexplored. In particular, the evolutionary origins and environmental adaptations of Chinese endemic tetraploids such as F. corymbosaand F. moupinensis are still unresolved. Due to these gaps, a deeper investigation into their genomic history is needed.
Researchers from Taizhou University and international collaborators published a study in Horticulture Research, 2024, which sheds light on the genomic evolution of two wild tetraploid strawberries. By sequencing and comparing the genomes of F. corymbosa, F. moupinensis, and three diploid species, the team clarified ancestral relationships and identified key gene families involved in adaptation to high-altitude environments. Their findings reveal that the tetraploids are not hybrids but rather autotetraploids, and they possess genetic traits likely selected for life in mountainous regions.
The researchers produced high-quality genome assemblies for the tetraploid species and their diploid relatives. Phylogenomic trees and sequence-based mapping confirmed that F. chinensis is the closest diploid ancestor to F. corymbosa and possibly to F. moupinensis as well. Both tetraploids showed no evidence of subgenome structure, supporting their classification as autotetraploids.
The study found significant expansion in gene families linked to UV-B response and DNA repair in both tetraploids. In contrast, gene families associated with pathogen response—such as those responding to wounding, fungi, and bacteria—were contracted. Transcriptome data revealed that genes involved in cell division and telomere maintenance were upregulated, including those for meiotic cell cycle, DNA-templated DNA replication, and meristem maintenance. Meanwhile, defense-related genes were downregulated, consistent with a shift in resource allocation to abiotic stress adaptation.
These findings reflect adaptations to high-altitude habitats—regions with intense UV radiation and low pathogen pressure. The results link genomic evolution directly to ecological traits, offering a model for how wild polyploids evolve through both structural and regulatory genomic changes.
“This research highlights how genome duplication can empower plants to adapt to challenging environments like high-altitude regions,” said Dr. Junmin Li, co-corresponding author of the study. “By combining genome sequencing, evolutionary analysis, and gene expression profiling, we were able to trace ancestry and link genomic changes to ecological adaptations. Our findings open up new possibilities for exploring how plants evolve under environmental stress.”
This research provides a genomic framework for understanding how wild polyploid plants adapt to extreme habitats. The confirmed ancestor-descendant relationship between F. chinensis and the tetraploids opens new avenues for studying adaptation mechanisms across altitudinal gradients. The gene families involved in UV resistance and reduced biotic stress response may serve as genetic targets for breeding more resilient strawberry varieties.
Moreover, the findings underscore the value of conserving wild Fragaria species as reservoirs of adaptive traits. Future studies using genome-wide association studies (GWAS) or quantitative trait loci (QTL) mapping could pinpoint specific adaptation-related genes, enhancing crop improvement and ecological restoration strategies.