Transcriptomic stress responses in Vaccinium spp. F1 hybrids: Implications for temperature-resilient cranberry breeding using a crop wild relative

Abstract

O_LICranberry (Vaccinium macrocarpon) is an important North American fruit crop with vulnerability to temperature extremes and a relatively recent domestication history. Hybridization with a cold-adapted crop wild relative (CWR), V. oxycoccos, offers a strategy for improving temperature stress tolerance. C_LIO_LIWe conducted RNA sequencing (RNA-seq) on V. macrocarpon and F1 hybrids between V. macrocarpon and V. oxycoccos subjected to acute heat and cold stress, capturing early transcriptional responses up to 30 minutes (heat) and 95 minutes (cold) after treatment onset. We then evaluated differences in responses across genotypes and stress conditions. C_LIO_LIDifferential expression analysis and functional profiling revealed cold-induced differences in pathways related to photosynthesis, ribosomes, defense, and hormone signaling. No subgenome-specific functional specialization was observed. Two F1 hybrids exhibited suggestive cold resilience, with expression changes elevated at 60 minutes but declining by 95 minutes. Hybrids also displayed substantial regulatory variation under stress and transgressive downregulation of photosynthesis genes under ambient conditions. C_LIO_LIThese findings suggest that V. oxycoccos introgression could be utilized in breeding cold-tolerant cranberry cultivars. Variation observed between F1 hybrids reflects the diversity introduced through CWR germplasm and provides opportunities for selection. Conservation of V. oxycoccos and other CWRs remains critical for future crop improvement. C_LI Plain Language SummaryCranberries face increasing threats from temperature extremes. We explored crossbreeding cultivated cranberry (Vaccinium macrocarpon) and a cold-adapted wild relative (V. oxycoccos) to improve resilience to temperature stress. Hybrids showed different gene expression patterns from their parents, especially under cold stress. Our findings support the value of wild relatives in crop improvement and emphasize the importance of protecting wild plant diversity.