Transgenerational epigenetic cold tolerance in rice

As rice has expanded northwards from its center of origin, it has been exposed to deeper and longer periods of cold. Male fertility is particularly sensitive to cold. Song et al. designed a clever strategy to study mechanisms of cold tolerance. They subjected meiotic-stage cold-sensitive rice varieties to cold and at each generation selected panicles with increased cold tolerance, determined by increased seed set. After three rounds of cold treatment, they carried reciprocal crosses with the same strain that had not been subjected to cold, and all the progeny showed cold tolerance, indicating that it behaved as a dominant trait. Furthermore, this adaptive trait was stable for five generations even in the absence of continued cold treatment. Genomic and epigenomic analysis led the authors to identify the gene responsible for the acquired, heritable cold tolerance, which they named ACT1 (AcquiredColdTolerance1, encoding an arabinogalactan protein). Interestingly, ACT1 contains no sequence variation between cold-tolerant and sensitive varieties, but instead contains a differentially-methylated region. The epiallele in the cold-tolerant varieties is hypomethylated in a promoter region that is bound by a cold-induced transcription factor, Dof1. Furthermore, they found the hypomethylated epiallele is more abundant in landraces from northerly regions. As the authors observe, this study provides a mechanistic explanation for the inheritance of acquired characteristics that was proposed by Lamarck more than 200 years ago. (Summary by Mary Williams @PlantTeaching.bsky.social) Cell 10.1016/j.cell.2025.04.036