| Popis: |
The rates and patterns of somatic mutations in wild plants, as well as how they relate to longevity, are largely unknown1–3. Here, we examined the somatic mutation landscapes of slow- and fast-growing tropical species in central Borneo, Indonesia. Using newly-constructed genomes, we identified an average of 480 mutations in the slow-growing species (265-year-old, 44.1 m in height), which was five times greater than that observed in the fast-growing species (66-year-old, 43.9 m). The number of somatic mutations increased linearly with branch length. The somatic mutation rate per meter was higher in the slow-growing species, yet the rate per year remained constant across both species. The mutational spectra exhibited a dominance of spontaneous mutations, specifically cytosine-to-thymine substitutions at CpG sites. An analysis of nucleotide substitutions at both the intra- and inter-individual level revealed that somatic mutations are neutral within an individual, but those mutations transmitted to the next generation are subject to purifying selection. We developed a model to evaluate the relative contribution of cell division on mutational processes, and postulate that cell-division independent mutagenesis predominates. These findings deepen our understanding of mutational processes underlying the generation of genetic diversity in a tropical ecosystem. |
