Genetic bottlenecks in cultivated populations occur when only a subset of wild individuals are brought under cultivation -- over time, the genetic base narrows as superior individuals are selectively propagated, resulting in elite cultivars that can be genetically depauperate. However, the authors found that many domesticated tree crops are derived from multiple areas, where seeds and cuttings were removed from geographically distinct wild populations. Moreover, many perennial species are highly heterozygous and clonal propagation maintains this heterozygosity at the individual level. Thus, perennial tree crops tend to have a much broader genetic bottleneck than annuals.
In light of the growing concern over monocultures and the loss of genetic diversity in our domesticated crops, Miller and Gross' review of perennial long-lived crops highlights the importance of maintaining long-lived perennials which may have lower environmental impacts as well as higher genetic variability within their populations.
"Understanding how basic evolutionary processes associated with agriculture (e.g., domestication bottlenecks, selective cultivation) impact plant species is critical for crop breeding and for the conservation of crop genetic resources," concludes Miller.
Scientists are also interested in how climate change might impact agriculture. In this framework, Miller is interested in exploring how perennial crops withstand heterogeneous climates over multiple years. "Little is known about the genomic basis of adaptation to climate in perennial plants, or how gene expression patterns may vary from year to year based on climatic conditions in a given location," she notes.
|Contact: Richard Hund|
American Journal of Botany