Crop domestication processes

In crop domestication two processes can occur: convergent phenotype evolution that represents the appearance of the same traits in independent organisms, for example different cereal crops and seed dormancy (sometimes not involving the same loci) (Gross and Olsen, 2010); and parallel phenotype evolution, that, like the convergent type there is an appearance of the same trait but in related lineages (Gross and Olsen, 2010). Both processes result either from an unconscious selection, that may be the initial and main source of domestication syndrome, a natural selection resulted from human cultivation; or as opposed, a conscious selection by cultivation and propagation of plants with favored phenotypes (Meyer and Purugganan, 2013; Ross-Ibarra et al., 2007).

Another process involved in crop domestication could be polyploidy (genome duplication). Many species known as diploid are paleopolyploids, a study made by Van der Hoeven et al. (2002) indicates this event for several crops, among them maize which is genetically a diploid but through mapping data analysis is shown to have ancestral tetraploidy. The opposite may also occur, as it’s the case of the strawberry (Fragaria) where polyploidy occurred along evolution (Rousseau-Gueutin et al., 2008) and it’s species vary between diploids (2n = 2x = 14) to decaploids (2n = 10x = 70) (Rousseau-Gueutin et al., 2009). An example of this is Fragaria × ananassa (Duch.) an allo-octoploid (2n = 8x = 56) species formed from F. chiloensis (Mill.) and F. virginiana (Mill.) by chance hybridization in a botanical garden in Europe in the XVII century (Hummer et al., 2011).

Made by : Celso Santos and Patrícia Cruz

Bibliography

Gross, B. and Olsen, K. (2010). Genetic perspectives on crop domestication. Trends in Plant Science, 15(9), pp.529-537.

Hummer, K., Bassil, N. and Njuguna, W. (2010). Fragaria. Wild Crop Relatives: Genomic and Breeding Resources, pp.17-44.

Meyer, R. and Purugganan, M. (2013). Evolution of crop species: genetics of domestication and diversification. Nature Reviews Genetics, 14(12), pp.840-852.

Ross-Ibarra, J., Morrell, P. and Gaut, B. (2007). Plant domestication, a unique opportunity to identify the genetic basis of adaptation. Proceedings of the National Academy of Sciences, 104(Supplement 1), pp.8641-8648.

Rousseau-Gueutin, M., Gaston, A., Aïnouche, A., Aïnouche, M., Olbricht, K., Staudt, G., Richard, L. and Denoyes-Rothan, B. (2009). Tracking the evolutionary history of polyploidy in Fragaria L. (strawberry): New insights from phylogenetic analyses of low-copy nuclear genes. Molecular Phylogenetics and Evolution, 51(3), pp.515-530.

Van der Hoeven, R. (2002). Deductions about the Number, Organization, and Evolution of Genes in the Tomato Genome Based on Analysis of a Large Expressed Sequence Tag Collection and Selective Genomic Sequencing. THE PLANT CELL ONLINE, 14(7), pp.1441-1456.