The techniques for genetic improvement of crops during the green revolution contributed to an increase of agricultural production in developing countries. In 1970, the scientist Norman Borlaug, pioneer in producing semidwarf varieties and icon of the green revolution, received the Nobel Peace Prize for his efforts in order to strengthen worldwide agricultural production through biotechnology.
The new research published in PNAS affirms that European and Asian Arabidopsis thaliana populations -- a model organism in plant biology that is naturally distributed across the Northern Hemisphere -- have 1-5% semidwarf individuals.
"Geographical distribution does not response to population spreading, as semidwarf individuals present different mutations which prove an independent origin," explains Rubén Alcázar, Ramón y Cajal researcher at the Department of Natural Products, Plant Biology and Edaphology of the Faculty of Pharmacy. "This recurrent phenotype is interesting -- adds the expert -- as it indicates any kind of evolution advantage."
After the footprint of natural evolution
A reduction of gibberellins is translated into short-height in many rice and barley semidwarf varieties. Gibberellins are plant hormones involved in height growth. These varieties have a mutated gene that affects an enzyme involved in the final stage of gibberellins biosynthesis. However, the reduction does not affect any other plant developmental process in which the hormone is involved. That is due to the existence of other functional genes which replace gibberellins in other developmental processes. "It can be affirmed that this mutation mainly affects plant height," underline the authors of the paper.
The new research suggests that mutations which occur in semidwarf due to a reduction of gibberellin are favoured in some local populations. "In this case, a mutation selected by humans to increase crop yield is also selected by nature in response to an environmental factor which remains unknown," highlights Rubén Alcázar. "This proves that the study of the natural evolution of populations, even in model plants such as Arabidopsis, enables to foresee solutions to agriculture challenges," concludes Alcázar
- L. Barboza, S. Effgen, C. Alonso-Blanco, R. Kooke, J. J. B. Keurentjes, M. Koornneef, R. Alcazar. Arabidopsis semidwarfs evolved from independent mutations in GA20ox1, ortholog to green revolution dwarf alleles in rice and barley. Proceedings of the National Academy of Sciences, 2013; 110 (39): 15818 DOI: 10.1073/pnas.1314979110
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