2012-09-05
The genes that make us robust
Scientists at SLU, Uppsala University and Dalarna University have screened the genome of the plant Arabidopsis thaliana for genes controlling trait robustness. Such genes were found to be common and to have large impact on the phenotypic variability for many traits. By experimentally showing that much of the phenotypic variability that was earlier thought to be stochastic noise is actually under genetic control, they open a new way to understand the contribution of genes to disease, evolution and selection response in plants and animals. The results were published in PLoS Genetics on August 2.
Most genetic studies explore primarily how genetic variability shift the mean level of a trait. The aim is then to find genetic variants that e.g. increase the susceptibility of disease or allow species to evolve new properties. An alternative, and still rather unexplored, potential level of genetic control is that of the variability. Here, the interest is to find genes that, once the population on average has a desirable property, decrease the variability of the trait to make a higher proportion of the population have a phenotype close to the optimum. For example, increase the proportion plants in a population that flowers at the optimal day or the number of animals that reach the desirable slaughter-weight at a defined day. In this study, the scientists reanalyzed a publicly available Arabidopsis thaliana dataset containing genotypes and phenotypes of plants sampled from around the world to explore the extent to which genes control the robustness the measured traits rather than their magnitude.
“Geneticists have for many years thought about how genes could regulate phenotypic robustness” says Örjan Carlborg, Professor at the Department of Clinical Sciences at SLU, who co-ordinated the study, “but this study gives a novel insight to how common it is on a genome-wide scale”.
By developing new theory for estimating how these variance-controlling genes contribute to quantitative genetic variation, the researchers showed that genetic variance control often contributes as much to the phenotypic variability as the genes controlling the trait mean. One such example is the genetic control of the level of Molybdenium in the plant, where the molybdenium transporter gene (MOT1) was shown to have a very large effect on the variability rather than the mean.
“Many molecules, such as trace elements, have to be maintained at certain levels in order to ensure a normal function of a biological system. We believe that this is an example where a mutation in such a gene disrupts its function, hence leading to large variation of the trait’’, said Xia Shen, who did this work as a PhD student at Uppsala University, but now works as a post-doctoral researcher at SLU.
The new theory and empirical findings reported in this study shows that we now have the necessary tools available to explore the impact of genetic robustness controlling genes in future studies of economically important traits in agriculture and disease.
Further reading
Read the article in PLoS Genetics
Contact information
Professor Örjan Carlborg, ph. +46-(0)76 210 91 14, email: orjan.carlborg@slu.se
Written by:
Mikael Jansson