A Variational Bayes Genomic-Enabled Prediction Model with Genotype x Environment Interaction

There are Bayesian and non-Bayesian genomic models that take into account GxE interactions. However, the computational cost of implementing Bayesian models is high, and becomes almost impossible when the number of genotypes, environments, and traits is very large, while, in non-Bayesian models, there are often important and unsolved convergence problems. The variational Bayes method is popular in machine learning, and, by approximating the probability distributions through optimization, it tends to be faster than Markov Chain Monte Carlo methods. For this reason, in this paper, we propose a new genomic variational Bayes version of the Bayesian genomic model with GxE using half-t priors on each standard deviation (SD) term to guarantee highly noninformative and posterior inferences that are not sensitive to the choice of hyper-parameters. We show the complete theoretical derivation of the full conditional and the variational posterior distributions, and their implementations. We used eight experimental genomic maize and wheat data sets to illustrate the new proposed variational Bayes approximation, and compared its predictions and implementation time with a standard Bayesian genomic model with GxE. Results indicated that prediction accuracies are slightly higher in the standard Bayesian model with GxE than in its variational counterpart, but, in terms of computation time, the variational Bayes genomic model with GxE is, in general, 10 times faster than the conventional Bayesian genomic model with GxE. For this reason, the proposed model may be a useful tool for researchers who need to predict and select genotypes in several environments.

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