title: Marker-Based Estimates Reveal Significant Nonadditive Effects in Clonally Propagated Cassava (Manihot esculenta): Implications for the Prediction of Total Genetic Value and the Selection of Varieties.
abstract: In clonally propagated crops, nonadditive genetic effects can be effectively exploited by the identification of superior genetic individuals as varieties. Cassava (Manihot esculentaCrantz) is a clonally propagated staple food crop that feeds hundreds of millions. We quantified the amount and nature of nonadditive genetic variation for three key traits in a breeding population of cassava from sub-Saharan Africa using additive and nonadditive genome-wide marker-based relationship matrices. We then assessed the accuracy of genomic prediction for total (additive plus nonadditive) genetic value. We confirmed previous findings based on diallel crosses that nonadditive genetic variation is significant for key cassava traits. Specifically, we found that dominance is particularly important for root yield and epistasis contributes strongly to variation in cassava mosaic disease (CMD) resistance. Further, we showed that total genetic value predicted observed phenotypes more accurately than additive only models for root yield but not for dry matter content, which is mostly additive or for CMD resistance, which has high narrow-sense heritability. We address the implication of these results for cassava breeding and put our work in the context of previous results in cassava, and other plant and animal species.
authors: Department of Plant Breeding and Genetics, Cornell University, Ithaca, New York 14853 wolfemd@gmail.com.
authors: Marnin D
authors: http://orcid.org/0000-0002-5929-5785
authors: MD
authors: Wolfe
authors: International Institute of Tropical Agriculture (IITA), Ibadan, Oyo, Nigeria.
authors: Peter
authors: http://orcid.org/0000-0002-7574-2645
authors: P
authors: Kulakow
authors: International Institute of Tropical Agriculture (IITA), Ibadan, Oyo, Nigeria.
authors: Ismail Y
authors: http://orcid.org/0000-0001-9966-2941
authors: IY
authors: Rabbi
authors: Department of Plant Breeding and Genetics, Cornell University, Ithaca, New York 14853.|United States Department of Agriculture - Agricultural Research Service (USDA-ARS), R.W. Holley Center for Agriculture and Health, Ithaca, New York 14853.
authors: Jean-Luc
authors: http://orcid.org/0000-0003-4849-628X
authors: JL
authors: Jannink
keywords: Cassava; GenPred; Genomic selection; Nonadditive effects; Shared Data Resources