Ing the manuscript and analysed the resulting data. VP conceived this study and drafted the manuscript. PubMed ID:https://www.ncbi.nlm.nih.gov/pubmed/28154141 All authors have approved the final manuscript.References 1. Birchler JA, Yao H, Chudalayandi S, Vaiman D, Veitia RA. Heterosis. Plant Cell. 2010;22(7):2105?2. doi:10.1105/tpc.110.076133. 2. Sreenivasulu N, Schnurbusch T. A genetic playground for enhancing grain number in cereals. Trends Plant Sci. 2011;17(2):91?01. doi:10.1016/j. tplants.2011.11.003. 3. Darwin C. The effects of cross and self fertilisation in the vegetable kingdom. 1878. 4. Duvick DN. Biotechnology in the 1930s: the development of hybrid maize. Nat Rev Genet. 2001;2(1):69?4. doi:10.1038/35047587. 5. G tner T, Steinfath M, Andorf S, Lisec J, Meyer RC, Altmann T, et al. Improved heterosis prediction by combining information on DNA- and metabolic markers. PLoS One. 2009;4(4):e5220. doi:10.1371/journal. pone.0005220. 6. Bell GDM, Kane NC, Rieseberg LH, Adams KL. RNA-Seq analysis of allele-specific expression, hybrid effects, and regulatory divergence in hybrids compared with their parents from natural populations. Genome Biol Evol. 2013;5(7):1309?3. doi :10.1093/gbe/evt072. 7. Guo B, Chen Y, Zhang G, Xing J, Hu Z, Feng W, et al. Comparative proteomic analysis of embryos between a maize hybrid and its parental lines during early stages of seed germination. PLoS One. 2013;8(6):e65867. doi:10.1371/journal.pone.0065867. 8. Flint-Garcia SA, Buckler ES, Tiffin P, Ersoz E, Springer NM. Heterosis is prevalent for multiple traits in diverse maize germplasm. PLoS One. 2009;4 (10):e7433. doi:10.1371/journal.pone.0007433. 9. Bruce AB. The mendelian theory of heredity and the augmentation of vigor. Science. 1910;32(827):627?. doi:10.1126/science.32.827.627-a. 10. Crow JF. Alternative hypotheses of hybrid vigor. Annu Rev Genet. 1948;33(5):477. 11. Jones DF. Dominance of linked factors as a means of accounting for heterosis. Annu Rev Genet. 1917;2(5):466. 12. Lamkey KR, Edwards J. Quantitative genetics of heterosis. In: Genetics and exploration of heterosis. 1999. 13. Powers L. An expansion of Jones’s theory for the explanation of heterosis. Am Nat. 1944;78(776):275?0. 14. Lippman ZB, Zamir D. Heterosis: revisiting the magic. Trends Genet. 2007;23 (2):60?. doi:10.1016/j.tig.2006.12.006. 15. Goff SA, Zhang Q. Heterosis in elite hybrid rice: speculation on the genetic and biochemical mechanisms. Curr Opin Plant Biol. 2013;16(2):221?. doi:10.1016/j.pbi.2013.03.009. 16. Lari e A, Mangin B, Jasson S, Combes V, Dumas F, Jamin P, et al. The genetic basis of heterosis: multiparental quantitative trait loci mapping reveals contrasted levels of apparent overdominance among traits of agronomical interest in maize (Zea mays L.). Annu Rev Genet. 2012;190 (2):795?11. doi:10.1534/genetics.111.133447. 17. Li Z, Luo L, Mei H, Wang D, Shu Q. Overdominant epistatic loci are the primary genetic basis of inbreeding depression and heterosis in rice. I. Biomass and grain yield. Annu Rev Genet. 2001;158:1737?3. 18. Reif J, Hallauer A, Melchinger AE. Heterosis and heterotic patterns in maize. Maydica. 2005;50:215?3. 19. Andorf S. A systems biological PD98059 structure approach towards the molecular basis of heterosis in Arabidopsis thaliana. 2011. OPUS-IDN/5117.Emmrich et al. BMC Evolutionary Biology (2015) 15:Page 15 of20. Andorf S, G tner T, Steinfath M, Witucka-Wall H, Altmann T, Repsilber D. Towards systems biology of heterosis: a hypothesis about molecular network structure applied for the Arabidopsis metabolome. EURASIP J.