title: Epigenetic Changes in Hybrids.
abstract: Genome-wide approaches to the study of hybrid vigor have identified epigenetic changes in the hybrid nucleus in Arabidopsis (Arabidopsis thaliana), maize (Zea mays), and rice (Oryza sativa). DNA methylation associated with 24-nucleotide small interfering RNAs exhibits transallelic effects in hybrids of Arabidopsis and other species. Some of the transmethylation changes are inherited and some affect gene expression. Hybrids have larger leaves than those of the parents and have increases in cell size and number. The increased leaf size results in a greater photosynthetic capacity, which may support the increased vegetative and reproductive yields of the F1 hybrids. Genes and metabolic pathways that have altered expression relative to the parents include loci involved in responses to hormones and to biotic and abiotic stress. Whereas epigenetically induced changes in gene expression may contribute to hybrid vigor, the link between the transcriptional changes and the hybrid phenotype is not confirmed. Recurrent selection of high yielding F1 lines from the F2/F3 of a number of crops has fixed heterosis yields in pure breeding lines. These hybrid-like lines may have valuable applications in crop systems.
authors.affiliation: Commonwealth Scientific and Industrial Research Organization Agricultural Flagship, Canberra, Australian Capital Territory 2600, Australia (I.K.G., R.G.-B., L.W., A.Z., P.-C.L., W.J.P., E.S.D.);Division of Plant Sciences, Research School of Biology, Australian National University, Canberra, Australian Capital Territory 0200, Australia (M.G.); andUniversity of Technology, Sydney, New South Wales 2007, Australia (W.J.P., E.S.D.) ian.greaves@csiro.au.
authors.forename: Ian K
authors.initials: IK
authors.lastname: Greaves
authors.affiliation: Commonwealth Scientific and Industrial Research Organization Agricultural Flagship, Canberra, Australian Capital Territory 2600, Australia (I.K.G., R.G.-B., L.W., A.Z., P.-C.L., W.J.P., E.S.D.);Division of Plant Sciences, Research School of Biology, Australian National University, Canberra, Australian Capital Territory 0200, Australia (M.G.); andUniversity of Technology, Sydney, New South Wales 2007, Australia (W.J.P., E.S.D.).
authors.forename: Rebeca
authors.initials: R
authors.lastname: Gonzalez-Bayon
authors.affiliation: Commonwealth Scientific and Industrial Research Organization Agricultural Flagship, Canberra, Australian Capital Territory 2600, Australia (I.K.G., R.G.-B., L.W., A.Z., P.-C.L., W.J.P., E.S.D.);Division of Plant Sciences, Research School of Biology, Australian National University, Canberra, Australian Capital Territory 0200, Australia (M.G.); andUniversity of Technology, Sydney, New South Wales 2007, Australia (W.J.P., E.S.D.).
authors.forename: Li
authors.identifier: http://orcid.org/0000-0003-3661-7259
authors.initials: L
authors.lastname: Wang
authors.affiliation: Commonwealth Scientific and Industrial Research Organization Agricultural Flagship, Canberra, Australian Capital Territory 2600, Australia (I.K.G., R.G.-B., L.W., A.Z., P.-C.L., W.J.P., E.S.D.);Division of Plant Sciences, Research School of Biology, Australian National University, Canberra, Australian Capital Territory 0200, Australia (M.G.); andUniversity of Technology, Sydney, New South Wales 2007, Australia (W.J.P., E.S.D.).
authors.forename: Anyu
authors.initials: A
authors.lastname: Zhu
authors.affiliation: Commonwealth Scientific and Industrial Research Organization Agricultural Flagship, Canberra, Australian Capital Territory 2600, Australia (I.K.G., R.G.-B., L.W., A.Z., P.-C.L., W.J.P., E.S.D.);Division of Plant Sciences, Research School of Biology, Australian National University, Canberra, Australian Capital Territory 0200, Australia (M.G.); andUniversity of Technology, Sydney, New South Wales 2007, Australia (W.J.P., E.S.D.).
authors.forename: Pei-Chuan
authors.identifier: http://orcid.org/0000-0001-6619-4299
authors.initials: PC
authors.lastname: Liu
authors.affiliation: Commonwealth Scientific and Industrial Research Organization Agricultural Flagship, Canberra, Australian Capital Territory 2600, Australia (I.K.G., R.G.-B., L.W., A.Z., P.-C.L., W.J.P., E.S.D.);Division of Plant Sciences, Research School of Biology, Australian National University, Canberra, Australian Capital Territory 0200, Australia (M.G.); andUniversity of Technology, Sydney, New South Wales 2007, Australia (W.J.P., E.S.D.).
authors.forename: Michael
authors.initials: M
authors.lastname: Groszmann
authors.affiliation: Commonwealth Scientific and Industrial Research Organization Agricultural Flagship, Canberra, Australian Capital Territory 2600, Australia (I.K.G., R.G.-B., L.W., A.Z., P.-C.L., W.J.P., E.S.D.);Division of Plant Sciences, Research School of Biology, Australian National University, Canberra, Australian Capital Territory 0200, Australia (M.G.); andUniversity of Technology, Sydney, New South Wales 2007, Australia (W.J.P., E.S.D.).
authors.forename: W James
authors.identifier: http://orcid.org/0000-0001-7314-9074
authors.initials: WJ
authors.lastname: Peacock
authors.affiliation: Commonwealth Scientific and Industrial Research Organization Agricultural Flagship, Canberra, Australian Capital Territory 2600, Australia (I.K.G., R.G.-B., L.W., A.Z., P.-C.L., W.J.P., E.S.D.);Division of Plant Sciences, Research School of Biology, Australian National University, Canberra, Australian Capital Territory 0200, Australia (M.G.); andUniversity of Technology, Sydney, New South Wales 2007, Australia (W.J.P., E.S.D.).
authors.forename: Elizabeth S
authors.identifier: http://orcid.org/0000-0002-7850-591X
authors.initials: ES
authors.lastname: Dennis
mesh_terms: D017360:Arabidopsis / Q000235:genetics* / Q000502:physiology; D001947:Breeding; D002678:Chimera; D019175:DNA Methylation; D044127:Epigenesis, Genetic; D018506:Gene Expression Regulation, Plant; D006823:Hybrid Vigor / Q000235:genetics*; D012275:Oryza / Q000235:genetics* / Q000502:physiology; D010641:Phenotype; D010788:Photosynthesis; D018515:Plant Leaves / Q000235:genetics / Q000502:physiology; D003313:Zea mays / Q000235:genetics* / Q000502:physiology