Shirong Zhou;Mei‐Qing Xing;Zhihui Zhao;Yincong Gu;Yunping Xiao;Qiaoquan Liu;Xue Ho

Co-Innovation Center for Modern Production Technology of Grain Crops of Jiangsu Province, Key Laboratory of Plant Functional Genomics of the Ministry of Education, Yangzhou University, Yangzhou 225009, Jiangsu, China;State Key Laboratory of Crop Genetics and Germplasm Enhancement, Jiangsu Plant Gene Engineering Research Center, Nanjing Agricultural University, Nanjing 210095, Jiangsu, China; National Key Laboratory of Plant Molecular Genetics, CAS Center for Excellence in Molecular Plant Sciences, Chinese Academy of Sciences, Shanghai 200032, Chin;National Key Laboratory of Plant Molecular Genetics, CAS Center for Excellence in Molecular Plant Sciences, Chinese Academy of Sciences, Shanghai 200032, China;Shanghai OEbiotech, Shanghai 201210, China;Joint Center for Single Cell Biology, School of Agriculture and Biology, Shanghai Jiao Tong University, Shanghai 200240, China; National Key Laboratory of Plant Molecular Genetics, CAS Center for Excellence in Molecular Plant Sciences, Chinese Academy of Sciences, Shanghai 200032, China

DNA methylome;Heterosis;Rice;Reciprocally hybrid seeds;Embryo;Endosperm;ALTERED CIRCADIAN-RHYTHMS;YIELD;GENOME;GENE;DEMETHYLATION;TRANSCRIPTOME;EXPRESSION;REVEALS;VIGO

Heterosis is an important biological phenomenon and widely applied in agriculture. Although many studies have been performed by using vegetative organs of F-1 hybrid plants, how heterosis (or hybrid vigor) is initiated and formed, particularly the underlying molecular mechanism, remain elusive. Hybrid contemporary seeds of rice indica varieties 9311 and PA64 were innovatively used and analysis of DNA methylome of embryo and endosperm at early developing stages revealed the globally decreased DNA methylation. Genes, especially those relate to hormones function and transcriptional regulation present non-additive methylation. Previously identified heterosis-related superior genes are non-additively methylated in early developing hybrid contemporary seeds, suggesting that key genes/loci responsible for heterosis are epigenetically modified even in early developing hybrid seeds and hypomethylation of hybrid seeds after cross-pollination finally result in the long-term transcriptional change of F-1 hybrid vegetative tissues after germination, demonstrating that altered DNA methylation in hybrid seeds is essential for initiation regulation and maintenance of heterosis exhibiting in F-1 hybrid plants. Notably, a large number of genes show non-additive methylation in the endosperm of reciprocal hybrids, suggesting that endosperm might also contribute to heterosis. (C) 2021 Crop Science Society of China and Institute of Crop Science, CAAS. Production and hosting by Elsevier B.V. on behalf of KeAi Communications Co., Ltd.