The Role of Epigenetic Transcriptional Regulation in Brassica Vegetables: A Potential Resource for Epigenetic Breeding

Abstract

AbstractThe Brassica genus includes many economically important vegetables such as Chinese cabbage, cabbage, broccoli, cauliflower, pak choi, turnip, etc. The environment has a great impact on growth and development of Brassica vegetables. Epigenetic regulators are involved in various biological processes to regulate the transcription of genes related to agronomic traits in Brassica vegetables and are associated with their adaptation to the changing environments and stresses. Epigenetics refers to the modifications of chromatin states including DNA methylation and histone modification. Any of these modifications in chromatin states can epigenetically control transcriptional outputs, and the epigenetic regulators are involved in activation or silencing of many genes. In vernalization, accumulation of the repressive histone mark histone H3 lysine 27 tri-methylation by prolonged cold treatment causes the epigenetic silencing of a floral repressor, FLOWERING LOCUS C, to accelerate the flowering in Brassica vegetables. A contribution of epigenetic regulation in agronomically important traits such as hybrid vigor/heterosis or biotic and abiotic stress resistance is discussed. The dominance relationship between heterozygous alleles of pollen determinants of self-incompatibility is controlled by transcriptional silencing by the de novo DNA methylation in the recessive allele. Transposition or transcription of transposable elements (TEs) is regulated by DNA methylation, and sometimes TEs in the adjacent genic region affect gene expression through DNA methylation or histone modifications. As heritable epigenetic mutations may contribute to generation of a new phenotype, this chapter discusses epigenetic breeding in Brassica vegetables.KeywordsBrassicaEpigeneticsDNA methylationHistone modificationHeterosisStress responseSelf-incompatibilityVernalization