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New Phytol. 2017 Oct;216(2):373-387. doi: 10.1111/nph.14510. Epub 2017 Mar 13.

Both maternally and paternally imprinted genes regulate seed development in rice.

Author information

1
State Key Laboratory of Crop Genetics and Germplasm Enhancement, Nanjing Agricultural University, 1 Weigang Road, Nanjing, 210095, China.
2
Department of Molecular Biosciences, Institute for Cellular and Molecular Biology and Center for Computational Biology and Bioinformatics, The University of Texas at Austin, Austin, TX, 78712, USA.
3
Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, 1 West Beichen Road, Beijing, 100101, China.

Abstract

Genetic imprinting refers to the unequal expression of paternal and maternal alleles of a gene in sexually reproducing organisms, including mammals and flowering plants. Although many imprinted genes have been identified in plants, the functions of these imprinted genes have remained largely uninvestigated. We report genome-wide analysis of gene expression, DNA methylation and small RNAs in the rice endosperm and functional tests of five imprinted genes during seed development using Clustered Regularly Interspaced Short Palindromic Repeats/CRISPR-associated gene9 (CRISPR/Cas9) gene editing technology. In the rice endosperm, we identified 162 maternally expressed genes (MEGs) and 95 paternally expressed genes (PEGs), which were associated with miniature inverted-repeat transposable elements, imprinted differentially methylated loci and some 21-22 small interfering RNAs (siRNAs) and long noncoding RNAs (lncRNAs). Remarkably, one-third of MEGs and nearly one-half of PEGs were associated with grain yield quantitative trait loci. Most MEGs and some PEGs were expressed specifically in the endosperm. Disruption of two MEGs increased the amount of small starch granules and reduced grain and embryo size, whereas mutation of three PEGs reduced starch content and seed fertility. Our data indicate that both MEGs and PEGs in rice regulate nutrient metabolism and endosperm development, which optimize seed development and offspring fitness to facilitate parental-offspring coadaptation. These imprinted genes and mechanisms could be used to improve the grain yield of rice and other cereal crops.

KEYWORDS:

DNA methylation; epigenetics; miniature inverted-repeat transposable element (MITE); noncoding RNA; rice; seed development

PMID:
28295376
DOI:
10.1111/nph.14510
[Indexed for MEDLINE]
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