Plant Breeding and Biotechnology

Indexed in /covered by CAS, KoreaScience & DOI/Crossref:eISSN 2287-9366   pISSN 2287-9358

Fig. 1.

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Fig. 1.

Mechanisms of epimutation induced by genetic variation.

(A) Insertion of the hAT transposon upstream of the CmWIP1 gene led to DNA hypermethylation and silencing of CmWIP1 gene, resulting in inhibition of male sexual organs development in melon. Reversion by loss of DNA methylation restores bi-sexual flower development.

(B) In wild-type Arabidopsis, SINE elements near FWA promoter are methylated and FWA is silenced, resulting in early flowering. In the fwa epiallele, SINE elements are hypomethylated and FWA is de-repressed, resulting in late flowering.

(C) In wild-type Arabidopsis, LINE elements next to BONSAI (BSN) gene are methylated. In ddm1 mutants, LINE DNA methylation spreads toward BSN coding sequences, causing DNA hypermethylation and silencing of BSN.

(D) The paramutagenic B′ allele contains seven methylated MITE repeats in an enhancer region 100-kb upstream of the booster1 (b1) gene whereas in the paramutable B-I allele, the MITE repeats are hypomethylated. When both B′ and B-I are present, the active B-I allele is converted to the inactive B′ state in a stable and heritable fashion.

(E) The Arabidopsis Col-0 ecotype has 3 unlinked, active PAI1, PAI2, PAI3 genes. In WS ecotype, an extra copy, PAI4, is present in a tail-to-tail orientation with PAI1. This PAI1-PAI4 inverted repeat induces heavy DNA methylation in all four WS PAI genes.

(F) In Sha accession, FOLT2 is a complex duplicated locus with multiple truncated copies that produces siRNAs and silence FOLT1 by RdDM. By contrast, Col-0 only has an active FOLT1 copy and lacks FOLT2. This copy number induced epigenetic variation was not revealed until close examination of sterile RIL progenies that inherited only the silenced FOLT1 from Sha, and chromosome segments from Col-0 that lacks FOLT2.

Plant Breeding and Biotechnology 2013;1:307-19
© 2013 Plant Breeding and Biotechnology