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CG hypomethylation leads to complex changes in DNA methylation and transpositional burst of diverse transposable elements in callus cultures of rice
Author(s) -
Hu Lanjuan,
Li Ning,
Zhang Zhibin,
Meng Xinchao,
Dong Qianli,
Xu Chunming,
Gong Lei,
Liu Bao
Publication year - 2020
Publication title -
the plant journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.058
H-Index - 269
eISSN - 1365-313X
pISSN - 0960-7412
DOI - 10.1111/tpj.14531
Subject(s) - biology , transposable element , dna methylation , genome , mutant , genetics , methylation , callus , dna , gene , gene expression
Summary CG methylation ( m CG) is essential for preserving genome stability in mammals, but this link remains obscure in plants. OsMET1‐2, a major rice DNA methyltransferase, plays critical roles in maintaining m CG in rice. Null mutation of OsMET1‐2 causes massive CG hypomethylation, rendering the mutant suitable to address the role of m CG in maintaining genome integrity in plants. Here, we analyzed m CG dynamics and genome stability in tissue cultures of OsMET1‐2 homozygous (−/−) and heterozygous (+/−) mutants, and isogenic wild‐type (WT). We found m CG levels in cultures of −/− were substantially lower than in those of WT and +/−, as expected. Unexpectedly, m CG levels in 1‐ and 3‐year cultures of −/− were 77.6% and 48.7% higher, respectively, than in shoot, from which the cultures were initiated, suggesting substantial regain of m CG in −/− cultures, which contrasts to the general trend of m CG loss in all WT plant tissue cultures hitherto studied. Transpositional burst of diverse transposable elements (TEs) occurred only in −/− cultures, although no elevation of genome‐wide mutation rate in the form of single nucleotide polymorphisms was detected. Altogether, our results establish an essential role of m CG in retaining TE immobility and hence genome stability in rice and likely in plants in general.