Cytosine hypomethylation at CHG and CHH sites in the pleiotropic mutants of Mendelian inheritance in Catharanthus roseus

Journal of genetics

Vinay Sharma²  Vishakha Sharma¹  Renu Kumari¹  Gitanjali Yadav¹  Sushil Kumar1 3¹ 

[1] Genetical Genomics Laboratory, National Institute of Plant Genome Research (NIPGR), Aruna Asaf Ali Marg, New Delhi 110 067, India$$;Banasthali University, P.O. Banasthali Vidhyapeeth, Banasthali 304 022, India$$

关键词: bisulphite sequencing;    CMT3;    DNA demethylases;    DNA methyl transferases;    demethylation;    excision repair;    mutagenic hot spots;    phylogenetic relationships;    5S rDNA;    18S rDNA;    RdDM;    spontaneous mutagenesis.;   

DOI  :  

学科分类：生物科学（综合）

来源: Indian Academy of Sciences

【 摘 要 】

The 5S and 18S rDNA sequences of Catharanthus roseus cv ‘Nirmal’ (wild type) and its leafless inflorescence (lli), evergreen dwarf (egd) and irregular leaf lamina (ill) single mutants and lli egd, lli ill and egd ill double mutants were characterized. The lli, egd and ill mutants of Mendelian inheritance bore the names after their most conspicuous morphological feature(s). They had been chemically induced and isolated for their salt tolerance. The double mutants were isolated as morphological segregants from crosses between single mutants. The morphological features of the two parents accompanied salt tolerance in the double mutants. All the six mutants were hypomethylated at repeat sequences, upregulated and downregulated for many genes and carried pleiotropic alterations for several traits. Here the 5S and 18S rDNAs of C. roseus were found to be relatively low in cytosine content. Cytosines were preponderantly in CG context (53%) and almost all of them were methylated (97%). The cytosines in CHH and CHG (where H = A, T or C) contexts were largely demethylated (92%) in mutants. The demethylation was attributable to reduced expression of RDR2 and DRM2 led RNA dependant DNA methylation and CMT3 led maintenance methylation pathways. Mutants had gained some cytosines by substitution of C at T sites. These perhaps arose on account of errors in DNA replication, mediated by widespread cytosine demethylation at CHG and CHH sites. It was concluded that the regulation of cytosine methylation mechanisms was disturbed in the mutants. ILL, EGD and LLI genes were identified as the positive regulators of other genes mediating the RdDM and CMT3 pathways, for establishment and maintenance of cytosine methylation in C. roseus.

【 授权许可】

Unknown