title: Physical localization and DNA methylation of 45S rRNA gene loci in Jatropha curcas L.
abstract: In eukaryotes, 45S rRNA genes are arranged in tandem arrays of repeat units, and not all copies are transcribed during mitosis. DNA methylation is considered to be an epigenetic marker for rDNA activation. Here, we established a clear and accurate karyogram for Jatropha curcas L. The chromosomal formula was found to be 2n=2x=22=12m+10 sm. We found that the 45S rDNA loci were located at the termini of chromosomes 7 and 9 in J. curcas. The distribution of 45S rDNA has no significant difference in J. curcas from different sources. Based on the hybridization signal patterns, there were two forms of rDNA - dispersed and condensed. The dispersed type of signals appeared during interphase and prophase, while the condensed types appeared during different stages of mitosis. DNA methylation analysis showed that when 45S rDNA stronger signals were dispersed and connected to the nucleolus, DNA methylation levels were lower at interphase and prophase. However, when the 45S rDNA loci were condensed, especially during metaphase, they showed different forms of DNA methylation.
authors.affiliation: Key Laboratory of Crop Genetics and Physiology of Jiangsu Province/Key Laboratory of Plant Functional Genomics of Ministry of Education, College of Agriculture, Yangzhou University, Yangzhou, Jiangsu, China.
authors.forename: Zhiyun
authors.initials: Z
authors.lastname: Gong
authors.affiliation: Key Laboratory of Crop Genetics and Physiology of Jiangsu Province/Key Laboratory of Plant Functional Genomics of Ministry of Education, College of Agriculture, Yangzhou University, Yangzhou, Jiangsu, China.
authors.forename: Chao
authors.initials: C
authors.lastname: Xue
authors.affiliation: Key Laboratory of Crop Genetics and Physiology of Jiangsu Province/Key Laboratory of Plant Functional Genomics of Ministry of Education, College of Agriculture, Yangzhou University, Yangzhou, Jiangsu, China.
authors.forename: Mingliang
authors.initials: M
authors.lastname: Zhang
authors.affiliation: Key Laboratory of Crop Genetics and Physiology of Jiangsu Province/Key Laboratory of Plant Functional Genomics of Ministry of Education, College of Agriculture, Yangzhou University, Yangzhou, Jiangsu, China.
authors.forename: Rui
authors.initials: R
authors.lastname: Guo
authors.affiliation: Key Laboratory of Crop Genetics and Physiology of Jiangsu Province/Key Laboratory of Plant Functional Genomics of Ministry of Education, College of Agriculture, Yangzhou University, Yangzhou, Jiangsu, China.
authors.forename: Yong
authors.initials: Y
authors.lastname: Zhou
authors.affiliation: Key Laboratory of Crop Genetics and Physiology of Jiangsu Province/Key Laboratory of Plant Functional Genomics of Ministry of Education, College of Agriculture, Yangzhou University, Yangzhou, Jiangsu, China.
authors.forename: Guoxin
authors.initials: G
authors.lastname: Shi
mesh_terms: D019175:DNA Methylation; D056426:Genetic Loci / Q000235:genetics*; D031286:Jatropha / Q000166:cytology / Q000235:genetics*; D007621:Karyotyping; D008938:Mitosis / Q000235:genetics; D012335:RNA, Ribosomal / Q000235:genetics*
chemical_list: D012335:RNA, Ribosomal; C088179:RNA, ribosomal, 45S