| Cytosine is usually widely methylated in the genomes of higher plant.The methylation patterns and levels are dynamic and variable throughout the plant development cycles.There are differences in DNA methylation between tissues and organs of different maturity and between tissues and organs of different parts of plants.Hypermethylation and hypomethylation occur frequently in the process of tissue culture.Therefore,this stable and reversible regulation of temporal and spatial gene expression regulates gene expression,thus affecting plant development.At present,the differences of DNA methylation in different tissues and organs of plants only focus on Arabidopsis thaliana,rice and other model plants,as well as cash crops such as soybean and cotton,while the differences of DNA methylation in different tissues and organs of millet and callus cultured at different time are seldom studied.In order to investigate the relationship between DNA methylation and morphogenesis and organ differentiation in different tissues and organs of millet,we used shoots,seedlings,mature leaves,young panicles and callus of Yugu 1 as experimental materials,and analyzed the differences of DNA methylation in these eight tissues and organs by MSAP technology.The results were as follows:1.In this study,2014 cytosine loci and 1886-1924 bands were detected in eight tissues and organs of millet.The methylation level of eight tissues and organs ranged from14.00% to 16.34%,the highest was 24-month callus,and the lowest was seedlings.With the increase of tissue and organ maturity and the time of callus culture,the methylation level increased as a whole.2.Compared with mature leaves,the differences of hypomethylation and hypermethylation in other 7 tissues and organs were 2.23%-4.57% and 2.38%-6.21%respectively.In the two variations,the callus was higher as a whole than the organs of different maturity,indicating that the occurrence of methylation events in the callus played an important role in the dedifferentiation process and the maintenance of dedifferentiation status.3.Among the tissues and organs with different maturity,the difference between seedlings and mature leaves is the greatest,which indicates that the changes ofmethylation was great during the development from seedlings to mature leaves,and the difference between young panicles and mature leaves is the smallest.4.We retrieved and sequenced the bands of different methylation.Through chromosome localization and functional alignment,we found that the mutation sequence was distributed on 1,2,3,4,5 and 9 chromosomes.Genes related to mitochondrial pyruvate vector 4 and protein ZINC-induced promoter 1 were homologous to the known functional genes in millet,suggesting that these functional genes may affect the growth and differentiation of different tissues and organs of millet through the changes of DNA methylation modification. |
