| DNA methylation is one of important epigenetic modification, generally existing in all thegenomes of the plant and the animal. DNA methylation has a positive effect on plant，which playsan important role in genetic defense, regulating gene expression and controlling development andgrowth of plant.DNA methylation is involved with all functions of genome, includingtranscription, replication, DNA repairing，rearrangement，cell differentiation and so on.Hickory（Carya cathayensis Sarg.,Carya Nutt., Juglandaceae）is distributed in Tianmumountain area which is located between Zhejiang and An’hui Province of China. As an excellentspecies of economic trees, hickory is provided with nuts and wood. At present，seedlingcultivation and bud grafting are two conventional propagation techniques in hickory, but theseedlings can not keep the excellent properties of the mother tree while grafting is limited bymany facters. With the need of new varieties cultivation, the immature embryos are used asexplants to induce callus and somatic embryos to develop regenerated plants has been studied. Thelevel and change of DNA methylation at different developmental stages of hickory were analyzedby the methylation-sensitive amplified polymorphism (MSAP) method. The main results weresummarized as follows：（1） In this study, the analysis of DNA Methylation of eight developmental stages of immatureembryos after per-PCR and selective-PCR on the1%agarose gel. The bands of per-PCRare smear show their size were similar，and the bands of selective between100bp-750bp.The result showed there are differences among eight developmental stages clearly. And itcan prove the efficiency.（2） The level of methylation reach the highest percentage (32.48%) on12weeks after openpollination, while a minimum of percentage of26.34%on the9and10weeks. Thisshows a significant difference on different periods of DNA methylation and the change ofthe DNA methylation are certain regularity on hickory.（3） Result showed DNA methylation levels and types are same or not in differentdevelopmental stages. For example, the DNA methylation percentage were26.34%in9and10weeks after open pollination, but the type of DNA methylation are different. Thehalf methylation on9week is6.91%, and20.48%on10weeks, the total methylation on9 week is19.43%while15.86%on10weeks. The level of half methylation are decreasefrom10weeks to16weeks on immature embryos, while the total methylation showedincreasing. The pattern of change has certain regular change during the stages ofdevelopment.（4） The change of de-methylation always happened on all the development of hickory. On12weeks and13weeks, the de-methylation sites are most obvious change are22, the DNAmethylation and de-methylation exist on the stages of the development.（5） There is a close relationship between the embryogenic frequency and differentdevelopmental stages of genome methylation level and type. DNA methylation levels andtypes have the obvious changed from9to12weeks when the immature embryos are easyto dedifferentiation. However, DNA methylation levels and types are tended to be stable.Therefore, the gene expression in embryogenic cells was regulated by DNA methylationand demethylation.（6） The analysis of different bands on same methylation sites from different developmentalstages are100bp-300bp, the sequence alignment analysis has been NADP dehydrogenasesubunit analogs showed that DNA methylation plays an important role on development ofimmature embryo in the hickory. |
PDF Full Text Request