The Distribution Of CR Element In Triticeae And ChIP-seq Analysis Of Roegneria Komarovi(Nevski) Nevski

Centromere is a special structure on the chromosome of eukaryotes,its function is conservative in different eukaryotes,but the structure is very different.The centromere remained condensed throughout the cell cycle,making the recombination exchange rate in this region lower than other chromosome regions,and the DNA sequence was relatively intact in evolution.Centromere is one of the important regions for the unification and coordination of different genomes in the evolution of polyploids.The study of centromeres is not only conducive to a further understanding of the formation and evolution of polyploids,but also to a deeper understanding the formation mechanism of new germplasm in the process of distant hybridization.Roegneria genus have achieved great results in distant cross breeding.Among them,Roegneria komarovi(Nevski)Nevski has been identified to be immune to stripe rust and may be used for wheat genetic improvement,studying its composition of centromere and the relationship with common wheat can provide theoretical basis for the utilization of wheat genetic species in wheat genetic improvement.In our previous study,we found that the retrotransposon Fatima element and Wegl element exist in wheat centromere or near centromere,and there are differences in the evolution of wheat ABD genome.In this study,we studied the distribution rules of the two elelemts in the Roegneria komarovi(Nevski)Nevski and other wheat species,as well as the affinity relationship between the St and Y genomes of Roegneria komarovi(Nevski)Nevski and the A,B and D genomes of wheat.At the same time,ChIP-seq analysis was carried out to find out the the centromere functional sequence of Roegneria komarovi(Nevski)Nevski,so as to provid a basis for the study of polyploid formation and evolution.Through experimental exploration,the following results are obtained:1.The Fatima elements were homologous cloned from Roegneria komarovi(Nevski)Nevski,and the sequence comparion between them and the Fatima elements in wheat showed that the sequence similarity of the two was about 80%.FISH analysis results showed that Fatima elements were diffused on the centromeres and chromosome arms of wheat A and B genomes,and the content of B genome was higer than of A genome.In Roegneria komarovi(Nevski)Nevski,Fatima elements were distributed in both Y genome and St genome centromeres and chromosome arms,and the abundance of elements in Y genome was richer than in St genome.In addition,the element existed in T.orientale,T.monococcum,Dasypyrum villosum and T.urartu of Poaceae.We speculate that Fatima is an ancient CR element in Poaceae,and abundance variation occurs in different genomes during evolution.2.The Wegl element cloned from Roegneria komarovi(Nevski)Nevski has very low similarity to common wheat.It is enriched in the centromere regions of Roegneria komarovi(Nevski)Nevski and other wheat species.In provious study,we find Wegl element may not participate in the formation of functional centromeres in hexaploid wheat.Next,we will verify whether it is a centromere functional element through ChIP.3.ChIP analysis of Roegneria komarovi(Nevski)Nevski showed that the wheat centromeres fuction sequence CRW still plays a role in the centromeres of Roegneria komarovi(Nevski)Nevski.4.Roegneria komarovi(Nevski)Nevski and wheat CENH3 have a good binding ability,which can create opportunities for recombination between the chromosome of Roegneria komarovi(Nevski)Nevski and wheat chroosomes.