The Composition And Evolutionary Analysis Of The Functional Centromere Sequence Of Brachypodium Ergatum

The Brachypodium distachyon as the ideal model plant of Poaceae.The Brachypodium distachyon sequencing achieved and its cytogenetical results are promote the further research of cereal crops and energy plants.However,the sequence composition and evolutionary mechanism of B.distachyon centromeres are not in-depth analysis.We use the antibody of centromeric special histone CENH3 to identify centromeric region and use ChIP-seq to get centromeric DNA sequences for further analysis.The main results are showed that:(1)We use bioinformatics method based on sequence similarity to analyze the special repetitive centromeric sequences in B.distachyon.We get 5 repetitive sequences of B.distachyon Bd21 centromeres Then the repetitive sequence was examined by FISH.The result show that the special DNA sequences of B.distachyon centromeres are consisted of satellite repetitive(CentBd)and retrotransposons(CRBds).(2)We use fiber-FISH technology to analyze satellite repetitive sequences(CentBd)and retrotransposons(CRBds).The result show that the CentBd has the series distribution of centromeric region and its length of centromeric region is 27 to 144bk.However,CRBds have disperesd distribution of centromeric region.(3)Three Brachypodium distachyon inbred lines are hybridized with probs of CentBd and detected signal gray values.The result show that centromeric satellite copy numbers are different in different chromosome centromeres of B.distachyon.Even among closely related inbred lines,centromeric satellite copy numbers have undergone differing levels of deletion or amplification.(4)According to cytological analysis of centromeric retrotransposon(CRBds)in different species of Brachypodium.Indicating retrotransposon exist differentiation in different species.This result provides new evidence for the genetic relationship and classification of Brachypodium.(5)To analysis the expression of centromere genes,we use transcriptome data and RT-qPCR method.The result show that centromeric region also has active genes.The statistics and analysis of genetic density of centromeric region,we find the genetic density of centromeric region is low and lower than other parts of chromosomes.And most genes are exists in the H3 of centromeric region.The development of this subject provide a powerful data support to further analyze sequences of centromeres and its evolution mechanism.And it also provide basic knowledge for the research of gramineous crops.