Autopolyploidy Leads To Genomic Changes In Arabidopsis Thaliana

Polyploidization has made the outstanding contributions on plant genome reorganization and evolution.Polyploidy is a widespread feature of plant genomes,about 35% of the vascular plants,of which 15% flowering plants and 30% of fern borned with polyploidy,which suggests polyploidy has close link to the formation of new species.As a typical model of polyploidy,autopolyploid has been postulated evolutionary dead ends because a large number of repeat sequences result in the decrease of effective selection of gene,while other researchers believe that autopolyploidization will affect the normal meiosis period of homologous chromosomes pairing and separation,improves the genetic recombination frequency,promoted the genetic diversity.Compared with allopolyploid,autopolyploid has received little attention.For the limited data available so far,the evolutionary outcome of genome diversity in autopolyploids remains controversial in comparison with its ancestor diploids.In the present study,the effects of autopolyploidy on genome diversity were revealed at a genome-wide scale by comparative analyses of polymorphism between Arabidopsis autopolyploids(autotetraploids and autotriploids)and related diploids in three ecotype(Col?Ler?Ws)within the first 10 successive inbred generations using amplified fragment length polymorphism(AFLP).The polymorphic bands were sequenced and analyzed,and semi-quantitative PCR were used to analyzed the change of gene expression.Here are the results:1.We got hybrid triploid plants by using the Arabidopsis thaliana autotetraploid as female parent and diploid as male parent.2.The Arabidopsis thaliana autopolyploids(autotetraploids and autotriploids)and related diploids were analyzed by using AFLP technique,the results showed that autopolyploidization lead to genome structure variation compared autopolyploid with diploid,and the genome structure variation of autotriploid is greater than the autotetraploid.3.The Arabidopsis thaliana autotetraploid and their diploid in three ecotype(Col?Ler?Ws)were analyzed by using AFLP technique,the results indicated that autopolyploidization lead to genome structure variation by using different ecotypes,and the number of missing bands are more than new bands compared autopolyploid with diploid.4.The Arabidopsis thaliana autotetraploid and their diploid in different generations were analyzed by using AFLP technique,the results suggested that in contrast with diploids,the rapid genomic changes(including gain and loss of DNA sequences)in autopolyploids were definitely found within the first generations after autopolyploidization,but slow down and probably stabilized in the higher generations as a source of genetic diversity in the long term.5.The Arabidopsis thaliana WT and three mutants(Spoll-1?Dmc1?Prd1)in different ploidy were analyzed by using AFLP technique,the results indicated that difference in rate(polymorphic bands/total bands)of autotetroploid was higher than diploid,while the change is not significant or multiple,which suggested that the autopolyploid genome may soften the effect of the gene mutation.6.The sequencing of these DNA fragments indicated that these changes occurred both on genic and inter-genic(or intronic)regions.7.The semi-quantitative PCR showed that the expression of some corresponding genes in the genic regions was obviously affected(including upregulation,downregulation and silence)in autopolyploids.The experimental results showed that the homologous polyploidization caused the variation of genome structure and gene expression.This experiment provides a theoretical basis for further study of autopolyploid genome structure evolution.