Construction Of Standard Karyotype System For Avena Species And Chromosome Structural Variation

The genus Avena L.belong to the tribe Aveneae,subfamily Pooideae,Poaceae,consists of approximately 30 species.The genus Avena comprise of four genomes: A,B,C and D.The species is composed of six genomes with three ploidys of diploid,tetraploid and hexaploid.Due to the lack of oat reference genome and the close homology of some genomes for a long time,there is no probe marker that can accurately distinguish and identify oat chromosomes,therefore,there is no unified naming system among diploid,tetraploid and hexaploid chromosomes.Based on this,this study further optimizes repetitive sequence probes that can distinguish chromosomes of oat species based on the high-quality reference genome of oats,and develops seven homologous group probe librarys that can accurately identify homologous groups of oats.By combining repetitive sequence probes,a standard karyotype system that can accurately identify chromosomes of oat species is established.By establishing a standard karyotype system for oat species,the interspecific relationships and evolutionary relationships of oat species are revealed.Additionally,we discussed the application value of chromosome painting in identifying chromosomal structural variations in oat,providing cytological tools for the study of the origin and evolution of hexaploid cultivated oats and chromosome structural variations during oat polyploidization.1.Using a homologous group probe library and repetitive sequence probes,combined with chromosome karyotypes,a standard karyotype system for oat species based on repetitive sequence probes oligo-356,oligo-6C343,and p Am1 was successfully constructed.The use of repeated sequence probes oligo-356 in diploid A genome,a combination of repeated sequence probes oligo-356+oligo-6C343 in diploid C genome,a combination of probes oligo-356+oligo-6C343+p Am1 in tetraploid CD genome and hexaploid ACD genome have achieved accurate and effective identification of the chromosomes of oat species.A unified standard karyotype system has been established for chromosomes of diploid,tetraploid,and hexaploid species in the Avena.2.Exploring the phylogenetic relationships among Avena species based on the unified standard karyotype system for diploid,tetraploid,and hexaploid species.In the A genome diploid Avena,the four subtypes have their own unique cytological maps.There are certain differences in signal labeling between A.atlantica and A.lusitanica compared to other species.The signal pattern of A.atlantica is still more similar to the As genome subtype,but A.lusitanica may be more similar to the Ad genome species;The signal patterns of C genome diploid Avena are not significantly different,revealing that the internal differences within C genome diploid Avena are relatively small and the relationships are relatively close.There are varying degrees of differences in signal patterns among some chromosomes of the three species with CD genome tetraploidy;The signal differences between different species of ACD genome hexaploid are relatively small,and the main signal patterns tend to be consistent,indicating that the phylogenetic relationships between hexaploid species are relatively close.3.Exploring the origin and evolution of the A,C,and D genomes in oat polyploids based on the unified standard karyotype system for diploid,tetraploid,and hexaploid species.The signal pattern of the A subgenome in oat hexaploid is more similar to that of the As genome diploid,suggesting that the As genome diploid may participate in the evolutionary process as a donor of the A subgenome in hexaploid;The signal patterns of the C and D subgenomes in the hexaploid genome and the C and D subgenomes in the CD genome tetraploid A insularis are highly similar,suggesting that A.insularis is the closest existing species to the hexaploid species,but no diploid species with high homology to the C subgenome in the polyploid genome have been found;Comparing the signal of the D subgenome in polyploids with the existing A and C genome diploids,the Ac genome diploid A.canariensis may be the closest ancestor of the D genome in the existing oat diploid species.Therefore,this study supports that hexaploid oat is formed by hybridization and doubling of diploid A genome and tetraploid CD genome.4.Chromosome painting has application potential in identifying oat chromosome structural variations,and promoted the cytological identification of oat chromosomes: a large segment inversion from the CD genome tetraploid A.insularis to the ACD genome hexaploid A.sativa on chromosome 3C was validated;In A.insularis of the CD genome,the deletion fragment at the end of the short arm of chromosome 3C was detected at the end of chromosome 5D;three homologous translocations were identified in the C genome diploid,including 2C-1C\7C,3C-7C,and 5C-2C\4C;5 homologous group probe signal distribution to 4A chromosome in the As genome diploid.