| Non-denatured fluorescence in situ hybridization(ND-FISH)based on oligonucleotide probe has been widely used in the chromosome identification of wheat crops because of its advantages of accuracy,rapidity and economy.By comparison,oligonucleotide probes for the identification of maize chromosomes need to be further enriched.The design of appropriate oligonucleotide probes based on tandem repeats is the key to the success of NDFISH.So far,there are few known tandem repeats in the maize genome.Therefore,this study based on the theory that gramineous plants are evolutionarily related,developed oligonucleotide probe based on the tandem repeats sequence of wheat.Maize chromosome segmental specific oligonucleotide probes have been screened,as well as the barley chromosome and rye chromosome segmental specific oligonucleotide probes.The evolutionary mechanism of the corresponding sequence of oligonucleotide probes in wheat,barley,rye and maize genome has been preliminary analysised.The following is summary of the results:1.Six oligonucleotide probes were screened from 524 newly designed and reported wheat oligonucleotide,which produced hybridization signals in specific segements of chromosome 6 and chromosome 2 of maize,and show polymorphism among different maize materials.These oligonucleotide probes are: Oligo-440.2,Oligo-42,Oligo-3B10.2,Oligo-4A259,Oligo-7B6822.1 and Oligo-7DS.33.2.ND-FSIH analysis was conducted on six barley materials including More X,common wheat Chinese spring and rye Kustro using 6 screened probes.It was found that two oligonucleotide probes Oligo-440.2 and Oligo-42 produced signals on centromere of all 7 pairs of chromosomes of barely More X;while in maize probe Oligo-440.2 produced the signal on NOR of chromosome 6S,probe Oligo-440.2 produced the signal on NOR of chromosome 6S and chromosome 2L;in wheat,Oligo-42 produced signals on pericentromeric regions of chromosome 1AS,6BL and 7BL,centromeric region of chromosome 2B,intercalary regions of chromosome 3BS,6BS and 7BL,centromeric and pericentromeric regions of 5B,Oligo-42 produced signals on intercalary regions of chromosome 3BS and 5BS,pericentromeric region of chromosome 5BL,suggesting that these chromosomal segments are related.In addition,oligonucleotide probes Oligo-3B10.2,Oligo-4A259,Oligo-7DS.33 produced signals on NOR of chromosomes 5H and 6H in barely More X;while in maize the signal located on NOR of chromosome 6S;in rye,the probes Oligo-4A259 produced signals on the telomeric regions of chromosome 1RS,2RS,3R,4RS,5RS,6RS,one of the 3RL and both arms of 7R,Oligo-7DS.33 produced signals on the telomeric regions of chromosome 4RS,5RS,6RS and both arms of 7R,suggesting that these chromosomal segments are related.These results also showed the homologous relationship between the chromosome 6 of maize,chromosome 5B of wheat,chromosome3 R and 4R of rye and chromosome 5H and 6H of barley.3.The corresponding original sequence the 6 probes selected in this experiment were compared with the genome data of corn,barley and rye,and result only turned out that there are 95 sequences in rye scaffolds sequence which homologous to the original sequence >4A259 of Oligo-4A259.Combined with ND-fish analysis results,it was found that the current reference genomes of corn,barley and rye have missed a large number of tandem repeats,so there is still a lot of room for improvement in their quality,and ND-FISH technology can provide reference.This study developed chromosome segmental specific oligonucleotide probes,provideded a convenient way to identify the chromosome segment of maize,barely and rye.To some extent,it reflectes the evolutionarily relationships of these plants,provides theoretical guidance to evolutionary research of tandem repeat sequences and chromosomes. |
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