| Wheat(Triticum aestivum L.,AABBDD,2n=42)is one of the three most important food crops in this world.It has been cultivated for more than 8,000 years and play an important role in the production and development for agriculture in the world.The relative species of wheat are containing many excellent genetic resources,which are suitable for the genetic improvement of wheat genome,among which the most successful one is 1RS.1BL translocation line that crossing between wheat and rye.However,the genetic basis of 1RS.1BL translocation line was too narrow in the long-term directional breeding process,and the resistance of most 1RS.1BL translocation lines gradually weakened or even lost due to the new pathogenic physiological subspecies produced since 1990 s,so this translocation line could not meet the needs of modern agriculture.Therefore,when the 1RS chromosome arms lost their resistance,it will soon be eliminated by the wheat breeding program.However,it is undeniable that the 1RS.1BL translocation line can increase the yield potential of wheat about 5%,which makes a great contribution for human.Introducing the diversity of rye into wheat to create the diversity of 1RS.1BL translocation lines,and then utilizing the diversity of 1RS.1BL translocation lines to solve the current difficulties in wheat genetic improvement is a feasible method to further use the 1RS chromosome arm,and the creation of new wheatrye translocation lines is also imminent.“Chuan-nong” series wheat cultivars are the most important in southwest of China since 2000 s,which have many excellent agronomic traits,such as great disease resistance,high tiller numbers,stay green,and so on.The analysis of their chromosomes structure can provide more information for the wheat breeding in southwest of China.In this study,non-denaturing fluorescence in situ hybridization(ND-FISH)combined with five oligonucleotide probes(oligo-pSc119.2-1,oligo-pTa535-1,oligo-Ku,oligopSc200 and oligo-pSc250)were used to analyze the chromosomal signal polymorphism and source of 21 “Chuan-nong” wheat cultivars.In addition,this study also screening the homozygous generation that crossing between the three “Chuan-nong” wheat cultivars(CN23,CN25 and CN27)which have good agricultural traits with different varieties of rye(Chile,Qinling,Weining and Jingzhou rye).Then some innovative results were obtained as follows:1.The standard karyotype of “Chuan-nong” wheat cultivars(lines)was established to provide assistance for wheat breeding in southwest China.2.The oligonucleotide probes Oligo-pSc119.2-1 and Oligo-pTa535-1 are highly polymorphic in wheat chromosomes.These most chromosomes of 21 “Chuan-nong” wheat cultivars showed same signals patterns as the standard signal pattern of MY11,but there were still several showed different among them.A total of 88 mutants of signal patterns were distributed on 79 chromosomes(17.9%,79/441).Among them,26 mutants are in A chromosome group(17.6%,26/147),and 40 are in B chromosome group(27.2%,40/147,do not including 1RS chromosome),and 13 are in D chromosome group(8.9%,13/147),respectively.For the mutant signal patterns,60(68.2%,60/88)were the mutants of OligopSc119.2-1,24(27.3%,24/88)were the mutants of Oligo-pTa535-1,and in 4(4.5%,4/88)mutants were these two probes signals replaced each other.There were more Oligo-pSc119.2 mutants on the 2A and 7B chromosomes and more Oligo-pTa535 mutants on the 5D chromosomes than on the other chromosomes.3.To reveal the sources of the signal pattern polymorphisms,two groups of “Chuannong” wheat cultivars were compared with their wheat parents,respectively.The results showed that most of the chromosomal signal mutants came from the parents,the source of polymorphism is an independent assortment during crossing,and the progeny selectively inherited the signal pattern of one of the parents.However,the 7BL chromosome arms of CN26 and CN27 showed a completely different signal pattern from their wheat parents and MY11.According the results,CN19 was shown to be a normal wheat cultivar without any rye chromatin,but R3301 was a 1RS.1BL translocation line.Therefore,the effects of monosomy could explain the mutations in CN26 and CN27.The other group is the 5D chromosome centromeric regional signal pattern of CN12 and CN17,which is different from their parents and MY11.Both their parents are 1RS.1BL translocation lines,without the formation of monomer addition,however,the progenies of this cross,CN12 and CN17,also showed different signal patterns,suggesting that a normal cross between wheat can also result in DNA mutations.4.The identification of progenies from the free combination crossing between three “Chuan-nong” wheat cultivars(CN23,CN25 and CN27)with different varieties of rye(Chile,Qinling,Weining,and Jingzhou rye),have been selected 1RS.1BL translocation lines that contain different 1RS chromosome arm from different rye and different wheat cultivars,new 3RS.6AL translocation lines and a small number of new translocation lines,such as 1RS.4AS,1RS.5BL and 3RL.2AS;2R disomic addition line,5R disomic addition line,1R(1A)disomic substitution line,and a homozygous double translocation line contain the 1RS.1BL and 3RS.6AL translocation chromosomes,3R(2A)disomic substitution line that containing a pair of 3RS.6AL translocation chromosomes;Among wheat,4B and 6B chromosomes reciprocal translocation line,5A and 3B chromosomes reciprocal translocation line,7B and 3D chromosomes reciprocal translocation line.A material about 5A and 3B,7B and 3D chromosomes double reciprocal translocation line that containing a pair of 3RS.6AL.The agronomic traits of these new materials need to be determined by further studies.The oligonucleotide probe used in this experiment can well replace the repeat sequence probe and be used for ND-FISH identification: the combination of oligonucleotide probe Oligo-pTa535-1 and Oligo-pSc119.2-1 can distinguish all 42 wheat chromosomes;another combination of oligonucleotide probes about Oligo-Ku,Oligo-pSc200 and Oligo-pSc250 can identify rye chromosomes in the wheat genetic background. |
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