| Common wheat(Triticum aestivum L.2n=6x=42)is currently the major food crop around the world,but the narrowing genetic base of wheat makes it difficult to increase wheat yield and quality.The related species of common wheat(Triticeae)is a great gene pool in which existed widely genetic diversities that wheat need in wheat improvement.In present,wide hybridization is one of main methods to be used to transfer the valuable genes of wheat wild relatives into the genetic background of wheat in order to reach the purpose of promoting wheat yield and quality.Thinopyrum intermedium is a wild relative of wheat that contains a variety of valuable genes that are good for wheat.By wide hybridization,valuable genes in Th.intermedium have been transferred into wheat and applied for wheat breeding and improvement.In present study,a stable hybridization progeny,line 12-1179,derived from the cross of common wheat and Th.intermedium,and another stable hybridization progeny,line 16-249,originated from the progenies of common wheat and partial amphiploid TAI7045(common wheat and Th.intermedium),were identified by molecular cytology technologies.Their resistances to powdery mildew and stripe rust in the two new materials were also tested in field.Chromosomal constitutions of line 12-1179 and 16-249 were characterized by genomic in situ hybridization(GISH)and fluorescence in situ hybridization(FISH).Resistances to powdery mildew and stripe rust in line 12-1179 and 16-249 was screened by field trial,as shown below.1.Line 12-1179 shows excellent resistance to strip rust and powdery mildew which are popular today.It can be used as a resource of resistance against two major wheat diseases in China.2.Cytogenetic investigation showed that the chromosome number of line 12-1179varied from 54 to 57,and most plants(78.57%)contained 56 chromosomes,suggesting line 12-1179 was a partial amphiploid.One to two additional telocentric chromosomes were found in some aneuploid plants of 2n=54 to 55.The chromosomes in 54.05%pollen mother cells(PMCs)of plants with 2n=56 formed 28 bivalents,averaging 27.26 bivalents and 1.33 univalents in 175 cells.Trivalents(0.01 per cell)and tetravalents(0.03 per cell)were occasionally detected at meiotic metaphase I in line 12-1179.3.GISH analysis using genomic DNA from Pseudoroegneria spicata as probe revealed that line 12-1179 only had 12 Th.intermedium chromosomes,including three pairs of St,and two pairs of J~s genomic chromosomes as well as one St-J~s translocated chromosome pair.Subsequently FISH using Oligo-pSc119.2-1 and Oligo-pTa535-1 as probes indicated that there were four 5D chromosomes in line 12-1179.All these results indicated line 12-1179 was a different partial amphiploid comparison with the reported partial amphiploid.All telocentric chromosomes observed in the aneuploid plants were5DL.4.Line 16-249 contained 42 chromosomes,in which one pair of wheat 4D chromosome is replaced by one pair of St genomic chromosomes by GISH and FISH analyses.The analysis of PLUG(PCR-based Landmark Unique Gene)revealed that the two St chromosomes in line 16-249 should belong to the fourth group chromosomes.Thus,line 16-249 is a 4St(4D)disomic substitution of wheat-Th.intermedium.Disease tests demonstrated that line 16-249 is highly susceptible to powdery mildew and stripe rust.However,heading date of line 16-249 was earlier at least one week than its common wheat parent,and line 16-249 might be a good material for wheat early maturation breeding.In conclusion,line 12-1179 and 16-249 can be used to transfer desirable genes into wheat and applied in wheat breeding program. |
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