Development And Identification Of Three Special Hybrid Offsprings Between Wheat And Octoploid Agroticum

Thinopyrum intermedium(Host) B.D(2n=6x=42,E₁E₁E₂E₂StSt) is an allohexploid species and an important source carrying fruitfully valuable genes for improving the common wheat.In order to transfer these genes,a Th.intermedium was used to cross and backcrossed with recurrent common wheat Chuanmai107 several times and then the hybrid was selfed.Of these progenies,three new wheat lines AF1,AF2 and AF3 were developed in BC₂F₉ generation.The three lines were identified by morphology,cytology,genome in situ hybridization(GISH), SDS-PAGE,and SSR.The main results are as follows:1 Analysis of resistance genesChuanmai107 exhibited high susceptible to powdery milldew and stripe rust.AF1 and AF2 were immune to powdery mildew.AF2 was also immune to stripe rust.It is known that there were a number of powdery mildew and stripe rust resistance genes in Th.intermedium,however, none of them have been formally named.Genetic analysis showed that the powdery mildew resistance gene(s) of AF1 might be new gene(s) from the Th.intermedium and the stripe rust resistance gene(s) of AF2 might be different from any known genes.2 Cytological analysesChromosomal number of AF1,AF2 and AF3 counted at mitosis in root tip meristems were 42,44 and 44,respectively.The examination of pollen mother cells showed a mean of 21 bivalents with AF1,22 bivalents with AF2 and 22 bivalents with AF3.No univalent and other configuration have been found.There were one univalent in AF2×Chuanmai107 and AF3×Chuanmai 107 at MI of PMCs cells,respectively.The results suggested that the three lines might be cytologically stable.3 GISHGISH was carried out using the genomic DNA of Psudoergronia.strigosa as the probe and the genomic DNA of Triticum aestivum vat.'Chinese Spring' as the blocking.AF1(2n=42) was a small fragment translocation line.AF2(2n=44) was an alien disomic addition line with a pair of Thinopyrum E chromosomes in wheat background.AF3(2n=44) show added a pair of Thinopyrum St chromosomes in wheat background.4 SDS-PAGEHigh molecular weight glutenin subunit composition of AF1 was analyzed by sodium dodecy I sulphate polyacrylanide gel electrophoresis(SDS-PAGE).Chinese Spring(subunits: null,7+8 and 2+12),'Mianyangll'(subunits:1,7+8 and 5+12),Chuanmai107 and Th. intermedium were used as contrasts.AF 1 contained a subunit that came from Th.intermedium.In addition,there was a new subunit in AFlwhich was not existed in any parents.These results demonstrated that HWM subunit of Th.intermedium has been transferred into wheat and a new glutenin subunit was also created.5 Single seuquenee repeat(SSR) analysesThe analyses of SSR from 7 homoeologous groups of common wheat were carried out on the genomic DNAs of AF2,Chuanmai107 and Th.intermedium.Among 144 SSR primer pairs, xgwm382 could only amplified a band(about 90bp) in Agropyrum intermedium and AF2 and not in Chuanmai 107.Xgwm382 has been located on chromosome 2D,suggesting that it might be as the marker of the addition chromosome identificated and the addition chromosome in AF2 might be 2E of Th.intermedium.6 Agronomy analysesAF2 has some the morphological traits of Th.intermedium,i.e.tough glumes,waxy and slender stem.AF3 was different from parents and very dwarf(48cm).AF1 was resistance to powdery mildew and was a small fragment translocation and has the similar traits to parent chuanmai107,all these materials were very valuable for wheat genetics and breeding researches. As conclusion,AF1 was a small fragment translocation line between wheat and Th. intermedium.Powdery mildew resistance and SDS-PAGE analyses suggested that the translation fragment was most probably from the first homeologous groups of Th.intermedium.AF2 was an alien disomic addition line,which carried a new resistance gene to stripe rust from the 2E chromosomes of Th.intermedium.AF3 was added a pair of St chromosomes and possessed the dwarf character.In the study,the chromosomes and many alien valuable genes from Th. intermedium have been successfully transferred into common wheat.It was of importance in genetic study and breeding programs.