Molecular Cytological Identification Of Multi-resistant Wheat-thinopyrum Intermedium Progenies

Wheat(Triticum aestivum L.AABBDD,2n=6x=42)is a widely cultivated gramineae plant in the world and one of the most important crops in China.Due to the long-term hybridization and artificial directional selection in the breeding process,the genetic background of wheat get gradually narrowed,the genetic variation is smaller and smallerand the improvement of yield,quality and resistance of disease and stress are limited.The relatives of wheat,Thinopyrum intermedium(2n=6x=42)contains a lot of excellent genes such as good quality,cold resistance,drought resistance,and disease resistance and it is an important tertiary gene source for improvement of wheat varieties.The excellent genes of Thinopyrum intermedium were introduced into wheat genome by distant hybridization and chromosome engineering technology and that created a lot of germplasm resources that can improve wheat quality,disease resistance and stress resistance,which will play a positive role in promoting improvement of wheat quality,high yield,disease resistance,stress resistance and the breeding of new varieties.In this study,wheat Jintai 170,part of double diploid TAI7047,and Thinopyrum intermedium and 82 wheat-Thinopyrum intermedium progenies were identified by artificial inoculation.Molecular cytology was using in wheat-Thinopyrum intermedium progenies which resistant to both powdery mildew and stripe rust.The number of mitotic metaphase chromosomes of root tip cells was observed,the fluorescence in situ hybridization(mc FISH)of oligo-psc119.2-1 and oligo-pta535-1.Meanwhile,based on the Contig sequencethe of Thinopyrum intermedium,identification of 160 specific STS markers from the sixth homologous group were carried out.The results are as follows:(1)The resistance to stripe rust,powdery mildew was identified in82 wheat-Thinopyrum intermedium progeny materials,18 materials which resistant to powdery mildew,27 materials which resistant to striperust and 10 materials which resistant to powdery mildew and stripe rust were obtained.The wild parents of double diploid TAI7047 and Thinopyrum intermedium were immune to powdery mildew and stripe rust while Jintai 170 was susceptible to two diseases and it is inferred that the resistance of these new Trititrigia lines to stripe rust races CYR32,CYR33,CYR34 and powdery mildew E09 strains was derived from octoploid Trititrigia TAI7047.(2)The chromosome numbers of 10 wheat-Thinopyrum intermedium progeny materials which were resistant to stripe rust and powdery mildew were observed and the statistical results showed that 8 of the 10 materials had 42 metaphase chromosomes,1 had 41 chromosomes and 1 had 44 chromosomes.CH357 which had excellent agronomic characters was selected from 8 wheat-Thinopyrum intermedium progeny materials with42 chromosomes.(3)CH357,a new Triticum line with resistance to stripe rust and powdery mildew,contains 42 chromosomes.ND-FISH(non denatured FISH)was used with oligonucleotide sequence probes oligo-psc119.2 and oligo-pta535.1 and results showed that only 40 chromosomes of CH357 were identical with its parent,Jintai 170.Compared with the FISH of Chineses spring,CH357 lost a pair of 6B chromosomes which was indicated that was a pair of homologous chromosomes because its shape and size were unanimous with the band type.Compared with the FISH karyotypes of TAI7047 and Thinopyrum intermedium,it was found that one pair of non wheat chromosomes in CH357 might be 6Js from Thinopyrum intermedium.(4)The PCR amplification of Thinopyrum intermedium,TAI7047,CH357,Jintai 170 and Chinese spring was carried out with 160 STS markers of the sixth homologous group in Thinopyrum intermedium.The results showed that the numbers of specific bands of Thinopyrum intermedium which be amplified in CH357 were 10,8 were located on Group6-Chro.1 and 2 were located on Group6-Chro.2.Combined withthe results of CH357 Mc-FISH,Group6-Chro.1 is the 6Js chromosome of Thinopyrum intermedium.To sum up,CH357 which is resistant to wheat stripe rust and powdery mildew is a wheat-Thinopyrum intermedium 6Js/6B substitution line and Its resistance may come from the 6Js chromosome of Thinopyrum intermedium.CH357 can be used as a new resource for genetic improvement in research of wheat stripe rust and powdery mildew resistance.The 8 STS markers which were selected from the 6Js chromosome of Thinopyrum intermedium provide more economical and convenient method for the detection of 6J chromosome or fragment of Thinopyrum intermedium.