Cytological And Molecular Marker Identification Of Two Wheat-leymus Mollis Substitution Lines

Leymus mollis(Trin.)Pilger(NsNsXmXm,2n = 28),a wild relative of Triticum aestivum,possesses plenty of favorable traits that could be transferred to common wheat,such as large spikes,multiple spikelets,strong stems,tolerance of drought,cold,salts and barren soils,and resistance to multiple fungal and bacterial diseases.L.mollis is an allotetraploid species with an Ns genome originated from Psathyrostachys Keng,while an Xm genome of unknown origin.In order to further exploit and utilize the excellent germplasm resource of L.mollis,the cross between octoploid Tritileymus M842-16(AABBDDNsNs,2n = 56)and Triticum durum cv.D4286(AABB,2n = 28)was made,and two progenies are selected and identified by in situ hybridization,DNA molecular markers and morphological evaluation.The main results ar as followed:(1)DM2411 presented desirable agronomic traits and its average plant height was 43.33 cm,which was significantly lower than its parent Triticum aestivum 7182.Cytological observation showed 42 chromosomes in most root tip cells of DM2411 with 21 bivalents in 86% pollen mother cells at M I.A pair of Ns chromosomes and a bivalent with yellowish-green fluorescence signals were observed in root tip cells and pollen mother cells,respectively,via genomic in situ hybridization(GISH)analysis by using whole genomic DNA of P.huashanica as a probe.Three pairs of SSR markers which belong to the 2D genome of wheat cannot amplified expected bands in DM2411,which indicated the missing of the 2D chromosomes;three pairs of EST-STS markers assigned to the 2th wheat homocelogous group,generated specific bands for L.Mollis,P.Huashanica and DM2411,which proved that it should contain the 2Ns chromosomes from L.mollis.Consequentially,with its low height and long spike,DM2411 is a dwarf material with two 2Ns chromosome from L.Mollis.(2)Cytological observation showed 42 chromosomes in DM96 and 4 yellowish-green fluorescence signals via in situ hybridization(GISH)analysis by using whole genomic DNA of P.huashanica as a probe;21 bivalents in 84% pollen mother cells during M I and two bivalents with yellowish-green fluorescence signals.Three pairs of SSR markers which belong to the 2D and 3D genome of wheat respectively,cannot amplify expected bands in DM96,which indicated the missing of the 2D and 3D chromosomes;four pairs of EST-STS markers assigned to the 2th and 3th wheat homoeologous group,respectively,generated specific bands for L.Mollis,P.Huashanica and DM96,which proved that it should contain the 2Ns and 3Ns chromosomes from L.Mollis.Thus,DM96 is a genetically stable diploid substitution line with two 2 Ns ang two 3Ns chromosomes from L.Mollis,and exhibited excellent agronomic traits with significantly enhanced spike length,kernel length and fruiting rate.