Selection And Identification Of Wheat-Thinopyrum Intermedium Substitution Line Conferring Resistance To Stripe Rust

Wheat stripe(yellow)rust,caused by Puccinia striiformis Westend.f.sp.Tritici,is an important disease for crops in China as the maximal prevalence area in the world.Use of the resistance of wheat differential host and resistant cultivar breeding can control the disease economically,safely and effectively.Thinopyrum intermedium,one of the relative species of common wheat,is a kind of dominant wheat germplasm resource for the resistance to stripe rust in wheat genetic improvement.With using Chinese spring phlb as recurrent parents and awnless Zhong 4(a partial chromosome of Thinopyrum intermedium)as donor parents,that is backcross selection,the offspring BC₂F_7～9were acquired.Cytology check and genome in situ hybridization(GISH), were used for the translocation lines and substitution lines detection.The results as follows:1.On the basis of previous study,the height of plant and the agronomic traits of the offspring(861ines)BC₂F₇ of wheat-Thinopyrum intermedium were investigated and evaluated.There are 20 lines(P13,P30,P38,P54,P55,P58,P59,P64,P65,P66,P67,P68,P69,P71,P78,P88,P89,P90,P91,P92),with strip rust resistant character for wheat and good performance for agronomy.2.Twenty lines with preferable traits were tested to identify the seedling resistance type to the prevalent virulence races of Puccinia striiformis f.sp.tritici.CY32 and Su-14 (Shuiyuan 11).To Su-14 and CY32,the Chinese spring phlb showed susceptible; Zhong 4 showed immunity;20 lines were classified 3 kinds as resistant,susceptible and segregation respectively.The chromosome(chromatin)of Zhong 4 with resistance to stripe rust have been transformed to some lines of BC₂F_7～9.3.By using the mitosis metaphase of the root and stalk tip of 20 lines,we screened a line P67 that was taken as investigation object.The results showed that there are 6 lines (2n=42),namelyP13,P30,P38,P58,P67 andP69,total 29 plant lines.We can deduce that the resistant lines maybe have chromosome or chromosome segment that come from Thinopyrum intermedium translocation line or substitution line. The plant lines(2n=42)of P67,P38 and P58 were detected by GISH(Genome in situ hybridization)with the probe of Thinopyrum intermedium genomic DNA using the digoxigenin-labeled and the blocker of Chinese Spring genomic DNA.The results showed that P67-1-12-2-2,P58-1-001 and P38-2-005 are a wheat-Thinopyrum intermedium alien disomic substitution line.4.AFLP was applied to study the P67-1-12-2-2,Zhong 4 and Chinese spring phlb One primer(P-ACA/M-CCA)revealed a specific Thinopyrum intermedium DNA band in P67-1-12-2-2.