Creation of novel wheat-rye 1BS/1RS translocation lines and their characterization by molecular cytogenetics

Chinese. 利用普通小麦（Tritlcum aestivum L．）品种小偃6号与黑麦（Secale cereale L．）品种德国白粒杂交，选育出一批带有黑麦抗病性状的小偃6号类型种质材料。应用连续C-分带-基因组原位杂交（sequent C―banding―G1SH）技术对上述材料进行染色体组成分析，筛选出2个小麦-黑麦1RS／1BL纯合易位系BC152-1-1和BC01―89-1。其中，BCl52-1-1（2n=42）除含有1对1RS／1BL易位染色体外，未见其他染色体变异；BC01―89―1（2n=43）除含有1对1RS／1BL纯合易位染色体外，还附加1条两端缺失的3R染色体。高分子量麦谷蛋白亚基（HMW―GS）组成分析和品质分析结果表明，BC152-1-1和BC01―89―1不仅含有来自小偃6号的14＋15优质亚基，而且其蛋白质含量、湿面筋含量和SDS沉降值等品质性状都得到显著改良。

English. The wheat-rye 1RS/1BL translocation has made a great contribution to the wheat production in the world since the Green Revolution. The 1RS/1BL translocations, for the existence of the short arm of rye（ Secale cereale L.） chromosome 1 R, often have many good traits such as high yield potential, muhi-resistance to diseases and good adaptation to acid soil. Many studies also illustrated that 1RS carries a lot of rust resistance genes （ Sr31, Lr26, Yr9 ） and powdery mildew resistance gene （ Pm8）. As a result, the short arm of 1R is frequently used as alien chromatin in wheat （Triticum aestivum L. ） improvement. But one major concern about this translocation recently is its single origin, with the consequence being loss of resistances to new races of stripe rust and powdery mildew. The other concern is that most of wheat cultivars carrying this chromosome arm were shown a defective grain quality, in particular, sticky dough and a reduction in dough strength. The reduction in dough strength was thought to be due to the presence of monomeric secalins from rye （Sec-1） and the substitution of glutenins and gliadins （ Glu-3 and Gli-1 ）. In order to develop new potentially usable disease resistant alien germplasm and improve the quality of 1RS/1BL translocations, cross was carried out between the Triticum aestivum L. cv. ＂Xiaoyan 6＂ and Secale cereale L. cv. ＂German White＂. ＂German White＂ is a winter rye cuhivar which is immune from stripe rust and powdery mildew. ＂Xiaoyan 6＂ is an elite winter wheat cuhivar derived from the cross of common wheat × Thinopyrum ponticum （2n = 70）. It possesses the characteristics of good processing quality, high yield potential, earliness, good stress tolerance and wide adaptation. Wheat-rye hybrids between ＂Xiaoyan 6＂ and ＂German White＂ were obtained in 1994. The F~ were treated with colchicines. The F2 and the subsequent generations were self-crossed and planted in the field. Each individual plant was selected with the qualities of seed set, wheat-like plant type and good resistance to rust and powdery mildew. A set of wheat-rye germplasm with resistances to rust and powdery mildew were bred. In order to identify genetic basis of these resistant lines, sequential C-banding-GISH （genomic in situ hybridization） was employed to analyze the chromosome compositions in somatic cells. As a result, two IRS/I BL homozygous translocation lines BC152-1-1 and BC01-89-1 were selected. One of them, BC152-1-1 had a chromosome number of 2n = 42 in somatic cell and its chromosome composition were 40 normal wheat chromosomes and one pair of IRS/IBL Robertsonian translocation chromosomes （Plate Ⅰ- A, B）. The other one, BC01-89-1 （2 n = 43） was a 1RS/1BL Robertsonian translocation line added one 3R chromosome with both terminal deletions （Plate Ⅰ- C, D）. In addition, the high-molecular-weight glutenin subunits （HMW-GS） in endosperm and major quality characteristics of ＂Xiaoyan 6＂, BC152-1-1 and BC01-89-1 were analyzed. The results showed that BC152-1-1 and BC01-89-1 carried HMW-GS 14 ＋ 15 derived from ＂Xiaoyan 6＂ （Fig. 1）, and their grain protein content, wet gluten content and SDS sedimentation value were greatly improved.