Creation Of The Wheat-Rye Small Segment Translocation Carrying Stripe Rust-resistant And Sec-1 Genes And Identification By Molecular Cytogenetics

Stripe rust caused by Puccinia striiformis f.sp. tritici West, is the most importantfungal disease that causes great yield losses in wheat production. Developing resistancevarieties is the most economical, effective and environmentally safe way to control thisdisease. And new resistance genes are the basis of crop breeding. Rye( Secale cereale L.)is the close sib plant of wheat, and it involves rich gene pools that can be used to improvethe resistance, production, quality and environmental toleration of wheat in breedingprogram. The 1RS/1BL translocation lines which carry Yr9, Pm8, Lr29, Sr31 and canimprove production, environmental toleration, are common used in wheat breeding all overthe world.Identification of translocaton lines is a difficult task to crop breeders. It is necessary touse several methods to identify translocation lines containing the alien chromatin,especially the small-segment translocation lines. The advanced progeny lines (BC₂F₆) fromthe monosomic addition lines between common wheat cultivar Mianyang 11(highsusceptible to stripe rust) and an inbred rye line R3(immune to stripe rust) were analyzedfor wheat-rye translocations. A series of measures, such as chromosome karyotype analysis,meiosis pairing analysis, A-PAGE, C-banding and GISH, were taken to detect the ryechromatin contained in the wheat background. Results were shown as follows:1. Resistance identification showed that 734 was immune to stripe rust and itsresistance inheritance is highly stable. While the control Mianyang 11 showed highsusceptible to stripe rust. It showed that rye chromatins might be introduced to 734 andstripe rust-resistant gene of 734 was from rye.2. Chromosome karyotype analysis showed that chromosome number of 734 was 42,and 21 bivalents could be observed at PMC MI by meiosis pairing analysis. It proved that734 is stable in genetics.3. The C-banding analysis demonstrated that the line 734 had no whole arm of ryechromosomes that can be idendified by C-banding. But it can not be sure whether therewere small segments of rye chromosomes.4. 734 was found to contain Gld1B3 locus by A-PAGE. It was determined that small1R chromosome segments carrying stripe rust-resistant and See-1 genes were translocatedto common wheat.5. The result of genomic in situ hybridization (GISH) revealed that small chromosome segments of rye were translocated to the terminal region of the short arm of one pair ofwheat chromosomes in 734.6. Qualities analysis revealed that protein and wet gluten content of 734 were up to16.7% and 37.3% respectively. And some of its agronomy traits meet the needs of wheatbreeding.The research showed that a new gene resistant to stripe rust which was from 1Rchromosome short arm of rye had translocated to 734. 734 is a novel small segmentstranslocation. Its inheritance is highly stable and therefore can be utilized as a finegermplasm of disease resistance in wheat breeding.