A ISSR Molecular Marker For The Leaf Rust Resistance Gene Lr37 In Wheat

Inter-Simple Sequence Repeat (ISSR) analysis was carried out in Thatcher, near-isogenic lines carrying twenty-one different genes conferring resistance against leaf rust, three varieties containing Lr37 and three varieties without Lr37. The main results were as follows:1. The optimized ISSR reaction system was established. The system had a total volume of 25 u I, containing 10 mM KG, 8 mM(NH4)2S04, 10 mM Tris-HCI(pH- 9.0), NP-40, 2.0 mM Mg2\ 150u M dNTP, 200 nm primer, 60 ng template DNA, 2.0U Taq DNA polymerase. Amplification performed in a AmpGene DNA Thermal Cycler 4800 was programmed for 3 min at 94'C, 40 cycles of 30s at 94'C, 60s at 48'C, 90s at 72'C, and a final extention at 72'C for? min after the last cycle.2. One polymorphic ISSR marker (UBC812-1200) linked to leaf rust resistance gene Lr37 was screened. All of the 100 random primers screened for ISSR analysis gave clear amplification products, Twe of them amplified the polymorphic DNA in the NILs Thatcher and Lr37l6 Thatcher. The polymorphic bands were named as UBC812-1200 and UBC848-700, respectively. Using these two primers to detect three resistant materials containing Lr37 and other three susceptible materials without Lr37. It was shown that only UBC812-1200 band was amplified in all resistant material and absent in all of the susceptible materials. This suggested that the marker UBC812-1200 was linked to resistant gene Lr37. The genetic linkage of the polymorphic marker with Lr37 was tested of a segregating F2 population (128 plants) derived from a cross between the leaf rust resistant "Lr3 7/6*Thatcher" and the susceptible cultivar "Thatcher".One of the two ISSR markers (UBC812-1200) showed cosegregation to the Lr37 resistance gene.