Tagging And Mapping Of Maize (Zea Mays L.) Stalk Rot Resistance Gene (caused By Pythium Inflatum Malthews) With Molecular Markers

Stalk rot disease as one of the three major diseases in maize, occurs throughout the world. It also has become a major concern in China. Stalk rot disease (caused by Pythium inflatum Malthews) is of more economic concern due to a significant yield reduction caused by stalk lodging, premature death, reduced grain weight, and in some cases crop failure.The use of molecular markers allows one to study the maize inbred lines with stalk rot resistance gene. By screening polymorphism markers, the markers linked with the resistance gene will be found. Then the chromosome location of the gene can be determined. It is essential to practice MAS (marker assisted selection) in improving the efficiency of breeding, and even clone the resistance gene.In this study, a F2 population was derived from a cross of 1145 >( Y33 1, 1145 is the resistant parent, and Y33 I is the sensitive parent. Maize stalk rot pathogeny is Pythium inflatum Malthews. By the use of RAPD combined with the BSA (bulk segregation analysis), the markers linked with the maize stalk rot resistance gene (caused by Pythium inflatum Malthews) were found. The results as follows:1. From 520 Operon (10-mer) primer, 145 amplified polymorphism between two parents. Then BSA was performed, 40 primers can show polymorphism between the bulks. By the repeat and analysis, OPA04~ OPFO9 OPF1 50P116. OPRO5~, QPSO1 .. OPS08~ OPT12~ OPU10~ OPU16~. OPZ19 werefound to be linked with the maize stalk rot resistance gene(Rpil).2. RAPD analysis of F2 population (total 60 individuals) with the 11 polymorphic primers, indicated that OPZ 19~5QQ 0PR051033 0PA04880OPF091100~QPS08653 were linked with the maize stalk rot resistance gene Rpi]. The recombination between Rpi] and QPZ 19~ OPAO4 OPFO9 was 10 out of 60, 16.6%; 6 out of 60, 10% ; 5 out of 60, 8.3% respectively. OPRO5 and OPSO8 just screened the individuals combining the bulks. Further screening is needed.3. OPZ191500.~ OPR051Q33~ OPA04880~ OPF091100~ 0PS08653 0PU161000 , the6 specific fragments linked with Rpi], were cloned into pGEM?T Easy Vector, and then were used as probes in RFLP analysis. The results indicated that 0PA04880 was a medium copy sequence, and 0PR051033 and 0PU161000 were a repeated sequence. They all can not be mapped. 0PZ191500was a single copy sequence, it was used for mapping.4. Then the F, RILs population derived from the cross of S3 X Mol7 was usedto map OPZ19,,,,' the result indicated that f OPZl9,,,, is in the same linkagegroup with anch markers isul20, isu36, isu97, csu294, which have beenmapped on chromosome 4. Therefore OPZl9,,,, must be located onchromosome 4. RPii gene linked with OPZl9,,,,' therefore, it is onchromosome 4.5. ln this study, the maize stalk rot resistance gene (caused by Pythiumipfialum Malthews) was maPped and named RPii gene.