Evaluation Of Nine Blast Resistance Genes Through Natural Infection And Its Breeding Analysis In Rice

Developing resistant cultivars is the most eco-friendly and sustainable way to manage rice blast.In this study,9 cloned broad-spectrum blast resistance genes Pi37,Pit,Pid3,Pigm,Pi36,Pi5,Pikh,Pikm and Pb1,were respectively introgressed into Y58 S,Guangzhan63-4S(GZ63-4S),C815 S and HD9802 S,four photo-thermo-sensitive genic male sterile lines(PTGMS),based on molecular marker-assisted selection and backcross breeding.Furthermore,the broad-spectrum resistance of new versions of PTGMS were comprehensively evaluated in the natural blast disease nursery.The results are as follows:1.31 single-gene and 22 double-gene improved lines(ILs)were obtained,all the plants were scored for leaf blast at tillering stages and neck blast at maturity stage.2.Comparison of resistance performance of the improved lines and their PTGMS in natural infection,we found the plants with Pid3 showed extremely remarkable(P<0.01)blast resistance improvement at the whole growth period under 4 sterile line backgrounds for two years;Pigm showed extremely remarkable or remarkable(P<0.05)resistance improvement for leaf blast at tillering stages and neck blast at maturity stage in all 4sterile lines,except the leaf blast at tillering stages under C815 S and HD9802 S in 2014 and GZ63-4S in 2015.Pikh,Pi5 and Pi37 showed the similar genetic effect to Pigm,but the resistance were unstable;Pi36 and Pit only showed blast resistance improvement under few backgrounds;Pikm showed extremely remarkable resistance improvement for leaf blast at tillering stages but no resistance for neck blast at maturity stage;The blast resistance of Pb1 was undetected because of significantly less population.3.Compared with recurrent parents,most of the double-gene lines showed remarkable resistance development.Such as lines with Pi37/Pigm,Pid3/Pikh,Pigm/Pid3 and Pi5/Pikh exhibited remarkable resistance development and obvious additive effect,however,like lines with Pi37/Pikh or Pit/Pigm show no additive effect.In our study,the 9 genes and their combinations of different genotypes for blast resistance in the 4 sterile lines have been evaluated in natural infection,holds important value for rice blast breeding.