Improving Blast Resistance Of Xiangwanxian 13 By Molecular Marker-assisted Selection Of Pigm Gene

Rice blast is one of the most destructive diseases that affects rice production.In this study,the indica rice variety Xiangwanxian13 was used as the receptor parent,and the blast resistant rice variety Gumei4,harboring the broad-spectrum durable blast resistance gene Pigm,was used as the donor parent,for improving blast resistance of Xiangwanxian13 by molecular marker-assisted selection.Main results are as follows:1.twenty-one Magnaporthe oryzae strains from different countries or regions were used to carry out indoor inoculation assay on four rice materials,Xiangwanxiang13,Gumei4,75-1-127（carrying broad-spectrum durable rice blast resistance gene Pi9,disease-resistant control）and CO39（disease-susceptible control）.The results showed that the resistance frequency of Gumei4 reached 95.2%,and Xiangwanxian13 was 61.9%.The resistance frequency of 75-1-127 was 85.7%,while CO39 was zero.At the same time,the results of the field nursery blast resistance investigation indicated that Xiangwanxian13 showed high susceptibility both of seedling blast and spike blast,and Gumei4 showed high resistance both of seedling blast and spike blast.These results indicated that the Pigm gene is feasible for blast resistance improvement of Xiangwanxian13.2.A Pigm-tightly-linked co-dominant In Del marker T9E4（F:5’-CAGAGCAGT AACAAACCCTA-3’;R:5’-TCCGCAAGATCAACA TTC-3’）was screened.This marker can amplify a 750 bp bright DNA band from the genome of Gumei4,while produced a 1800bp band from that of Xiangwanxian13.In order to verify the efficiency of T9E4 in backcross selection,the BC₅F₂ population of Xiangwanxian13×Gumei4 was investigated for both of marker genotype and blast resistance phenotype.Results show that T9E4 marker-assisted selection efficiency was as high as 100%in this assay.3.Eight blast resistant rice lines with the generation of BC₅F₅ were improved,from twelve BC₅F₂ individuals containing Pigm homozygous alleles identified by the marker T9E4.And three elite resistant rice lines were screened according to field agronomic and yield traits from above eight rice lines,named Xiangwanxian13-Pigm-671,Xiangwanxian13-Pigm-672 and Xiangwanxian13-Pigm-673 respectively.4.Rice quality analysis was carried out using the receptor parent Xiangwanxian13 and the three elite blast resistant lines,and Xiangwanxian13-Pigm-671 was screened for its complicated quality traits,which became the purpose rice line of this study for further developing novel rice variety.5.240 SSR markers covering different loci of rice 12 chromosomes were randomly selected from the gramene database,to analyze the genetic background difference of Xiangwanxian13-Pigm-671 and its receptor parent.The results showed that the genetic background recovery rate of Xiangwanxian13-Pigm-671 from Xiangwanxian13 was 93.75%,which was consistent with the results of agronomic traits,yield traits and rice quality traits assays.