Abstract
BackgroundRice blast caused by Magnaporthe oryzae is the most devastating disease in rice production. Compared with seedling blast, panicle blast is considered to be more destructive, which can occur without being preceded by severe seedling blast. However, panicle blast resistance research is rarely reported.ResultsBodao, a japonica landrace from Taihu Lake region, showed a high level of panicle blast resistance. In this study, a mapping population of 212 recombination inbreeding lines (RILs) was developed from a cross of Bodao and the susceptible cultivar Suyunuo, and the RILs were evaluated for panicle blast resistance in three trials. Two quantitative trait loci (QTLs) qPb11–1 and qPb6–1 for panicle-blast resistance were identified, including a major QTL qPb11–1 (Pb-bd1) on chromosome 11 of Bodao explaining from 55.31% to 71.68% of the phenotype variance, and a minor QTL qPb6–1 on chromosome 6 of Suyunuo explaining from 3.54% to 6.98% of the phenotype variance. With the various segregation populations, Pb-bd1 was fine mapped in a 40.6 Kb region flanked by markers BS83 and BS98, and six candidate genes were identified within this region, including one gene encoding NAC domain-containing protein, one gene encoding unknown expression proteins, two genes encoding nucleotide binding site-leucine rich repeat (NBS-LRR) type disease resistance proteins, and two genes encoding von Willebrand factor type A (VWA) domain containing proteins. For application in rice breeding, three introgression lines of Pb-bd1with significantly enhanced panicle blast resistance were developed by using molecular assisted method (MAS) from the commercial variety Nanjing46 (NJ46).ConclusionTwo QTLs, qPb11–1(Pb-bd1) and qPb6–1 conferring panicle blast resistance, were identified from japonica landrace Bodao and Suyunuo.qPb11–1(Pb-bd1) was fine mapped in a 40.6 Kb region flanked by marker BS83 and BS98. Three introgression lines of Pb-bd1with significantly enhanced panicle blast resistance were developed by MAS method from the commercial variety NJ46. It indicated that Pb-bd1 would be useful gene source in panicle blast resistance breeding.
Highlights
Rice blast caused by Magnaporthe oryzae is the most devastating disease in rice production
Two quantitative trait loci (QTLs) identification of panicle blast resistance in Bodao A genetic map with total 1303.34 cM and average 14.98 cM between two adjacent SSR markers was constructed with 87 polymorphic SSR markers selected from 2257 SSR
Two panicle blast resistance QTLs qPb11–1 and qPb6–1 were identified by inclusive composite interval mapping (ICIM) method with phenotypic data from three trials at Nanjing and Lingshui in 2014, and Nanjing in 2015 (Table 3, Fig. 2)
Summary
Rice blast caused by Magnaporthe oryzae is the most devastating disease in rice production. Rice blast, caused by the fungal pathogen Magnaporthe oryzae, is one of the most devastating diseases worldwide, which can occur. The majority of cloned resistance genes encoded nucleotide binding site-leucine rich repeat (NBS-LRR) proteins (Chen et al 2010), except for Pi-d2 (encoding a B-lectin receptor kinase) (Kouzai et al 2013), recessive gene pi (encoding a proline-rich protein) (Fukuoka et al 2009), Bsr-d1 (encoding a C2H2-type transcription factor protein) (Li et al 2017), and Bsr-k1 (encoding a tetratricopeptide repeats-containing protein) (Zhou et al 2018). Pi-gmR confered broad-spectrum resistance, and Pi-gmS can increase rice production to counteract the yield lost caused by Pi-gmR. Li et al (2017) reported Bsr-d1 was an C2H2-type transcription factor conferring broad-spectrum blast resistance, and low expression of this gene could enhance disease resistance by inhibiting degradation of H2O2 Pi-gmR confered broad-spectrum resistance, and Pi-gmS can increase rice production to counteract the yield lost caused by Pi-gmR. Li et al (2017) reported Bsr-d1 was an C2H2-type transcription factor conferring broad-spectrum blast resistance, and low expression of this gene could enhance disease resistance by inhibiting degradation of H2O2
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