Abstract
BackgroundRice (Oryza sativa) bacterial leaf blight (BLB), caused by the hemibiotrophic Xanthomonas oryzae pv. oryzae (Xoo), is one of the most devastating diseases affecting the production of rice worldwide. The development and use of resistant rice varieties or genes is currently the most effective strategy to control BLB.ResultsHere, we used 259 rice accessions, which are genotyped with 2 888 332 high-confidence single nucleotide polymorphisms (SNPs). Combining resistance variation data of 259 rice lines for two Xoo races observed in 2 years, we conducted a genome-wide association study (GWAS) to identify quantitative trait loci (QTL) conferring plant resistance against BLB. The expression levels of genes, which contains in GWAS results were also identified between the resistant and susceptible rice lines by transcriptome analysis at four time points after pathogen inoculation. From that 109 candidate resistance genes showing significant differential expression between resistant and susceptible rice lines were uncovered. Furthermore, the haplotype block structure analysis predicted 58 candidate genes for BLB resistance based on Chr. 7_707158 with a minimum P-value (–log 10 P = 9.72). Among them, two NLR protein-encoding genes, LOC_Os07g02560 and LOC_Os07g02570, exhibited significantly high expression in the resistant line, but had low expression in the susceptible line of rice.ConclusionsTogether, our results reveal novel BLB resistance gene resources, and provide important genetic basis for BLB resistance breeding of rice crops.
Highlights
Rice (Oryza sativa) bacterial leaf blight (BLB), caused by the hemibiotrophic Xanthomonas oryzae pv. oryzae (Xoo), is one of the most devastating diseases affecting the production of rice worldwide
Rice production worldwide is severely threatened by bacterial leaf blight (BLB), a plant disease caused by Xanthomonas oryzae pv. oryzae (Xoo) [2]
Because BLB spreads rapidly, such chemical control applied in a monsoon climate is unpractical, since once a BLB infestation occurs on a large scale, its effective control by pesticides is difficult if not impossible [8]
Summary
Rice (Oryza sativa) bacterial leaf blight (BLB), caused by the hemibiotrophic Xanthomonas oryzae pv. oryzae (Xoo), is one of the most devastating diseases affecting the production of rice worldwide. Rice production worldwide is severely threatened by bacterial leaf blight (BLB), a plant disease caused by Xanthomonas oryzae pv. Xoo is prevalent in ricegrowing areas of world, but due to its host-shifting capacity, this bacterium threatens wheat production in both south America and Asia [3, 4]. Damage from this disease has led to rice production losses of 20%–30%, reaching devastating levels of up to 80%–90% in India and Philippines [5, 6]. The easiest way to prevent BLB is to apply chemical pesticides; large-scale use of a variety of pesticides threatens the safety of rice food products. Developing and applying resistant rice cultivars is the most effective way to control this disease and ensure food security
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