Abstract：
BACKGROUND: Bacterial blight, caused by Xanthomonas oryzae pv. oryzae (Xoo), is one of the most devastating diseases of rice leading to huge yield losses in Southeast Asia. The recessive resistance gene xa-45(t) from Oryza glaberrima IRGC102600B, mapped on rice chromosome 8, spans 80 Kb with 9 candidate genes on Nipponbare reference genome IRGSP-1.0. The xa-45(t) gene provides durable resistance against all the ten Xanthomonas pathotypes of Northern India, thus aiding in the expansion of recessive bacterial blight resistance gene pool. Punjab Rice PR127, carrying xa-45(t), was released for wider use in breeding programs. This study aims to precisely locate the target gene among the 9 candidates conferring resistance to bacterial blight disease.
RESULTS: Sanger sequencing of all nine candidate genes revealed seven SNPs and an Indel between the susceptible parent Pusa 44 and the resistant introgression line IL274. The genotyping with polymorphic markers identified three recombinant breakpoints for LOC_Os08g42370, and LOC_Os08g42400, 15 recombinants for LOC_Os08g423420 and 26 for LOC_Os08g42440 out of 190 individuals. Relative expression analysis across six time intervals (0, 8, 24, 48, 72, and 96 h) after bacterial blight infection showed over expression of LOC_Os08g42410-specific transcripts in IL274 compared to Pusa 44, with a significant 4.46-fold increase observed at 72 h post-inoculation.
CONCLUSIONS: The Indel marker at the locus LOC_Os08g42410 was found co-segregating with the phenotype, suggesting its candidacy towards xa-45(t). The transcript abundance assay provides strong evidence for the involvement of LOC_Os08g42410 in the resistance conferred by the bacterial blight gene xa-45(t).
RESULTS: Sanger sequencing of all nine candidate genes revealed seven SNPs and an Indel between the susceptible parent Pusa 44 and the resistant introgression line IL274. The genotyping with polymorphic markers identified three recombinant breakpoints for LOC_Os08g42370, and LOC_Os08g42400, 15 recombinants for LOC_Os08g423420 and 26 for LOC_Os08g42440 out of 190 individuals. Relative expression analysis across six time intervals (0, 8, 24, 48, 72, and 96 h) after bacterial blight infection showed over expression of LOC_Os08g42410-specific transcripts in IL274 compared to Pusa 44, with a significant 4.46-fold increase observed at 72 h post-inoculation.
CONCLUSIONS: The Indel marker at the locus LOC_Os08g42410 was found co-segregating with the phenotype, suggesting its candidacy towards xa-45(t). The transcript abundance assay provides strong evidence for the involvement of LOC_Os08g42410 in the resistance conferred by the bacterial blight gene xa-45(t).
摘要：
背景：细菌性疫病，由米黄单胞菌pv引起。稻米（Xoo），是导致东南亚产量损失的最具破坏性的水稻疾病之一。水稻IRGC102600B隐性抗性基因xa-45(t),定位在水稻8号染色体上，跨越80Kb，在Nipponbare参考基因组IRGSP-1.0上具有9个候选基因。xa-45（t）基因对印度北部的所有十种黄单胞菌致病型提供了持久的抗性，从而有助于隐性白叶枯病抗性基因库的扩大。旁遮普大米PR127，携带xa-45（t），已发布用于育种计划中的更广泛使用。本研究旨在在赋予细菌性白叶枯病抗性的9个候选物中精确定位目标基因。
结果：所有9个候选基因的Sanger测序揭示了易感亲本Pusa44和抗性基因渗入系IL274之间的7个SNP和一个Indel。用多态性标记进行的基因分型在190个个体中确定了LOC_Os08g42370和LOC_Os08g42400的三个重组断点，LOC_Os08g423420的15个重组子和LOC_Os08g42440的26个重组子。细菌疫病感染后六个时间间隔（0、8、24、48、72和96小时）的相对表达分析显示，与Pusa44相比，IL274中的LOC_Os08g42410特异性转录物过度表达，接种后72小时观察到显着的4.46倍增加。
结论：发现在LOC_Os08g42410基因座处的Indel标记与表型共分离，建议其候选xa-45(t)。转录物丰度测定为LOC_Os08g42410参与细菌疫病基因xa-45(t)赋予的抗性提供了强有力的证据。
结果：所有9个候选基因的Sanger测序揭示了易感亲本Pusa44和抗性基因渗入系IL274之间的7个SNP和一个Indel。用多态性标记进行的基因分型在190个个体中确定了LOC_Os08g42370和LOC_Os08g42400的三个重组断点，LOC_Os08g423420的15个重组子和LOC_Os08g42440的26个重组子。细菌疫病感染后六个时间间隔（0、8、24、48、72和96小时）的相对表达分析显示，与Pusa44相比，IL274中的LOC_Os08g42410特异性转录物过度表达，接种后72小时观察到显着的4.46倍增加。
结论：发现在LOC_Os08g42410基因座处的Indel标记与表型共分离，建议其候选xa-45(t)。转录物丰度测定为LOC_Os08g42410参与细菌疫病基因xa-45(t)赋予的抗性提供了强有力的证据。
