Background

Field resistance is often effective and durable as compared to vertical resistance. The introgression line (INGR15002) derived from O. glumaepatula has proven broad spectrum field resistance for both leaf and neck blast.

Results

Quantitative Trait Loci (QTL) analysis of INGR15002, led to the identification of two major QTL - qBL3 contributing about 34% and 32% phenotypic variance towards leaf and neck blast resistance, respectively and qBL7 contributing about 25% of phenotypic variance for leaf blast. Further, qBL3 was fine mapped, narrowed down to 300 kb region and a linked SNP maker was identified. By combining mapping with microarray analysis, a candidate gene, Os03g0281466 (malectin-serine threonine kinase), was identified in the fine mapped region and named as Pi68(t). The nucleotide variations in the coding as well as upstream region of the gene was identified through cloning and sequence analysis of Pi68(t) alleles. These significant variations led to the non-synonymous changes in the protein as well as variations (presence/absence) in four important motifs (W-box element; MYC element; TCP element; BIHD1OS) at promoter region those are associated with resistance and susceptible reactions. The effect of qBL3 was validated by its introgression into BPT5204 (susceptible variety) through marker-assisted selection and progeny exhibiting resistance to both leaf and neck blast was identified. Further, the utility of linked markers of Pi68(t) in the blast breeding programs was demonstrated in elite germplasm lines.

Conclusions

This is the first report on the identification and characterization of major effect QTL from O. glumaepatula, which led to the identification of a putative candidate gene, Pi68(t), which confers field resistance to leaf as well as neck blast in rice.

中文翻译：

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水稻稻瘟病抗性候选基因Pi68（t）揭示的稻瘟病大效QTL的鉴定与鉴定

背景

与垂直电阻相比，场电阻通常是有效且持久的。源自小鳞翅目（O. glumaepatula）的渗入系（INGR15002）已证明对叶和颈部胚芽均具有广谱抗性。

结果

INGR15002的定量性状基因座（QTL）分析导致鉴定出两个主要QTL-qBL3分别对叶和颈部稻瘟病抗性贡献约34％和32％的表型变异，而qBL7对叶瘟的表型变异贡献约25％。此外，qBL3进行了精细定位，缩小到300 kb区域，并确定了一个连锁SNP制造商。通过将定位与微阵列分析相结合，在精细定位区域中鉴定了一个候选基因Os03g0281466（malectin-丝氨酸苏氨酸激酶），并将其命名为Pi68（t）。通过对Pi68（t）等位基因的克隆和序列分析，鉴定了基因编码区和上游区的核苷酸变异。这些显着的变异导致蛋白质的非同义变化以及启动子区域的四个重要基序（W-box元件； MYC元件； TCP元件； BIHD1OS）的变异（存在/不存在），这些变异与抗性和易感性有关。反应。通过标记辅助选择将qBL3渗入BPT5204（易感品种）中，从而验证了qBL3的作用，并鉴定了对叶和颈部胚芽均具有抗性的后代。此外，在优良种质系中证明了Pi68（t）连锁标记在blast育种程序中的效用。通过标记辅助选择将qBL3渗入BPT5204（易感品种）中，从而验证了qBL3的作用，并鉴定了对叶和颈部胚芽均具有抗性的后代。此外，在优良种质系中证明了Pi68（t）的连锁标记在blast育种程序中的效用。通过标记辅助选择将qBL3渗入BPT5204（易感品种）中，从而验证了qBL3的作用，并鉴定了对叶和颈部胚芽均具有抗性的后代。此外，在优良种质系中证明了Pi68（t）连锁标记在blast育种程序中的效用。

结论

这是关于鉴定和鉴定来自O. glumaepatula的主要效应QTL的第一份报告，该报告导致鉴定了一个推定的候选基因Pi68（t），该基因赋予了田间对水稻叶片和颈部稻瘟病的抗性。