Dissection of the barley 2L1.0 region carrying the 'Laevigatum' quantitative resistance gene to leaf rust using near-isogenic lines (NIL) and subNIL
Dissection of the barley 2L1.0 region carrying the 'Laevigatum' quantitative resistance gene to leaf rust using near-isogenic lines (NIL) and subNIL
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DOI：
10.1094/mpmi-20-12-1604
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发表时间：
2007-12-01
影响因子：
3.5
通讯作者：
Niks, Rients E.
中科院分区：
文献类型：
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作者：
Marcel, Thierry C.;Aghnoum, Reza;Niks, Rients E.
大麦对叶锈病的部分抗性是一种数量抗性，不是基于超敏性。这种抗性阻碍了吸器的形成，导致温室试验中的潜伏期长。通过标记辅助回交，将L94 x“Vada”定位群体中发现的3个最一致的数量性状位点（QTL）渗入易感L94背景，获得近等基因系（NIL）。我们还开发了这些QTL易感等位基因的互反Vada-NIL。与Rphq3和Rphq4相比，QTL Rphq2对褐家鼠潜伏期的影响更大。NIL通过延长L94-Rphq2的潜伏期28个It，缩短Vada-rphq2的潜伏期23个It，证实了Rphq2对部分耐药的贡献。基于侧翼限制性片段长度多态性的标记显示，Rphq2位于211染色体长臂端粒末端附近，处于高重组的物理区域，是定位克隆的目标QTL。对NIL的显微镜观察证实了Rphq2赋予的抗性的非超敏性。利用Vada背景中38个重叠L94基因渗入的subNIL群体构建了Rphq2区域的高分辨率遗传图谱。Rphq2在MlLa位点近端约2厘米处定位。通过大量分离分析和利用与水稻的同源性，我们开发了额外的标记，并将Rphq2精细定位到0.11 cM的遗传区间，该区间对应水稻中最多70 kb的序列。对该水稻序列的分析显示，预测基因编码两种功能未知的蛋白，反转录转座子蛋白、过氧化物酶蛋白和一种类似于丝裂原活化蛋白激酶激酶（MAP3K）的蛋白。这些过氧化物酶和MAP3K在大麦中可能的同源物是导致对小麦黑斑孢杆菌部分抗性的候选基因。
Partial resistance to leaf rust (Puccinia hordei G. H. Otth) in barley is a quantitative resistance that is not based on hypersensitivity. This resistance hampers haustorium formation, resulting in a long latency period in greenhouse tests. The three most consistent quantitative trait loci (QTL) uncovered in the L94 x 'Vada' mapping population were introgressed by marker-assisted backcrossing into the susceptible L94 background to obtain near-isogenic lines (NIL). We also developed the reciprocal Vada-NIL for the susceptibility alleles of those QTL. The QTL Rphq2 affected latency period of P. hordei more than the QTL Rphq3 and Rphq4. The NIL confirmed the contribution of Rphq2 to partial resistance by prolonging the latency period by 28 It on L94-Rphq2 and shortening the latency period by 23 It on Vada-rphq2. On the basis of flanking restriction fragment length polymorphism-based markers, Rphq2 appeared to be located near the telomeric end of the long arm of chromosome 211, in a physical region of high recombination, making it the target QTL for map-based cloning. Microscopic observations on the NIL confirmed the nonhypersensitive nature of the resistance conferred by Rphq2. A high-resolution genetic map of the Rphq2 region was constructed using a population of 38 subNIL with overlapping L94 introgressions in Vada background across the region. Rphq2 mapped approximatelly 2 centimorgans (cM) proximal from the MlLa locus. By bulked segregant analysis and use of synteny with rice, we developed additional markers and fine-mapped Rphq2 to a genetic interval of 0.11 cM that corresponds to a stretch of sequence of, at most, 70 kb in rice. Analysis of this rice sequence revealed predicted genes encoding two proteins with unknown function, retrotransposon proteins, peroxidase proteins, and a protein similar to a mitogen-activated protein kinase kinase kinase (MAP3K). Possible homologs of those peroxidases and MAP3K in barley are candidates for the gene that contributes to partial resistance to P. hordei.