Positional cloning of the rice Rf-1 gene, a restorer of BT-type cytoplasmic male sterility that encodes a mitochondria-targeting PPR protein
Positional cloning of the rice Rf-1 gene, a restorer of BT-type cytoplasmic male sterility that encodes a mitochondria-targeting PPR protein
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DOI：
10.1007/s00122-004-1591-2
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发表时间：
2004-05-01
影响因子：
5.4
通讯作者：
Fujimura, T
中科院分区：
文献类型：
--
作者：
Akagi, H;Nakamura, A;Fujimura, T
将一个亲本的细胞质雄性不育（CMS）和另一个亲本的恢复基因（Rf）结合起来，以恢复育性，是培育杂交种所不可缺少的。我们已经发现了一个水稻Rf-1基因，恢复BT型CMS应用定位克隆策略。利用连锁分析结合6,104 BC 1F 3后代来自两个近等基因系（NILs）之间的杂交，不同的只是在Rf-1位点，我们划定Rf-1基因在水稻基因组中的22.4 kb的区域。在该区域发现了具有五肽（PPR）基序的重复开放阅读框架（Rf-1A和Rf-1B）。由于在保持系的等位基因中与Rf-1A和Rf-1B基因对应的区域中发现了几个插入和/或缺失，它们可能已经失去了功能。Rf-1A蛋白具有靶向信号，而Rf-1B没有。Rf-1B基因编码由提前终止密码子决定的较短多肽。基于Rf-1基因的功能，预期其产物靶向线粒体，并可加工来自线粒体基因组中的atp 6/orf 79区域的转录物。由于Rf-1A基因编码一个791个氨基酸的蛋白质，具有靶向线粒体的信号，并具有16个重复的PPR基序，我们得出结论，Rf-1A是Rf-1基因。在日本晴基因组的Rf-1位点周围发现了9个重复的Rf-1A同源物。然而，虽然它们中的一些编码具有PPR基序的蛋白质，但它们不能基于与恢复表型缺乏共分离来恢复BT型CMS。在这些基因和线粒体基因组的共同进化过程中，这些重复可能在线粒体中的RNA加工和/或重组中发挥了多种作用。
The combination of cytoplasmic male sterility (CMS) in one parent and a restorer gene (Rf) to restore fertility in another are indispensable for the development of hybrid varieties. We have found a rice Rf-1 gene that restores BT-type CMS by applying a positional cloning strategy. Using linkage analysis in combination with 6,104 BC1F3 progeny derived from a cross between two near-isogenic lines (NILs) differing only at the Rf-1 locus, we delimited the Rf-1 gene to a 22.4-kb region in the rice genome. Duplicate open reading frames (Rf-1A and Rf-1B) with a pentatricopeptide (PPR) motif were found in this region. Since several insertions and/or deletions were found in the regions corresponding to both the Rf-1A and Rf-1B genes in the maintainer's allele, they may have lost their function. Rf-1A protein had a mitochondria-targeting signal, whereas Rf-1B did not. The Rf-1B gene encoded a shorter polypeptide that was determined by a premature stop codon. Based on the function of the Rf-1 gene, its product is expected to target mitochondria and may process the transcript from an atp6/orf79 region in the mitochondrial genome. Since the Rf-1A gene encodes a 791-amino acid protein with a signal targeting mitochondria and has 16 repeats of the PPR motif, we concluded that Rf-1A is the Rf-1 gene. Nine duplications of Rf-1A homologs were found around the Rf-1 locus in the Nipponbare genome. However, while some of them encoded proteins with the PPR motif, they do not restore BT-type CMS based on the lack of co-segregation with the restoration phenotype. These duplicates may have played diversified roles in RNA processing and/or recombination in mitochondria during the co-evolution of these genes and the mitochondrial genome.