Instituto de Genética "Ewald A. Favret", CICVyA (Centro de Investigación en Ciencias Veterinarias y Agronómicas), INTA (Instituto Nacional de Tecnología Agropecuaria), Nicolás Repetto y de los Reseros s/n (1686), Hurlingham, Buenos Aires, Argentina.
Laboratorio de Agrobiotecnología, Grupo Biología Molecular Vegetal Aplicada, Instituto de Biodiversidad y Biología Experimental y Aplicada (IBBEA, CONICET-UBA), Departamento de Fisiología, Biología Molecular y Celular, Facultad de Ciencias Exactas y Naturales, UBA, Buenos Aires, Argentina.
Sci Rep. 2019 Jul 10;9(1):9960. doi: 10.1038/s41598-019-46321-6.
Previously, through a TILLING (Targeting Induced Local Lesions in Genomes) approach applied on barley chloroplast mutator (cpm) seedlings a high frequency of polymorphisms in the rpl23 gene was detected. All the polymorphisms corresponded to five differences already known to exist in nature between the rpl23 gene located in the inverted repeats (IRs) and the rpl23 pseudogene located in the large single copy region (LSC). In this investigation, polymorphisms in the rpl23 gene were verified and besides, a similar situation was found for the pseudogene in cpm seedlings. On the other hand, no polymorphisms were found in any of those loci in 40 wild type barley seedlings. Those facts and the independent occurrence of polymorphisms in the gene and pseudogene in individual seedlings suggest that the detected polymorphisms initially arose from gene conversion between gene and pseudogene. Moreover, an additional recombination process involving small recombinant segments seems to occur between the two gene copies as a consequence of their location in the IRs. These and previous results support the hypothesis that the CPM protein is a component of the plastome mismatch repair (MMR) system, whose failure of the anti-recombination activity results in increased illegitimate recombination between the rpl23 gene and pseudogene.
先前，通过应用于大麦叶绿体突变体（cpm）幼苗的 TILLING（靶向诱导基因组局部突变）方法，在 rpl23 基因中检测到了高频的多态性。所有的多态性都对应于已经在自然界中存在于位于反向重复（IRs）中的 rpl23 基因和位于大单一拷贝区（LSC）中的 rpl23 假基因之间的五个差异。在这项研究中，验证了 rpl23 基因中的多态性，并且在 cpm 幼苗中的假基因中也发现了类似的情况。另一方面，在 40 个野生型大麦幼苗的任何这些基因座中都没有发现多态性。这些事实以及基因和假基因在个体幼苗中独立发生的多态性表明，最初检测到的多态性是由基因和假基因之间的基因转换引起的。此外，由于它们位于 IRs 中，两个基因拷贝之间似乎发生了涉及小重组片段的额外重组过程。这些和以前的结果支持这样的假设，即 CPM 蛋白是质体错配修复（MMR）系统的一个组成部分，其抗重组活性的失败导致 rpl23 基因和假基因之间的非法重组增加。
