INRA Institut National de la Recherche Agronomique, UMR1318, IJPB Institut Jean-Pierre Bourgin, Versailles, France.
PLoS One. 2013 Apr 29;8(4):e62450. doi: 10.1371/journal.pone.0062450. Print 2013.
Gynodioecy, the coexistence of hermaphrodites and females (i.e. male-sterile plants) in natural plant populations, most often results from polymorphism at genetic loci involved in a particular interaction between the nuclear and cytoplasmic genetic compartments (cytonuclear epistasis): cytoplasmic male sterility (CMS). Although CMS clearly contributes to the coevolution of involved nuclear loci and cytoplasmic genomes in gynodioecious species, the occurrence of CMS genetic factors in the absence of sexual polymorphism (cryptic CMS) is not easily detected and rarely taken in consideration. We found cryptic CMS in the model plant Arabidopsis thaliana after crossing distantly related accessions, Sha and Mr-0. Male sterility resulted from an interaction between the Sha cytoplasm and two Mr-0 genomic regions located on chromosome 1 and chromosome 3. Additional accessions with either nuclear sterility maintainers or sterilizing cytoplasms were identified from crosses with either Sha or Mr-0. By comparing two very closely related cytoplasms with different male-sterility inducing abilities, we identified a novel mitochondrial ORF, named orf117Sha, that is most likely the sterilizing factor of the Sha cytoplasm. The presence of orf117Sha was investigated in worldwide natural accessions. It was found mainly associated with a single chlorotype in accessions belonging to a clade predominantly originating from Central Asia. More than one-third of accessions from this clade carried orf117Sha, indicating that the sterilizing-inducing cytoplasm had spread in this lineage. We also report the coexistence of the sterilizing cytoplasm with a non-sterilizing cytoplasm at a small, local scale in a natural population; in addition a correlation between cytotype and nuclear haplotype was detected in this population. Our results suggest that this CMS system induced sexual polymorphism in A. thaliana populations, at the time when the species was mainly outcrossing.
雌雄异熟，即在自然植物种群中雌雄同体和雌性（即雄性不育植物）共存，最常起因于涉及核和细胞质遗传成分之间特定相互作用的遗传位点的多态性（细胞质遗传上位性）：细胞质雄性不育（CMS）。虽然 CMS 明显有助于雌雄异熟物种中涉及核基因座和细胞质基因组的共同进化，但在不存在性多态性的情况下（隐性 CMS）发生 CMS 遗传因子不易被检测到，并且很少被考虑。我们在远缘杂交后在模式植物拟南芥中发现了隐性 CMS。雄性不育是由 Sha 细胞质和位于 1 号和 3 号染色体上的两个 Mr-0 基因组区域之间的相互作用引起的。通过与 Sha 或 Mr-0 杂交，从核不育保持系或不育细胞质的其他品系中鉴定出了附加品系。通过比较具有不同雄性不育诱导能力的两个非常密切相关的细胞质，我们鉴定出了一个新的线粒体 ORF，命名为 orf117Sha，它很可能是 Sha 细胞质的杀菌因子。在全世界的自然种群中研究了 orf117Sha 的存在。它主要与属于主要源自中亚的一个分支的种群中的单一叶绿素型相关联。来自该分支的三分之一以上的品系携带 orf117Sha，表明杀菌诱导细胞质在该谱系中传播。我们还报告了在一个自然种群中，在小的局部范围内同时存在杀菌细胞质和非杀菌细胞质；此外，在该种群中还检测到了细胞型和核单倍型之间的相关性。我们的结果表明，在该 CMS 系统中，当该物种主要是异花授粉时，在拟南芥种群中诱导了性多态性。
