Würschum Tobias, Leiser Willmar L, Weissmann Sigrid, Maurer Hans Peter
State Plant Breeding Institute, University of Hohenheim, 70593, Stuttgart, Germany.
HegeSaat GmbH & Co.KG, 78224, Singen-Bohlingen, Germany.
Theor Appl Genet. 2017 Jun;130(6):1253-1266. doi: 10.1007/s00122-017-2885-5. Epub 2017 Mar 21.
Restoration of fertility in the cytoplasmic male sterility-inducing Triticum timopheevii cytoplasm can be achieved with the major restorer locus Rf3 located on chromosome 1B, but is also dependent on modifier loci. Hybrid breeding relies on a hybrid mechanism enabling a cost-efficient hybrid seed production. In wheat and triticale, cytoplasmic male sterility based on the T. timopheevii cytoplasm is commonly used, and the aim of this study was to dissect the genetic architecture underlying fertility restoration. Our study was based on two segregating F triticale populations with 313 and 188 individuals that share a common female parent and have two different lines with high fertility restoration ability as male parents. The plants were cloned to enable replicated assessments of their phenotype and fertility restoration was evaluated based on seed set or staining for pollen fertility. The traits showed high heritabilities but their distributions differed between the two populations. In one population, a quarter of the lines were sterile, conforming to a 3:1 segregation ratio. QTL mapping identified two and three QTL in these populations, with the major QTL being detected on chromosome 1B. This QTL was collinear in both populations and likely corresponds to Rf3. We found that Rf3 explained approximately 30 and 50% of the genotypic variance, has a dominant mode of inheritance, and that the female parent lacks this locus, probably due to a 1B.1R translocation. Taken together, Rf3 is a major restorer locus that enables fertility restoration of the T. timopheevii cytoplasm, but additional modifier loci are needed for full restoration of male fertility. Consequently, Rf3 holds great potential for hybrid wheat and triticale breeding, but other loci must also be considered, either through marker-assisted or phenotypic selection.
位于1B染色体上的主要恢复基因座Rf3可实现诱导提莫菲维小麦细胞质雄性不育的育性恢复，但这也依赖于修饰基因座。杂交育种依赖于一种能实现经济高效杂交种子生产的杂交机制。在小麦和小黑麦中，基于提莫菲维小麦细胞质的细胞质雄性不育被广泛应用，本研究的目的是剖析育性恢复的遗传结构。我们的研究基于两个分离的小黑麦F群体，分别有313和188个个体，它们有共同的母本，且有两个具有高育性恢复能力的不同品系作为父本。对植株进行克隆以对其表型进行重复评估，并基于结实率或花粉育性染色来评估育性恢复情况。这些性状表现出较高的遗传力，但两个群体中的性状分布有所不同。在一个群体中，四分之一的品系不育，符合3:1的分离比。数量性状位点（QTL）定位在这些群体中分别鉴定出两个和三个QTL，其中主要的QTL在1B染色体上被检测到。该QTL在两个群体中是共线的，可能对应于Rf3。我们发现Rf3解释了约30%和50%的基因型变异，具有显性遗传模式，且母本缺乏该基因座，可能是由于1B.1R易位。综上所述，Rf3是使提莫菲维小麦细胞质育性恢复的主要恢复基因座，但要完全恢复雄性育性还需要其他修饰基因座。因此，Rf3在杂交小麦和小黑麦育种中具有巨大潜力，但也必须考虑其他基因座，可通过标记辅助选择或表型选择来实现。
