Molecular mapping of the Rf1 gene restoring pollen fertility in PET1-based F1 hybrids in sunflower (Helianthus annuus L.)

Abstract

Up to now a single cytoplasmic male sterility (CMS) source, PET1, is used worldwide for hybrid breeding in sunflower. Introgression of the restorer gene Rf1, responsible for fertility restoration, into new breeding material requires tightly linked markers to perform an efficient marker-assisted selection. A survey of 520 decamer primers by bulked segregant analyses identified five RAPD markers linked to the restorer gene Rf1. In a F(2) population of 183 individuals one of the RAPD markers, OPK13_454, mapped 0.8 cM from Rf1, followed by OPY10_740 with 2 cM. Bulked segregant analyses using 48 AFLP primer combinations identified 17 polymorphisms, which could be mapped in the same linkage group as Rf1. E33M61_136, and E41M48_113 were mapped 0.3 cM and 1.6 cM from the gene, respectively. Conversion of E41M48_113 into a sequence-specific marker resulted in a monomorphic pattern. However, two of the RAPD markers, OPK13_454 and OPY10_740, were successfully converted into SCAR markers, HRG01 and HRG02, which are now available for marker-assisted selection. To investigate the utility of these SCAR markers in other cross-combinations they were tested in a set of 20 lines. Comparison of the patterns of 11 restorer and nine maintainer lines of PET1 demonstrated that the markers OPK13_454/HRG01 and HRG02 were absent in all maintainer lines but present in all restorer lines, apart from the high oleic line RHA348 and the dwarf line Gio55. In addition, restorer lines developed from the interspecific hybrids Helianthus annuus x Helianthus mollis and H. annuus x Helianthus rigidus gave the same characteristic amplification products.

Study of informative DNA markers of the Rf1 gene in sunflower for breeding practice

“…Primers designed by Horn (Horn et al 2003) were used for the amplification of SCAR markers (HRG01 and HRG02)…”

“…Presently, the industrial production of sunflower seeds is based upon use of highly productive interlinear hybrids. The production of such hybrids involves a genetic system of plant pollination control, which includes maternal lines carrying genes of cytoplasmic male sterility (CMS) and paternal lines having the fertility restorer (Rf) genes (Horn et al 2003). Marking of the fertility recovering genes is important for precise selection of the carriers of dominant and recessive alleles of the Rf genes among separated populations.…”

“…This significantly accelerates the obtainment of parental forms of hybrids. Thus, the investigations of markers tightly linked with Rf genes are held worldwide, for example, several Rf genes markers were identified in maize (Zhang et al 2006), sunflower (Horn et al 2003), soya (Dong et al 2012), barley (Ui et al 2015) etc.…”

“…It was shown that CMS in sunflower is caused by 5000 bp insertion, which occurs on the border with the atpA gene and forms a new open reading frame orfH522 (Horn et al 1991). Nuclear Rf genes are responsible for polyadenylation of the atpA-orfH522 transcript that makes it accessible for RNase II and eventually leads to the restoration of pollen fertility (Horn et al 2003).…”

“…According to the published data, a large number of DNA markers of the 13 th linkage group were linked with Rf1 loci of sunflower: ORS 511, ORS 224, ORS 317, ORS 630, ORS 799, ORS 1030 (Tang et al 2002), HRG01, HRG02 (Horn et al 2003) and STS-115 (Yue et al 2010). Thus the Rf1 gene was mapped on the 13 th linkage group (Tang et al 2002).…”