Molecular mapping of nuclear male sterility genes in sunflower

Nuclear male sterility (NMS) is a useful tool for sunflower (Helianthus annuus L.) breeding and genetics programs. A clear understanding of the genetics of NMS at the molecular level and the identification of linked molecular markers will greatly facilitate breeding for this trait. P21 is an inbred line carrying the single gene Ms-11 controlling NMS, and NMS801 and NMS373 are two inbred lines with the NMS gene Ms-10. The objectives of this study were to (i) identify molecular markers linked with the Ms10 and the Ms-11 NMS genes, and (ii) place these genes on the genetic map of sunflower. Three F-2 and a BC1F1 mapping populations developed from crosses between the male-sterile (MS) lines P21, NMS801, and NMS373, and male-fertile (MF) (wildtype) lines were scored for fertility/sterility. The NMS801 and NMS373 populations segregated for Ms-10 and T, a tightly linked anthocyanin pigment locus. The P21 populations segregated for Ms-10. These populations were then genotyped with restriction fragment length polymorphism (RFLP), simple sequence repeat or microsatellite (SSR), and insertion-deletion polymorphism (INDEL) markers, and four genetic maps comprising 14 to 17 linkage groups (LGs) were constructed for each population. The Ms-10 and T genes mapped to LG 11, while the Ms-11 gene mapped to LG 8. Four SSR markers (ORS697, ORS1214, ORS686, and CRT162) and the phenotypic marker locus T cosegregated and were tightly linked to Ms-10 at a genetic distance of less than 1 cM. The Ms-11 gene locus was flanked by the SSR markers MS925 and ORS536 at genetic distances of 3.8 and 4.1 cM, respectively. The availability of tightly linked polymerase chain reaction based markers and the location of NMS genes on the sunflower genetic map will be useful for marker-assisted selection (MAS) in sunflower breeding programs and provides a basis for the physical mapping and positional cloning of these genes.