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 Ms 10 and the Ms 11 NMS genes, and (ii) place these genes on the genetic map of sunflower. Three F 2 and a BC 1 F 1 mapping populations developed from crosses between the male-sterile (MS) lines P21, NMS801, and NMS373, and male-fertile (MF) (wild-type) 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 11 . 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.