Gene Cloning and Characterization - Genetics, Genomics and Breeding of Crop Plants - page 181

Figure 6-1 Map-based cloning approach. A, Chromosome Landing; B, Chromosome
Walking.
6.2.1 Male Sterility and Fertility Restoration
Male sterility represents a phenotype in plants, in which the function of the
male gametophyte is prevented without affecting the female counterpart.
On the basis of inheritance patterns, two types of male sterility occur in
sunflower: nuclear male sterility (NMS) and cytoplasmic male sterility (CMS).
NMS is generally a result of a single homozygous recessive locus, and
after crossing with any fertile genotype an NMS line produces F 1 progenies
that are all male fertile (Jan 1997). Allelic relationships among NMS genes
have been reported by Vranceanu (1970). He tested for allelism in 10 NMS
sources isolated from a Romanian germplasm and reported the presence of
five independent NMS genes, named as Ms1 to Ms5 . Jan and Rutger (1988)
evaluated the effectiveness of seven NMS mutants induced by mitomycin-C
and streptomycin from the cultivated line HA89, which were confirmed
and placed in four different allelic groups, each representing a unique NMS
gene, designated Ms6 - Ms9 (Jan 1992). NMS genes from two released male
sterile lines, P21 and B11A3, have been designated Ms10 and Ms11 (Jan
1992), and were subsequently located on the sunflower genetic map by
Pérez-Vich et al. (2005). Ms10 mapped together with the gene T , an
anthocyanin pigment locus, to the linkage group (LG) 11, while Ms11 mapped
to the LG 8. Four simple sequence repeat (SSR) markers (ORS697, ORS1214,