Heterochromatic and genetic features are consistent with recombination suppression of the self-incompatibility locus in Antirrhinum.
Self-incompatibility (SI) is a genetic mechanism to prevent self-fertilization that is found in many species of flowering plants. Molecular studies have demonstrated that the S-RNase and SLF/SFB genes encoded by the single polymorphic S locus, which control the pollen and pistil functions of SI in three distantly related families, the Solanaceae, Scrophulariaceae and Rosaceae, are organized in a haplotype-specific manner. Previous work suggested that the haplotype structure of the two genes is probably maintained by recombination suppression at the S locus. To examine features associated with this suppression, we first mapped the S locus of Antirrhinum hispanicum, a member of the Scrophulariaceae, to a highly heterochromatic region close to the distal end of the short arm of chromosome 8. Both leptotene chromosome and DNA fiber fluorescence in situ hybridization analyses showed an obvious haplotype specificity of the Antirrhinum S locus that is consistent with its haplotype structure. A chromosome inversion was also detected around this region between A. majus and A. hispanicum. These results revealed that DNA sequence polymorphism and a heterochromatic location are associated with the S locus. Possible roles of these features in maintenance of the haplotype specificity involved in both self and non-self recognition are discussed.
Yang
Qiuying
Q
Laboratory of Molecular and Developmental Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences and National Center for Plant Gene Research, Beijing 100101, China.
Zhang
Dongfen
D
Li
Qun
Q
Cheng
Zhukuan
Z
Xue
Yongbiao
Y
D032161:Antirrhinum / Q000166:cytology / Q000235:genetics*; D007446:Chromosome Inversion; D002874:Chromosome Mapping; D022201:Chromosomes, Artificial; D005298:Fertility / Q000235:genetics; D017343:Genes, Plant; D006239:Haplotypes; D006570:Heterochromatin; D017404:In Situ Hybridization, Fluorescence; D007178:Inbreeding; D049471:Pachytene Stage; D011995:Recombination, Genetic; D012260:Ribonucleases / Q000235:genetics
D006570:Heterochromatin; D012260:Ribonucleases