Sexual Plant Reproduction

, Volume 16, Issue 4, pp 165–177

Structural and transcriptional analysis of S-locus F-box genes in Antirrhinum

  • Junli Zhou
  • Fei Wang
  • Wenshi Ma
  • Yansheng Zhang
  • Bin Han
  • Yongbiao Xue
Original Article

DOI: 10.1007/s00497-003-0185-5

Cite this article as:
Zhou, J., Wang, F., Ma, W. et al. Sex Plant Reprod (2003) 16: 165. doi:10.1007/s00497-003-0185-5

Abstract

A class of ribonucleases termed S-RNases, which control the pistil expression of self-incompatibility, represents the only known functional products encoded by the S locus in species from the Solanaceae, Scrophulariaceae and Rosaceae. Previously, we identified a pollen-specific F-box gene, AhSLF (S locus F-box)-S2, very similar to S2-RNase in Antirrhinum, a member of the Scrophulariaceae. In addition, AhSLF-S2 also detected the presence of its homologous DNA fragments. To identify these fragments, we constructed two genomic DNA libraries from Antirrhinum self-incompatible lines carrying alleles S1S5 and S2S4, respectively, using a transformation-competent artificial chromosome (TAC) vector. With AhSLF-S2-specific primers, TAC clones containing both AhSLF-S2 and its homologs were subsequently identified (S2TAC, S5TACa, S4TAC, and S1TACa). DNA blot hybridization, sequencing and segregation analyses revealed that they are organized as single allelic copies (AhSLF-S2, -S1, -S4 and -S5) tightly linked to the S-RNases. Furthermore, clusters of F-box genes similar to AhSLF-S2 were identified. In total, three F-box genes (AhSLF-S2, -S2A and -S2C) in S2TAC (51 kb), three (AhSLF-S4, -S4A and -S4D) in S4TAC (75 kb), two (AhSLF-S5 and -S5A) in S5TACa (55 kb), and two (AhSLF-S1 and -S1E) in S1TACa (71 kb), respectively, were identified. Paralogous copies of these genes show 38–54% identity, with allelic copies sharing 90% amino acid identity. Among these genes, three (AhSLF-S2C, -S4D and -S1E) were specifically expressed in pollen, similar to AhSLF-S2, implying that they likely play important roles in pollen, whereas three AhSLF-SA alleles showed no detectable expression. In addition, several types of retroelements and transposons were identified in the sequenced regions, revealing some detailed information on the structural diversity of the S locus region. Taken together, these results indicate that both single allelic and tandemly duplicated genes are associated with the S locus in Antirrhinum. The implications of these findings in evolution and possible roles of allelic AhSLF-S genes in the self-incompatible reaction are discussed in species like Antirrhinum.

Keywords

Self-incompatibilityEvolutionS locusAntirrhinumF-box

Copyright information

© Springer-Verlag 2003

Authors and Affiliations

  • Junli Zhou
    • 1
  • Fei Wang
    • 1
  • Wenshi Ma
    • 1
    • 3
  • Yansheng Zhang
    • 1
  • Bin Han
    • 2
  • Yongbiao Xue
    • 1
  1. 1.Institute of Genetics and Developmental BiologyChinese Academy of SciencesBeijing China
  2. 2.National Center for Gene Research, Shanghai Institutes for Biological SciencesChinese Academy of SciencesShanghai China
  3. 3.School of Life SciencesHebei Normal UniversityShijiazhuangChina