Structural and transcriptional analysis of S-locus F-box genes in Antirrhinum |
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| Authors: | Junli?Zhou,Fei?Wang,Wenshi?Ma,Yansheng?Zhang,Bin?Han,Yongbiao?Xue mailto:ybxue@genetics.ac.cn" title=" ybxue@genetics.ac.cn" itemprop=" email" data-track=" click" data-track-action=" Email author" data-track-label=" " >Email author |
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| Affiliation: | (1) Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, 100080 Beijing , China;(2) National Center for Gene Research, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, 500 Caobao Road, 200233 Shanghai , China;(3) Present address: School of Life Sciences, Hebei Normal University, 050016 Shijiazhuang, Hebei Province, China |
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| 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.Sequence data from this article have been deposited with the EMBL/GenBank databases under accession numbers AJ300474, AJ515534, AJ515536 and AJ515535 |
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| Keywords: | Self-incompatibility Evolution S locus Antirrhinum F-box |
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