Characterization of the genes determining pollen specificity in self-incompatibility mechanism of Malus x domestica

• Autor(a) principal: Nunes, Vanessa Catarina Ribeiro
• Data de Publicação: 2015
• Tipo de documento: Dissertação
• Idioma: eng
• Título da fonte: Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)
• Texto Completo: http://hdl.handle.net/10773/15402
• topic: Biologia molecular e celular; Reprodução vegetal; Angiospérmicas; Genética vegetal

To understand the molecular basis of the S-RNase-based gametophytic selfincompability system of subtribe Pyrinae from Rosaceae family, in this work, Malus x domestica species was used to determine the genes involved in pollen S-specificity. Previously 18 F-box genes, similar to the S-locus F-box brothers (SFBBs), were identified by conventional polymerase chain reaction techniques and with the pollen transcriptome analysis of nine M. domestica cultivars. However, not all 10 S-haplotypes, covered by the nine M. domestica cultivars used, have been characterized for all SFBB genes, and 12 SFBB sequences found, align as highly divergent sequences in 12 SFBB genes. Thus, in this work, by cloning and sequencing analysis of two highly diverged alleles, namely, SFBBGu8 and SFBBN3 of SFBB5 and SFBB1 genes, respectively, was concluded that SFBBGu8 sequence represent the S1- and S24- diverged alleles of SFBB5 gene, while SFBBN3 sequence represent the S28- diverged allele of SFBB1 gene. Additionally, for SFBB5 gene there is no SFBB copy number variation. This pattern was also observed for other 12 SFBB genes. For 15 of the 18 SFBB genes identified, linkage with the S-RNase gene (gene involved in pistil S-specificity) was established by segregation analysis of the F1 progeny from the cross of Fuji (S1, S9) with Honeycrisp (S2, S24), previously genotyped. As result, for SFBB2, SFBB3, SFBB4, SFBB6, SFBB7, SFBB8, SFBB9, SFBB10, SFBB11, SFBB12, SFBB13, SFBB14 and SFBB16 genes, linkage with at least one S-RNase allele was established. Thus, since these 13 SFBB genes also present pollen-specific expression and S-haplotypespecific polymorphism, these genes are pollen S-genes. In conclusion, consistent features with the collaborative non-self recognition model, were identified in M. domestica species, such as, large number of SFBB genes and the presence of highly diverged SFBB alleles, that may be conserved in other S-haplotypes, and thus, involved in the recognition of a particular non-self S-RNase. However, in M. domestica species, it was not verified SFBB copy number variation within the different S-haplotypes, as observed in Petunia. The characterization of the S-pollen genes involved in the self-incompatibility mechanism in M. domestica species is the first step to characterize self-pollen rejection mechanism in Pyrinae subtribe.