Molecular and genetic characterization of novel S-RNases from a natural population of Nicotiana alata

JUAN A ROLDÁN; RODRIGO QUIROGA; ARIEL GOLDRAIJ

PLANT CELL REPORTS

SPRINGER

Año: 2010 p. 735 - 746

0721-7714

Abstract Self-incompatibility in the Solanaceae is mediated by S-RNase alleles expressed in the style, which confer specificity for pollen recognition. Nicotiana alata has been successfully used as an experimental model to elucidate cellular and molecular aspects of S-RNase based self-incompatibility in Solanaceae. However, S-RNase alleles of this species have not been surveyed from natural populations and consequently the S-haplotype diversity is poorly known. Here the molecular and functional characterization of seven S-RNase candidate sequences, identified from a natural population of Nicotiana alata, are reported. Six of these candidates, S5, S27, S70, S75, S107, and S210, showed plant-specific amplification in the natural population and style specific expression, which increased gradually during bud maturation, consistent with the reported S-RNase expression. In contrast, the S63 ribonuclease was present in all plants examined and was ubiquitously expressed in different organs and bud developmental stages. Genetic segregation analysis demonstrated that S27, S70, S75, S107, and S210 alleles were fully functional novel S-RNases, while S5 and S63 resulted to be non-S-RNases, although with a clearly distinct pattern of expression. These results reveal the importance of performing functional analysis in studies of S-RNase allelic diversity. Comparative phylogenetic analysis of six species of Solanaceae showed that Nicotiana alata S-RNases were included in eight transgeneric S-lineages. Phylogenetic pattern obtained from the inclusion of the novel S-RNase alleles confirms that Nicotiana alata represents a broad sample of the allelic variation at the S-locus of the Solanaceae.