Projects
Project: PTDC/AGR-GPL/70215/2006
Títle: Genetic instability in ornamental plants
The aim of the project is to uncover mechanisms underlying phenotypic variation in cultivated ornamental plants. Specifically, the proposal involves an investigation of the genetic and molecular basis of flower colour variegation in commercial varieties of Linaria and Zinnia, by applying knowledge derived from the analysis of similar phenotypes in laboratory strains of Antirrhinum. Flower colour variegation in Antirrhinum, a close relative of Linaria, is conferred by unstable mutant alleles of pigmentation genes that carry transposon insertions. Typically, insertion of a transposon in a pigmentation gene can block gene expression giving a mutant phenotype (e.g., colourless rather than the wild type red petals). However, in plants with variegated flowers, the transposon can excise somatically to generate clonal patches of pigmented cells on the colourless background (the type of variegation referred to here) or excise in germinal tissue to give some progeny with fully coloured flowers (reversion).
Preparatory research in the proponent’s laboratory led to the identification of a pigmentation gene, the expression of which is specifically impaired in the varieties of Linaria and Zinnia with variegated flower colour. This gene is therefore a candidate for transposon-trapping and for uncovering the molecular basis of variegation. Thus, the proposed research will include: (i) analysing the genetic behaviour of plants with variegated flowers. In particular, it will be determined whether these plants show germinal instability. (ii) Searching for transposon insertions in the candidate gene. (iii) Determining whether phenotypic reversion, either somatic or germinal, is attributable to transposon excision. This should provide conclusive evidence on whether transposon activity at the candidate gene is responsible for mutant phenotypes.
Preparatory research in the proponent’s laboratory led to the identification of a pigmentation gene, the expression of which is specifically impaired in the varieties of Linaria and Zinnia with variegated flower colour. This gene is therefore a candidate for transposon-trapping and for uncovering the molecular basis of variegation. Thus, the proposed research will include: (i) analysing the genetic behaviour of plants with variegated flowers. In particular, it will be determined whether these plants show germinal instability. (ii) Searching for transposon insertions in the candidate gene. (iii) Determining whether phenotypic reversion, either somatic or germinal, is attributable to transposon excision. This should provide conclusive evidence on whether transposon activity at the candidate gene is responsible for mutant phenotypes.
