Expression analyses of flower developmental genes in Eschscholzia californica

The combination and precise control of different organ identity programs underlies the flower development in angiosperms.Despite the enormous diversity in colour,shape and morphology,angiosperms share common flower architecture. Generally, any change in the gene expression is a first hint for a gain or a loss of function.The examination of gene expression and the comparison of expression patterns between lineages is a starting point to get insight into the evolution of gene function.Studying the gene expression and function in phylogenetically important species such as Eschscholzia californica (E. californica),a representative of the earliest diverging basal eudicot lineage Ranunculales and an emerging model species for investigating flower development, contributes to our understanding about the evolution of flower genetic networks underlying the evolution of the flower organ development.In this work, the orthologous gene expression patterns of key regulators in flower development of A.thaliana were examined in E. californica and compared to the expression patthers in other species. This work demonstrates that orthologous gene expression of developmental control genes is often highly conserved across angiosperm lineages, however also shifts in expression between orthologs arise by alteration in cis-regulatory elements that allow the gene function to evolve

Floral homeotic C function genes repress specific B function genes in the carpel whorl of the basal eudicot California poppy (Eschscholzia californica)

<p>Abstract</p> <p>Background</p> <p>The floral homeotic C function gene <it>AGAMOUS </it>(<it>AG</it>) confers stamen and carpel identity and is involved in the regulation of floral meristem termination in <it>Arabidopsis</it>. <it>Arabidopsis ag </it>mutants show complete homeotic conversions of stamens into petals and carpels into sepals as well as indeterminacy of the floral meristem. Gene function analysis in model core eudicots and the monocots rice and maize suggest a conserved function for <it>AG </it>homologs in angiosperms. At the same time gene phylogenies reveal a complex history of gene duplications and repeated subfunctionalization of paralogs.</p> <p>Results</p> <p><it>EScaAG1 </it>and <it>EScaAG2</it>, duplicate <it>AG </it>homologs in the basal eudicot <it>Eschscholzia californica </it>show a high degree of similarity in sequence and expression, although <it>EScaAG2 </it>expression is lower than <it>EScaAG1 </it>expression. Functional studies employing virus-induced gene silencing (VIGS) demonstrate that knock down of <it>EScaAG1 </it>and <it>2 </it>function leads to homeotic conversion of stamens into petaloid structures and defects in floral meristem termination. However, carpels are transformed into petaloid organs rather than sepaloid structures. We also show that a reduction of <it>EScaAG1 </it>and <it>EScaAG2 </it>expression leads to significantly increased expression of a subset of floral homeotic B genes.</p> <p>Conclusions</p> <p>This work presents expression and functional analysis of the two basal eudicot <it>AG </it>homologs. The reduction of <it>EScaAG1 </it>and <it>2 </it>functions results in the change of stamen to petal identity and a transformation of the central whorl organ identity from carpel into petal identity. Petal identity requires the presence of the floral homeotic B function and our results show that the expression of a subset of B function genes extends into the central whorl when the C function is reduced. We propose a model for the evolution of B function regulation by C function suggesting that the mode of B function gene regulation found in <it>Eschscholzia </it>is ancestral and the C-independent regulation as found in <it>Arabidopsis </it>is evolutionarily derived.</p

Floral homeotic C function genes repress specific B function genes in the carpel whorl of the basal eudicot California poppy (Eschscholzia californica)

<p>Abstract</p> <p>Background</p> <p>The floral homeotic C function gene <it>AGAMOUS </it>(<it>AG</it>) confers stamen and carpel identity and is involved in the regulation of floral meristem termination in <it>Arabidopsis</it>. <it>Arabidopsis ag </it>mutants show complete homeotic conversions of stamens into petals and carpels into sepals as well as indeterminacy of the floral meristem. Gene function analysis in model core eudicots and the monocots rice and maize suggest a conserved function for <it>AG </it>homologs in angiosperms. At the same time gene phylogenies reveal a complex history of gene duplications and repeated subfunctionalization of paralogs.</p> <p>Results</p> <p><it>EScaAG1 </it>and <it>EScaAG2</it>, duplicate <it>AG </it>homologs in the basal eudicot <it>Eschscholzia californica </it>show a high degree of similarity in sequence and expression, although <it>EScaAG2 </it>expression is lower than <it>EScaAG1 </it>expression. Functional studies employing virus-induced gene silencing (VIGS) demonstrate that knock down of <it>EScaAG1 </it>and <it>2 </it>function leads to homeotic conversion of stamens into petaloid structures and defects in floral meristem termination. However, carpels are transformed into petaloid organs rather than sepaloid structures. We also show that a reduction of <it>EScaAG1 </it>and <it>EScaAG2 </it>expression leads to significantly increased expression of a subset of floral homeotic B genes.</p> <p>Conclusions</p> <p>This work presents expression and functional analysis of the two basal eudicot <it>AG </it>homologs. The reduction of <it>EScaAG1 </it>and <it>2 </it>functions results in the change of stamen to petal identity and a transformation of the central whorl organ identity from carpel into petal identity. Petal identity requires the presence of the floral homeotic B function and our results show that the expression of a subset of B function genes extends into the central whorl when the C function is reduced. We propose a model for the evolution of B function regulation by C function suggesting that the mode of B function gene regulation found in <it>Eschscholzia </it>is ancestral and the C-independent regulation as found in <it>Arabidopsis </it>is evolutionarily derived.</p

Expressionsanalyse von Entwicklungsgenen in Eschscholzia californica

The combination and precise control of different organ identity programs underlies the flower development in angiosperms.Despite the enormous diversity in colour,shape and morphology,angiosperms share common flower architecture. Generally, any change in the gene expression is a first hint for a gain or a loss of function.The examination of gene expression and the comparison of expression patterns between lineages is a starting point to get insight into the evolution of gene function.Studying the gene expression and function in phylogenetically important species such as Eschscholzia californica (E. californica),a representative of the earliest diverging basal eudicot lineage Ranunculales and an emerging model species for investigating flower development, contributes to our understanding about the evolution of flower genetic networks underlying the evolution of the flower organ development.In this work, the orthologous gene expression patterns of key regulators in flower development of A.thaliana were examined in E. californica and compared to the expression patthers in other species. This work demonstrates that orthologous gene expression of developmental control genes is often highly conserved across angiosperm lineages, however also shifts in expression between orthologs arise by alteration in cis-regulatory elements that allow the gene function to evolve