Beatriz Gonçalves | PlantDEvo Lab

Currently

Understanding the origin and diversification of the carpel

Currently I am working on a research program on the development and evolution of the carpel.

The carpel is the female reproductive organ of flowering plants. It encloses the ovules, protecting them, and facilitating their fertilization. After fertilization, the ovules give rise to the seeds and the carpel produces the fruit. By protecting the seed and helping disperse it, the innovative structure of the carpel played a key role in the diversification of flowering plants which account for nearly 90% of all plant species. Nearly all plant-based foods are either derived from a flowering plant or are a direct product of the carpel. Despite its importance, explaining the origin of the flowering plant carpel remains one of the enduring challenges for plant scientists.

Understanding how the closed carpel evolved from the open structures of ancestral seed plants and how its closed structure is made is key to explaining both the success of flowering plants and the origin of fruit shape diversity.

I am working on a multidisciplinary research program to tackle the evolution of the carpel from a developmental perspective. I want to explain how the closed structure of the carpel is made, how it evolved from an open leaf-like structure, and how the ancestral carpel evolved into the different carpel shapes seen across flowering plants. To understand how the carpel shape is made I will investigate how genes influence plant tissue growth during organ formation. To discover how different shapes are generated through evolution I will examine how the patterns and roles of those genes are modified in species with different carpel shapes. To master these processes at a mechanistic level, I will combine classic molecular and genetic characterization of targeted candidate genes with computational modelling techniques.

This approach is based on my recent work on the origin of the cup-shaped trap of some carnivorous plants - you can read about that below.

Past Research

Clockwise from top left: schematics of Utricularia gibba anatomy showing thick stolon and leaflet with trap; Utricularia trap (approx. 1 mm diameter); microscopy image of trap in section showing the two cell-layer structure and hollow interior; RNA in situ hybridisation showing PHV1 gene expression on the inside layer of the trap.

The development and evolution of complex leaf shapes

Postdoctoral Research Fellow at John Innes Centre

In Enrico Coen’s lab I have been studying the molecular and tissue growth patterns that underlie the 3D development of traps in the carnivorous plant Utricularia gibba. U. gibba is an aquatic species that produces two extremes of leaf shape, filiform radial leaflets and the highly complex cup-shaped traps. Integrating classic molecular and genetic tools with computational modelling methods, we have shown how simple shifts in the gene expression patterns that define the adaxial and abaxial sides of a plant organ can lead to dramatic shape transitions between flat, filiform and cup-shaped organs.

Diverse developmental roles of CUC transcription factors in Arabidopsis and beyond

Postdoctoral Researcher at Institut Jean Pierre Bourgin

In the team Transcription Factors and Architecture I worked with Nicolas Arnaud and Patrick Laufs to explore the roles of CUC genes in ovule and leaf development.

Using fluorescent reporters I showed that while CUC1 and CUC2 are broadly expressed in the placenta, CUC3 is expressed in a discrete pattern between the presumptive ovule primordia. This domain slightly overlaps with the domain of CUC2 and we were also able to show that CUC2 and CUC3 can interact. Using a series of mutant lines we showed that lack of CUC expression leads to strong ovule fusion defects and production of aberrant fused seeds.

During this postdoc I also participated in a genetic screen to identify members of the CUC gene network in leaf morphogenesis. I identified a mutant that restores serration levels to nearly wild-type in a highly serrated line that overexpresses CUC2. Using a combination of molecular and genetic approaches I determined that a mutation in the gene MURUS1 (MUR1) which encodes an enzyme required for the production of GDP-L-fucose is responsible for the reduction of serrations in this line. Using fluorescent reporter lines we showed that both the promoter activity and protein levels of CUC2 are reduced in the mur1 mutant. Finally, morphometric analysis of leaf dissection using MorphoLeaf showed that fucose is specifically required for sustained differential growth at the leaf margin during serration formation.

More about the team's research here.

Top: Nigella damascena flower variants with petals (left) and without (right).

Bottom (left to right): RNA in situ hybridisation on a flower bud showing expression of AP3 gene in petals; individual petal, sepals and sepal-like organs; micrograph images of cells on the surface of petals and sepals.

Genetic origin and ecological impact of floral variations in Nigella (Love-in-a-mist)

PhD Thesis at UMR Génétique Quantitative et Évolution Le Moulon

During my PhD thesis under the supervision of Catherine Damerval and Domenica Manicacci I studied the molecular and developmental basis of a floral dimorphism in the basal eudicot species Nigella damascena. This dimorphism is based on the presence/absence of petals, an increase in the number of perianth organs (sepal or sepal-like) and the presence of mixed identity organs with sepal and anther traits in the apetalous form. I combined a candidate gene approach with in situ hybridisation, SEM and VIGS to reveal that the full range of defects in the apetalous form is caused by the insertion of a transposable element in a homolog of the floral organ identity gene APETALA3 (AP3).

More about the team's research here (in french).

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