Biology subjects

Airoldi, C. A.

Publications and source records attributed to Airoldi, C. A..

3 recordsLinked to original sources

bioRxiv2025

Replicated repurposing of an ancestral transcriptional complex in land plants

Transcriptional complexes with a common composition regulate the production of flavonoid pigments, trichomes, root hairs and other epidermal traits in seed plants. These complexes are composed of transcription factors from the MYB and basic helix-loop-helix (bHLH) families along with a tryptophan-aspartate repeat (WDR) scaffold protein (MBW complexes). The MYB member has been found to be the most pathway-specific component of the complex and modifications to these MYB genes are overrepresented in studies investigating the genetic basis of changes in pigmentation phenotypes across flowering plants. Here we investigated the orthologues of the MBW complex in a divergent lineage to understand its origin and evolution. We found evidence that these transcriptional complexes also form in the liverwort Marchantia polymorpha, indicating, together with an analysis of published gene family phylogenies, that they are ancestral to land plants. The functions of each of the two orthologous MYB genes, MpMYB14 and MpMYB02, both depend on the single orthologous bHLH gene, MpbHLH12. We could not assess the functional role of the WDR genes in M. polymorpha, due to low mutant recovery suspected to be caused by pleiotropic effects on viability. We propose that the two transcriptional complexes with alternative MYB paralogues in M. polymorpha represent an ancestral function, regulation of the flavonoid pathway, and a derived function, maturation of liverwort-specific oil bodies. Our findings imply a replicated pattern by which new complexes have evolved in independent land plant lineages, through duplication of the evolutionarily labile MYB member and co-option of its interaction partners.

plant biology↗

bioRxiv2024

HtDCR-like1 regulates the development of structurally coloured cuticle by modulating cuticle chemistry and mechanical properties in Hibiscus trionum

O_LIStructural colours are a unique trait present in some animals, plants and even bacteria. In Hibiscus trionum flowers, they arise from nano-scaled cuticular ridges and may improve pollinator foraging efficiency. These ridges result from the buckling of the cuticle which is thought to be controlled by multiple parameters including anisotropic cell growth, chemical differentiation of the cuticle and formation of two layers of different mechanical properties. C_LIO_LIHere we investigate further the molecular and physical mechanisms by which structural colours are achieved in Hibiscus trionum. We produced two transgenic lines overexpressing HtDCR-like1, encoding a BAHD acyltransferase involved in cuticle synthesis. Transgenic lines showed impairment of the production of cuticle striations. Cuticle thickness, cuticle chemistry, cell elongation and cuticle stiffness were then investigated to identify the cause of failed buckling. C_LIO_LIWe found that HtDCR-like1 overexpression leads to modification of cuticle chemistry, including a decrease in detectable C16H32O4 (10,16-DHP) and a change to the measured Youngs moduli of the cuticle layers without alteration of the cell growth pattern. C_LIO_LIThis work demonstrates the mechanisms by which gene regulation may control complex physical phenomena such as cuticle buckling via alteration of material properties of living tissues. C_LI

plant biology↗

bioRxiv2024

Characterisation of cuticle mechanical properties: analysing stiffness in layered living systems to understand surface buckling patterns

Development of a living organism is a highly regulated process during which biological materials undergo constant change. De novo material synthesis and changes in mechanical properties of materials are key for organ development; however, few studies have attempted to produce quantitative measurements of the mechanical properties of biological materials during growth. Such quantitative analysis is particularly challenging where the material is layered, as is the case for the plant cuticle on top of the plant epidermal cell wall. Here, we focus on Hibiscus trionum flower petals, where buckling of the cuticle forms ridges, producing an iridescent effect. This ridge formation is hypothesised to be due to mechanical instability, which directly depends upon the mechanical properties of the individual layers within the epidermal cells. We present measurements of the mechanical properties of the surface layers of petal epidermal cells through atomic force microscopy (AFM) and the uniaxial tensile tester for ultrathin films (TUTTUT), across growth stages. We found that the wavelength of the surface ridges was set at the ridge formation stage, and this wavelength was preserved during further petal development, most likely because of the plasticity of the material. Our findings suggest that temporal changes in biological material properties are key to understanding the development of biological surface patterns.

plant biology↗