Biology subjects

Figueras, M.

Publications and source records attributed to Figueras, M..

4 recordsLinked to original sources

bioRxiv2025

The vacuolar protein 8 (Vac8) homolog in Cryptococcus neoformans plays conserved and unique roles in vacuolar and cellular morphology, impacting important stress responses and virulence traits

Functionally similar to a plant vacuole or a mammalian lysosome, the fungal vacuole plays a vital role in many cellular processes. Most studies of the vacuole have been performed in the nonpathogenic yeast Saccharomyces cerevisiae; however, recently in pathogenic fungi, the vacuole has been implicated in host invasion in both plants and mammals highlighting an important role for the vacuole in pathogenesis. Here, we report that deletion of Cryptococcus neoformans vacuolar protein 8 (VAC8) results in a fragmented vacuole morphology, impairment of vacuolar fusion, and inability to form titan cells. Additionally, absence of Vac8 results in defective growth at high temperature and in the presence of caffeine, suggesting a defect in cell wall signaling. Interestingly, despite aberrant vacuole morphology, vac8{Delta} is slightly more resistant to fluconazole treatment, and displays increased resistance to hydrogen peroxide, suggesting the irregular vacuole morphology does not impair vacuole function. Like S. cerevisiae Vac8, C. neoformans Vac8 is comprised of armadillo repeat regions which form alpha helices that fold to form a superhelix allowing for increased protein-protein interaction. Many of the known binding partners of S. cerevisiae Vac8 are not present in the C. neoformans genome, suggesting novel functions for Vac8 in this fungus. Notably, deletion of VAC8 affected some virulence traits, providing support to targeting the fungal vacuole as a potential therapeutic intervention.

microbiology↗

bioRxiv2023

A Functional Exodermal Suberin is Key for Plant Nutrition and Growth in Potato

Angiosperm roots, except in Arabidopsis, have both endodermis and exodermis, which regulate radial water and solute movement through lignin and suberin deposition. While endodermal suberin in Arabidopsis acts as a barrier to water and solute uptake and backflow, its implications in other angiosperms with both layers and the role of exodermal suberin remain unclear. We examined potato roots (Solanum tuberosum) and found that exodermis lacks the typical Casparian strip but forms an outer lignin cap, and quickly suberizes near the root tip. In contrast, a few endodermal cells, with Casparian strip, start suberizing much later. The continuous early exodermal suberization covering the root underlines its potential role in mineral nutrient radial movement. To demonstrate it, we used plants downregulating the suberin biosynthetic gene CYP86A33, which had the root suberin reduced in a 61%. Phenotypic analyses of the suberin-deficient mutant showed altered mineral nutrient concentration, slightly reduced water content and compromised growth. Micro-PIXE analyses identified the distribution of elements within the roots and highlighted anatomical compartments defined by apoplastic barriers. These findings advance our understanding of nutrient radial transport, demonstrate exodermal suberin as a bidirectional and selective barrier to element movement, and underscore its importance in nutrient homeostasis and plant growth.

plant biology↗

bioRxiv2023

Rhytidome- and cork-type barks of holm oak, cork oak and their hybrids highlight processes leading to cork formation

The periderm is basic for land plants due to its protective role during radial growth, which is achieved by the polymers deposited in the cell walls. In most trees, like holm oak, the periderm is frequently replaced by subsequent internal periderms yielding a heterogeneous outer bark made of a mixture of periderms and phloem tissues, known as rhytidome. Exceptionally, cork oak forms a persistent or long-lived periderm which results in a homogeneous outer bark of thick phellem cell layers known as cork. Here we use the outer bark of cork oak, holm oak, and their natural hybrids to analyse the chemical composition, the anatomy and the transcriptome, and further understand the mechanisms underlying periderm development. The inclusion of hybrid samples showing rhytidome-type and cork-type barks is valuable to approach to cork and rhytidome development, allowing an accurate identification of candidate genes and processes. The present study underscores that biotic stress and cell death signalling are enhanced in rhytidome-type barks whereas lipid metabolism and cell cycle are enriched in cork-type barks. Development-related DEGs, showing the highest expression, highlight cell division, cell expansion, and cell differentiation as key processes leading to cork or rhytidome-type barks.

cell biology↗

bioRxiv2021

Induced ligno-suberin vascular coating and tyramine-derived hydroxycinnamic acid amides restrict Ralstonia solanacearum colonization in resistant tomato roots

The soil borne pathogen Ralstonia solanacearum is the causing agent of bacterial wilt, a devastating disease affecting major agricultural crops. R. solanacearum enters plants through the roots and reaches the vasculature, causing rapid wilting. We recently showed that tomato varieties resistant to bacterial wilt restrict bacterial movement in the plant. In the present work we go a step forward by identifying the physico-chemical nature of the barriers induced in resistant tomato roots in response to R. solanacearum. We describe that resistant tomato specifically responds to infection by assembling de novo a structural barrier at the vasculature formed by a ligno-suberin coating and tyramine-derived hydroxycinnamic acid amides (HCAAs). On the contrary, susceptible tomato does not form these reinforcements in response to the pathogen but instead displays lignin structural changes compatible with its degradation. Further, we show that overexpressing genes of the ligno-suberin pathway in a commercial susceptible variety of tomato restricts R. solanacearum movement inside the plant and slows disease progression, enhancing resistance to the pathogen. We thus propose that the induced barrier in resistant plants does not only restrict the movement of the pathogen, but may also prevent cell wall degradation by the pathogen and confer anti-microbial properties.

plant biology↗