The suberinteresting role of GELP proteins

Trabajo presentado a la XVI Reunión de Biología Molecular de Plantas-Meeting of Plant Molecular Biology (RBMP) celebrada en Sevilla entre el 14 y el 16 de diciembre de 2022.Plants roots take up essential nutrients and block out unwanted compounds from the soil by using a selective barrier in the roots known as the endodermis. Endodermis contains ring-shaped and lignin-based Casparian strip network that acts as a difusion barrier (Barbosa et al., 2019). Later in development, endodermal cells suberize to produce ‘patchy’ suberization that eventually leads to a zone of continuous suberin deposition (Serra and Geldner 2022). The two impermeable polymers, lignin and suberin, afect paracellular and transcellular transport, respectively. Suberin is a lipophilic polyester composed of fatty acids, glycerol and some aromatics. It’s deposited as a hydrophobic layer between the primary cell wall and plasma membrane. Despite suberin being a major plant polymer, fundamental aspects of its biosynthesis and plasticity have remained unclear. Plants shape their root system via lateral root formation, an auxin-induced process requiring local degradation and re-sealing of endodermal suberin. We demonstrated that diferentiated endodermis has a specifc, auxin-mediated transcriptional response, dominated by cell wall remodelling genes. We identifed two sets of auxin-regulated GELP proteins (GDSL-lipases). Using an optimized CRISPR-Cas9 gene editing toolset (Ursache et al., 2021), we discovered that one set of GELPs is required for suberin polymerization, while the other can drive suberin degradation (Ursache et al., 2021). These enzymes constitute novel core players of suberisation, driving root suberin plasticity during plant growth and in response to the environmental stress.EMBO long term fellowship (EMBO ALTF 1046-2015), University of Lausanne (UNIL) and Centre for Research in Agricultural Genomics (CRAG)

Contemporary Vietnam: Political Opportunities, Conservative Formal Politics, and Patterns of Radical Change

This article examines contemporary Vietnamese politics and argues that many opportunities remain for political rethinking. It examines linguistic arguments that point to a perpetuation of traditional Communist ideas in two crucial areas—village elections and the treatment of “policy.” It then juxtaposes this formal conservatism with two areas of tension. First, problems exist in addressing important policy questions related to rural development, poverty, and participation. These suggest that without major rethinking of fundamental political issues, such problems are increasingly hard to address. Second, it examines the context of formal politics, looking at evidence for successful contestation over leadership positions in villages and the rise of informal farmers’ groups. Both have often led local officials to simple toleration and accommodation rather than exploitation of such trends to assist their own repositioning in ways that could gain them popular political support.Again, such trends highlight the void in formal political rethinking. Both of these areas of tension create considerable difficulties for donors and external partners, whose approaches are often premised upon both a familiar policy-driven role for the state in development and ignorance of local political processes

Elicitor-dependent activation of defence-related promoters in the TZ and DZ of the root.

<p>(a) Quantification of microscopic analysis of <i>Promoter</i>::<i>YFP</i>_<i>N</i> constructs in the differentiation zone of 7-days old seedlings following treatment with 100 nM flg22, chi7, AtPep1 or 0.5x MS as control. Images were analysed using Fiji. Bars represent the mean of ≥ 3 images ± SD. (b) Overview of inductive and suppressive responses of <i>Promoter</i>::<i>YFP</i>_<i>N</i> constructs in different developmental root zones analysed as described under (a). Numbers in the upper row indicate the sum of significant marker responses in one of the four analysed root zones for a given elicitor, while numbers in the lower row indicate the total sum of significant responses from all markers and all root zones for a given elicitor. Black colour indicates induction, white colour suppression and grey colour non-significant changes.</p

Verification of elicitor-triggered responses of <i>promoter</i>::<i>YFP</i>_<i>N</i> markers by qPCR.

<p>(a) Signal quantification using micrographs from roots expressing <i>pMYB51</i>::<i>YFP</i>_<i>N</i> and <i>pACS6</i>::<i>YFP</i>_<i>N</i>. 7-day old seedlings were treated with 100 nM flg22, chi7 or AtPep1 or 0.5x MS without elicitor and analysed in four developmental zones. Bars represent the sum of average signals obtained for each of the four developmental zones from 2–3 independent transformation lines per construct. (b) Expression of <i>pMYB51</i>::<i>YFP</i>_<i>N</i> and <i>pACS6</i>::<i>YFP</i>_<i>N</i> in the differentiation zone of 7-day old seedlings treated with 100 nM flg22, chi7 or AtPep1 or 0.5x MS without elicitor. Bar 100 μm. (c) Expression of <i>MYB51</i> and <i>ACS6</i> analysed by quantitative RT-PCR following 2 h treatment of 7-day old seedlings with 100 nM flg22, chi7 or AtPep1 or 0.5x MS without elicitor. Transcript levels were normalized to the reference gene <i>UBIQUITIN5</i> before calculation of expression relative to the control. The experiment was repeated three times with similar results.</p

Responses of PAMP-triggered immunity in roots.

<p>(a) Luminol-based detection of ROS production in isolated roots of Col-0 seedlings treated with 1 μM flg22, chi7 or AtPep1 or without elicitor. Data represent the mean of 12 replicates ± SE. RLU—relative luminescence units (b) Activation of MAP kinases detected by western blot (MPK). Isolated roots from 2-week old seedlings of Col-0 and transgenic lines were treated with 1 μM flg22, chi7 or AtPep1 or without elicitor for 10 min before sampling. Ponceau S staining was used as loading control (PS). The experiment was performed three times with similar results.</p

Root growth inhibition by AtPep1.

<p>(a) Col-0 wild-type and transgenic lines were germinated and grown vertically for 12 days on 0.5x MS containing 10 nM, 100 nM or 1 μM flg22, chi7 or AtPep1 or without elicitor. (b) Analysis of primary root length was performed using Fiji on images recorded under (a) and is shown as box plots representing ≥ 20 roots per sample. The experiment was performed three times for Col-0 and two times for <i>pepr1 pepr2</i>. Statistical analysis was performed using a Student’s t-test comparing with roots grown on control medium: * p < 0.05, ** p < 0.01, *** p < 0.001.</p

Elicitor-triggered responses of <i>pHEL</i>::<i>YFP</i>_<i>N</i>.

<p>(a) Microscopic analysis of root developmental zones of 7-days old <i>pHEL</i>::<i>YFP</i>_<i>N</i> seedlings following 24 h treatment with 100 nM flg22, chi7, AtPep1 or 0.5x MS as control. RC—root cap / meristem, TZ—transition zone, DZ—differentiation zone, MZ—mature zone. Bar 100 μM. (b) Quantification of fluorescent signals from microscopic analysis of different developmental zones of <i>pHEL</i>::<i>YFP</i>_<i>N</i> as described under (a) using Fiji. Bars represent the mean of ≥ 3 images ± SD.</p

GDSL-domain proteins have key roles in suberin polymerization and degradation

Plant roots acquire nutrients and water while managing interactions with the soil microbiota. The root endodermis provides an extracellular diffusion barrier through a network of lignified cell walls called Casparian strips, supported by subsequent formation of suberin lamellae. Whereas lignification is thought to be irreversible, suberin lamellae display plasticity, which is crucial for root adaptative responses. Although suberin is a major plant polymer, fundamental aspects of its biosynthesis and turnover have remained obscure. Plants shape their root system via lateral root formation, an auxin-induced process requiring local breaking and re-sealing of endodermal lignin and suberin barriers. Here, we show that differentiated endodermal cells have a specific, auxin-mediated transcriptional response dominated by cell wall remodelling genes. We identified two sets of auxin-regulated GDSL lipases. One is required for suberin synthesis, while the other can drive suberin degradation. These enzymes have key roles in suberization, driving root suberin plasticity