Biology subjects

Escamez, S.

Publications and source records attributed to Escamez, S..

5 recordsLinked to original sources

bioRxiv2021

Fluorescence lifetime imaging as an in situ and label-free readout for the chemical composition of lignin

Important structures and functions within living organisms rely on naturally fluorescent polymeric molecules such as collagen, keratin, elastin, resilin, or lignin. Theoretical physics predict that fluorescence lifetime of these polymers is related to their chemical composition. We verified this prediction for lignin, a major structural element in plant cell walls and one of the most abundant components of wood. Lignin is composed of different types of phenylpropanoid units, and its composition affects its properties, biological functions, and the utilization of wood biomass. We carried out fluorescence lifetime imaging microscopy (FLIM) measurements of wood cell wall lignin in a population of 90 hybrid aspen trees genetically engineered to display differences in cell wall chemistry and structure. We also measured wood cell wall composition by classical analytical methods in the wood cell walls of these trees. Using statistical modelling and machine learning algorithms, we identified parameters of fluorescence lifetime that predict the content of S-type and G-type lignin units, the two main types of units in the lignin of angiosperm plants. Finally, we show how quantitative measurements of lignin chemical composition by FLIM can reveal the dynamics of lignin biosynthesis in two different biological contexts, including in vivo while lignin is being synthesized in the walls of living cells.

plant biology↗

bioRxiv2021

Identification of genetic markers and wood properties that predict wood biorefinery potential in aspen bioenergy feedstock (Populus tremula).

BackgroundWood represents the majority of the biomass on land and constitutes a renewable source of biofuels and other bioproducts. However, wood is recalcitrant to bioconversion, raising a need for feedstock improvement in production of, for instance, biofuels. We investigated the properties of wood that affect bioconversion, as well as the underlying genetics, to help identify superior tree feedstocks for biorefining. ResultsWe recorded 65 wood-related and growth traits in a population of 113 natural aspen genotypes from Sweden. These traits included three growth and field performance traits, 20 traits for wood chemical composition, 17 traits for wood anatomy and structure, and 25 wood saccharification traits as indicators of bioconversion potential. Glucose release after saccharification with acidic pretreatment correlated positively with tree stem height and diameter and the carbohydrate content of the wood, and negatively with the content of lignin and the hemicellulose sugar units. Most of these traits displayed extensive natural variation within the aspen population and high broad-sense heritability, supporting their potential in genetic improvement of feedstocks towards improved bioconversion. Finally, a genome wide association study (GWAS) revealed 13 genetic loci for saccharification yield (on a whole tree biomass basis), with six of them intersecting with associations for either height or stem diameter of the trees. ConclusionsThe simple growth traits of stem height and diameter were identified as good predictors of wood saccharification yield in aspen trees. GWAS elucidated the underlying genetics, revealing putative genetic markers for bioconversion of bioenergy tree feedstocks.

plant biology↗

bioRxiv2019

Cytokinin induction by the Jasmonate-induced AP2/ERF115 represses adventitious rooting in Arabidopsis

Jasmonate (JA), an oxylipin-derived phytohormone, plays crucial roles not only in plant immunity and defense against herbivorous insects but also in plant growth and developmental processes, including regeneration and organogenesis. However, the mechanistic basis of its mode of action and precise role in integrating other signaling cues are poorly understood. Here we provide genetic evidences that JA signaling acts in both NINJA-dependent and -independent modulation of the transcriptional activity of MYC transcription factors involved in the inhibition of adventitious root initiation (ARI). Our data show that NINJA-dependent JA signaling in pericycle cells blocks early events of ARI. Moreover, transcriptomic comparison of ninja-1myc2-322B double mutant (which produce extremely few ARs) and wild type seedlings identified a novel molecular network governed by the APETALA2/ETHYLENE RESPONSE FACTOR 115 (ERF115) transcription factor. We demonstrate that JA-induced ERF115 activates the cytokinin signaling machinery and thereby represses ARI. Altogether, our results reveal a molecular network involving cooperative crosstalk between JA and CK machineries that inhibits ARI.

plant biology↗

bioRxiv2018

Cell death in cells overlying lateral root primordia contributes to organ growth in Arabidopsis

Unlike animal development, plant organ growth is widely accepted to be determined by cell division without any contribution of cell elimination. We investigated this paradigm during Arabidopsis lateral root formation when growth of the new primordia (LRP) from pericycle-derived stem cells deep inside the root is reportedly facilitated by remodeling of the walls of overlying cells without apparent cell death. However, we observed the induction of marker genes for cell types undergoing developmental cell death in several cells overlying the growing LRP. Transmission electron microscopy, time-lapse confocal and light sheet microscopy techniques were used to establish that cell death occurred at least in a subset of endodermal LRP-overlying cells during organ emergence. Significantly, organ emergence was retarded in mutants lacking a positive cell death regulator, and restored by inducing cell death in cells overlying LRP. Hence, we conclude that in the case of LRP, cell elimination contributes to organ growth.

plant biology↗

bioRxiv2017

A Collection Of Genetically Engineered Populus Trees Reveals Wood Biomass Traits That Predict Glucose Yield From Enzymatic Hydrolysis

Wood represents a promising source of lignocellulosic biomass for the production of bio-based renewables, especially biofuels. However, woody feedstocks must be improved to become competitive against petroleum. We created a collection of Populus trees consisting of 40 genetically engineered lines to modify and to better understand wood biomass properties. A total of 65 traits were measured in these trees and in the corresponding wild-type clone, including growth parameters, wood anatomical and structural properties, cell wall composition and analytical saccharification. The relationships between saccharification of glucose and biomass traits were investigated using multivariate data analysis methods and mathematical modeling. To circumvent potential trade-offs between biomass production and saccharification potential, we also estimated the \"total-wood glucose yield\" (TWG) expected after pretreatment and 72h of enzymatic hydrolysis from whole trees. A mathematical model estimated TWG from a subset of 22 wood biomass traits with good predictivity (Q2 = 0.8), while saccharification of glucose could be predicted from seven biomass traits (Q2 = 0.49). Among the seven diagnostic traits for saccharification, four also affected biomass production, such as the ratio of S- to G-lignin which was beneficial for saccharification but detrimental for growth. The contents of various matrix polysaccharides appeared important for predicting both saccharification and TWG, including low abundance monosaccharides. In particular, fucose and mannose contents negatively correlated with TWG, apparently by negatively associating with biomass production. Both biomass production and saccharification, and hence TWG, negatively correlated with arabinose and rhamnose contents, suggesting that these low abundance monosaccharides represent markers/targets for improving feedstocks.

plant biology↗