Biology subjects

Fournier, P.

Publications and source records attributed to Fournier, P..

3 recordsLinked to original sources

bioRxiv2023

Comparative Phylogenomics and Phylotranscriptomics Provide Insights into the Genetic Complexity of Nitrogen Fixing Root Nodule Symbiosis

Plant root nodule symbiosis (RNS) with mutualistic nitrogen-fixing bacteria is restricted to a single clade of angiosperms, the Nitrogen-Fixing Nodulation Clade (NFNC), and is best understood in the legume family. It is widely accepted that nodulation originated through the assembly of modules recruited from existing functions, such as mycorrhizal symbiosis, polar growth, and lateral root development. Because nodulating species are scattered within the NFNC, the number of times nodulation has evolved or has been lost has been a matter of considerable speculation. This interesting evolutionary question has practical implications concerning the ease with which nodulation might be engineered in non-nodulating crop plants. Nodulating species share many commonalities, due either to divergence from a common ancestor over 100 million years ago or to convergence or deep homology following independent origins over that same time period. In either case, comparative analyses of diverse nodulation syndromes can provide insights into constraints on nodulation--what must be acquired or cannot be lost for a functional symbiosis--and what the latitude is for variation in the symbiosis. However, much remains to be learned about nodulation, especially outside of legumes. Here we present new information across the spectrum of nodulating groups. We find no evidence for convergence at the level of amino acid residues or gene family expansion across the NFNC. Our phylogenomic analyses further emphasize the uniqueness of the transcription factor, NIN, as a master regulator of nodulation, and identify key mutations affecting its function across the NFNC. We find that nodulation genes are over-represented among orthologous gene groups (OGs) present in the NFNC common ancestor, but that lineage-specific OGs play major roles in nodulation. We identified over 900,000 conserved noncoding elements (CNEs), of which over 300,000 were unique to NFNC species. A significant proportion of these are associated with nodulation-related genes and thus are candidates for transcriptional regulators.

evolutionary biology↗

bioRxiv2022

Neighbourhood effect of weeds on wheat root endospheric mycobiota

O_LIMicroorganisms associated with plants provide essential functions to their hosts, and therefore affect ecosystem productivity. Agricultural intensification has modified microbial diversity in the soil reservoir and may affect plant microbial recruitment. Weeds develop spontaneously in crop fields, and could influence microorganisms associated with crop plants through a neighbourhood effect. We explore the effect of weed species on crop plant microbiota as potentially auxiliary plants that affect agricultural productivity. C_LIO_LIWe combined field and controlled laboratory studies to analyse the neighbourhood effect of weeds on wheat root endospheric mycobiota and growth. First, we analysed the effect of weed species diversity and identity recorded in the neighbourhood of individual wheat plants on soil and wheat root mycobiota in the field. Second, we used a plant-matrix design in laboratory conditions to test the effect of weed identity (9 weed treatments) and their ability to transmit root mycobiota to wheat roots, and the resulting impact on wheat growth. C_LIO_LIIn contrast to soil mycobiota, we demonstrated that wheat root endospheric mycobiota was influenced by the diversity and identity of weeds developing in their 1 m2 neighbourhood. Wheat root endospheric microbiota strongly differs in terms of richness and composition depending on the neighbouring weed plant species. Weed species transmitted from 13% to 74% of their root microbiota to wheat roots depending on weed identity in controlled conditions. C_LIO_LISynthesis. Weed neighbours modified wheat plant performance, possibly as a result of competitive interactions and changes in microbiota. Our findings suggest that crop root mycobiota was variable and was modulated by their weed neighbourhood. Synergistic effects between mycobiota of crops and weeds could therefore contribute to soil biodiversity and sustainable agriculture. C_LI

ecology↗

bioRxiv2021

Early transcriptomic response of Alnus glutinosa to Frankia alni symbiont, an upregulated nsLTP (non-specific Lipid Transfer Protein) is implicated in early and late stages of symbiosis

Alnus glutinosa response to Frankia alni is driven by several sequential physiological modifications that include calcium spiking, root hair deformation, penetration, induction of primordium, formation and growth of nodule. Here, we have conducted a transcriptomic study to analyse plant responses to Frankia alni at early stages of symbiosis establishment. Forty-two genes were significantly activated by either with a Frankia culture supernatant or with living cells separated from the roots by a dialysis membrane permitted to identify plant genes which expression changes upon early contact with Frankia. Most of these genes encode biological processes, including oxidative stress and response to stimuli. The most upregulated gene is the non-specific lipid transfer protein (nsLTP) encoding gene with a fold change of 141. Physiological experiments showed that nsLTP increases Frankia nitrogen fixation at sub-lethal concentration. Immunohistochemistry experiments conducted at an early infection stage indicated that nsLTP protein is localized at the deformed root hair region after Frankia inoculation and later in nodules, precisely around bacterial vesicles. Taken together, these results suggest that nsLTP acts at early and late stages of symbiosis, probably by increasing nitrogen uptake by Frankia.

plant biology↗