Biology subjects

Faoro, F.

Publications and source records attributed to Faoro, F..

4 recordsLinked to original sources

bioRxiv2025

The proximal proteome of FLOWERING LOCUS T LIKE 1 during rice panicle development suggests cell-to-cell mobility features

Flowering is promoted by perception of favorable environmental stimuli. In rice, exposure of leaves to short days induces the differentiation of a branched inflorescence called panicle at the shoot apical meristem (SAM). Systemic communication from the leaves to the SAM is mediated by members of the phosphatidylethanolamine-binding protein (PEBP) family, including HEADING DATE 3a (Hd3a) and RICE FLOWERING LOCUS T 1 (RFT1), commonly referred to as florigens. Florigens are [~]20kDa proteins translated in leaf companion cells and loaded into the phloematic stream, through which they reach the SAM. Once in meristematic cells, they are translocated to the nucleus, where they form higher-order protein complexes that include transcription factors and drive transcriptional reprogramming of meristematic cells. The activity of Hd3a and RFT1 at the SAM is partly mediated by FLOWERING LOCUS T LIKE 1 (FTL1) encoding a florigen-like protein required to accelerate flowering and establish the branching pattern of the panicle. The photoperiodic regulatory network is largely based on protein-protein interactions (PPIs), that take place in different tissues and in response to environmental variation. Capturing the full extent of these interactions for a specific protein and in vivo is a challenging task. Here, we developed a protocol of Proximity Labeling (PL) to study the interactome of FTL1 in developing panicles. We show that FTL1 associates with, or is proximal to, several proteins implicated in vesicular trafficking, microtubule binding and transcriptional regulation. Using a transient system, we demonstrate that FTL1 can actively move between cells, similarly to Hd3a and RFT1. This study establishes a protocol to implement PL for the study of a dynamic process during rice reproductive development, identifies interactors of FTL1, and suggests novel features possibly linked to its function.

developmental biology↗

bioRxiv2024

From insect endosymbiont to phloem colonizer: comparative genomics unveils the lifestyle transition of phytopathogenic Arsenophonus strains

Bacteria infecting the plant phloem represent a growing threat worldwide. While these organisms often resist in vitro culture, they multiply both in plant sieve elements and hemipteran vectors. Such cross-kingdom parasitic lifestyle has emerged in diverse taxa via distinct ecological routes. In the genus Arsenophonus, the phloem pathogens Candidatus Arsenophonus phytopathogenicus (Ap) and Ca. Phlomobacter fragariae (Pf) have evolved from insect endosymbionts, but the genetic mechanisms underlying this transition have not been explored. To fill this gap, we obtained the genomes of both strains from insect host metagenomes. The resulting assemblies are highly similar in size and functional repertoire, rich in viral sequences, and closely resemble the genomes of several facultative endosymbiotic Arsenophonus strains of sap-sucking hemipterans. However, a phylogenomic analysis demonstrated distinct origins, as Ap belongs to the "Triatominarum" clade whereas Pf represents a distant species. We identified a set of orthologs encoded only by Ap and Pf in the genus, including hydrolytic enzymes likely targeting plant substrates. In particular, both bacteria encode plant cell-wall degrading enzymes and cysteine peptidases related to xylellain, a papain-like peptidase from Xylella fastidiosa, for which close homologs are found in diverse proteobacteria infecting the plant vasculature. In silico predictions and expression analyses further support a role during phloem colonization for several of the shared orthologs. We conclude that the double emergence of phytopathogenicity in Arsenophonus may have been mediated by a few horizontal gene transfer events, involving genes first acquired from other proteobacteria including phytopathogens. ImportanceWe investigate the genetic mechanisms of a transition in bacterial lifestyle. We focus on two phloem pathogens belonging to the genus Arsenophonus: Ca. Arsenophonus phytopathogenicus and Ca. Phlomobacter fragariae. Both bacteria cause economically significant pathologies, and they have likely emerged among facultative insect endosymbionts. Our genomic analyses show that both strains are highly similar to other strains of the genus associated with sap-sucking hemipterans, indicative of a recent lifestyle shift. Importantly, although the phytopathogenic Arsenophonus strains belong to distant clades, they share a small set of orthologs unique in the genus pangenome. We provide evidence that several of these genes produce hydrolytic enzymes that are secreted and target plant substrates. The acquisition and exchange of these genes may thus have played a pivotal role in the lifestyle transition of the phytopathogenic Arsenophonus strains..

microbiology↗

bioRxiv2021

Plant secondary metabolite diversity reflects both phylogeny and ecological adaptation

A phylogenetic framework explaining plant secondary metabolite diversity is lacking, but metabolite classes could represent adaptations to habitat resource availability. We test the hypothesis that primary adaptive strategies (competitors, C; stress-tolerators, S; ruderals, R) are associated, respectively, with nitrogenous metabolites synthesized in persistent organs (alkaloids), nitrogen-lacking aromatic terpenes and phenolics, and nitrogenous compounds prevalent in reproductive tissues (cyanogenic glucosides and glucosinolates). A matrix was compiled of 1019 species for which secondary metabolite pathways and CSR strategies are known. Accounting for phylogenetic relatedness and native biomes, we found that most phytochemical pathways did not correlate with strategy axes, but certain key associations were evident. C-selection was positively associated with amino acid-derived phenylpropanoids (low phylogenetic relatedness; {lambda} <0.5) and pyrrolizidine alkaloids and galloyl derivatives (high {lambda}), and negatively with N-lacking linear monoterpenes (low {lambda}). Nitrogenous cyanogenic glucosides positively correlated with R-selection (low {lambda}). Terpenoids were widely distributed, but correlated positively with S- and negatively with R-selection (low {lambda}). Twenty-six correlations between phytochemicals and biomes (low {lambda}) were evident. Most secondary metabolite synthesis pathways are widespread, reflecting common roles and obligate defence, and strong phylogenetic effects are often evident. However, the character of phytochemical/adaptive strategy associations agrees with ecological theory and thus reflects adaptation.

ecology↗

bioRxiv2019

GUN1 influences the accumulation of NEP-dependent transcripts and chloroplast protein import in Arabidopsis cotyledons upon perturbation of chloroplast protein homeostasis

Correct chloroplast development and function require coordinated expression of chloroplast and nuclear genes. This is achieved through chloroplast signals that modulate nuclear gene expression in accordance with the chloroplasts needs. Genetic evidence indicates that GUN1, a chloroplast-localized pentatricopeptide-repeat (PPR) protein with a C-terminal Small MutS-Related (SMR) domain, is involved in integrating multiple developmental and stress-related signals in both young seedlings and adult leaves. Recently, GUN1 was found to interact physically with factors involved in chloroplast protein homeostasis, and with enzymes of tetrapyrrole biosynthesis in adult leaves that function in various retrograde signaling pathways. Here we show that, following perturbation of chloroplast protein homeostasis i) by growth in lincomycin-containing medium, or ii) in mutants defective in either the FtsH protease complex (ftsh), plastid ribosome activity (prps21-1 and prpl11-1) or plastid protein import and folding (cphsp70-1), GUN1 influences NEP-dependent transcript accumulation during cotyledon greening and also intervenes in chloroplast protein import.

plant biology↗