Biology subjects

Lozano-Duran, R.

Publications and source records attributed to Lozano-Duran, R..

28 records · Page 2Linked to original sources

bioRxiv2021

Geminiviral genomes encode additional proteins with specific subcellular localizations and virulence function

Geminiviruses are plant viruses with limited coding capacity. Geminivirus-encoded proteins were identified applying a 10-kDa arbitrary threshold; however, it is increasingly clear that small proteins play relevant roles in biological systems, which calls for the reconsideration of this criterion. Here, we show that geminiviral genomes contain additional ORFs. Using tomato yellow leaf curl virus, we demonstrate that some of these novel ORFs are expressed during the infection, and that the encoded proteins display specific subcellular localizations. We prove that the largest of these new ORFs, which we name V3, is required for full viral infection, and that the V3 protein localizes in the Golgi apparatus and functions as an RNA silencing suppressor. These results imply that the repertoire of geminiviral proteins can be expanded, and that getting a comprehensive overview of the molecular plant-geminivirus interactions will require the detailed study of small ORFs so far neglected.

plant biology↗

bioRxiv2020

Host-interactor screens of Phytophthora infestans RXLR proteins reveal vesicle trafficking as a major effector-targeted process

Pathogens modulate plant cell structure and function by secreting effectors into host tissues. Effectors typically function by associating with host molecules and modulating their activities. This study aimed to identify the host processes targeted by the RXLR class of host-translocated effectors of the potato blight pathogen Phytophthora infestans. To this end, we performed an in planta protein-protein interaction screen by transiently expressing P. infestans RXLR effectors in Nicotiana benthamiana leaves followed by co-immunoprecipitation (co-IP) and liquid chromatography tandem mass spectrometry (LC-MS/MS). This screen generated an effector-host protein interactome matrix of 59 P. infestans RXLR effectors x 586 N. benthamiana proteins. Classification of the host interactors into putative functional categories revealed over 35 biological processes possibly targeted by P. infestans. We further characterized the PexRD12/31 family of RXLR-WY effectors, which associate and co-localize with components of the vesicle trafficking machinery. One member of this family, PexRD31, increased the number of FYVE positive vesicles in N. benthamiana cells. FYVE positive vesicles also accumulated in leaf cells near P. infestans hyphae, indicating that the pathogen may enhance endosomal trafficking during infection. We anticipate that the interactome dataset we generated will serve as a useful community resource for functional studies of P. infestans effectors and of effector-targeted host processes.

plant biology↗

bioRxiv2020

Plant DNA polymerases alpha and delta mediate replication of geminiviruses

Geminiviruses are causal agents of devastating diseases in crops. Geminiviruses have circular single-stranded (ss)DNA genomes that are replicated in the nucleus of the infected plant cell through double-stranded (ds)DNA intermediates by the plants DNA replication machinery; which host DNA polymerase mediates geminiviral multiplication, however, has so far remained elusive. Here, we show that subunits of the nuclear replicative DNA polymerases and {delta} physically interact with the geminivirus-encoded replication enhancer protein, C3, and are required for viral replication. Our results suggest that while DNA polymerase is essential to generate the viral dsDNA intermediate, DNA polymerase {delta} mediates the synthesis of new copies of the geminiviral ssDNA genome, and that the virus-encoded C3 acts selectively recruiting DNA polymerase {delta} over {varepsilon} to favour a productive replication.

plant biology↗

bioRxiv2019

A novel pathway linking plasma membrane and chloroplasts is co-opted by pathogens to suppress salicylic acid-dependent defences

Chloroplasts are crucial players in the activation of defensive hormonal responses during plant-pathogen interactions. Here, we show that a plant virus-encoded protein re-localizes from the plasma membrane to chloroplasts upon triggering plant defence, interfering with the chloroplast-dependent activation of anti-viral salicylic acid (SA) biosynthesis. Strikingly, we have found that plant pathogens from different kingdoms seem to have convergently evolved to target chloroplasts and impair SA-dependent defences following an association with membranes, which is based on the co-existence of two subcellular targeting signals, an N-myristoylation site and a chloroplast transit peptide. This pattern is also present in plant proteins, at least one of which conversely activates SA defences from the chloroplast. Taken together, our results suggest that a pathway linking plasma membrane to chloroplasts and activating defence exists in plants, and that such pathway has been co-opted by plant pathogens during host-pathogen co-evolution to promote virulence through suppression of SA responses.

plant biology↗

bioRxiv2019

A virus-encoded protein suppresses methylation of the viral genome through its interaction with AGO4 in the Cajal body

In plants, establishment of de novo DNA methylation is regulated by the RNA-directed DNA methylation (RdDM) pathway. RdDM machinery is known to concentrate in the Cajal body, but the biological significance of this localization has remained elusive. Here, we show that the anti-viral methylation of the Tomato yellow leaf curl virus (TYLCV) genome occurs specifically in the Cajal body of Nicotiana benthamiana cells. Methylation of the viral genome is countered by a virus-encoded protein, V2, which interacts with the central RdDM component AGO4, interfering with its binding to the viral DNA; Cajal body localization of the V2-AGO4 interaction is required for the viral protein to exert this function. Taken together, our results draw a long sought-after functional connection between RdDM, the Cajal body, and anti-viral DNA methylation, paving the way for a deeper understanding of DNA methylation and anti-viral defences in plants.

plant biology↗

bioRxiv2019

The receptor-like kinases BAM1 and BAM2 promote the cell-to-cell movement of miRNA in the root stele to regulate xylem patterning

Xylem patterning in the root is established through the creation of opposing gradients of miRNAs and their targets, enabled by the cell-to-cell spread of the former. The miRNAs involved in xylem patterning, miR165/6, move through plasmodesmata, but how their trafficking is regulated remains elusive. Here, we describe that the receptor-like kinases BAM1/2 are required for the intercellular movement of miR165/6 in the stele and hence proper xylem patterning in the root.

plant biology↗

bioRxiv2019

PLANT NATRIURETIC PEPTIDE A antagonizes salicylic acid-primed cell death

Peptide hormones perceived in the cell surface via receptor proteins enable cell-to-cell communication and act in multiple biological processes through the activation of intracellular signaling. Even though Arabidopsis is predicted to have more than 1,000 secreted peptides, the biological relevance of the majority of these is yet to be established. Here, we demonstrate that PLANT NATRIURETIC PEPTIDE A (PNP-A), a functional analog to vertebrate atrial natriuretic peptides, antagonizes the salicylic acid (SA)-mediated cell death in the Arabidopsis lesion-stimulating disease 1 (lsd1) mutant. While loss of PNP-A potentiates SA signaling, exogenous application of the PNP-A synthetic peptide or overexpression of PNP-A significantly compromises the SA-mediated cell death. Moreover, we identified a plasma membrane-localized receptor-like protein, which we name PNPAR (for PNP-A receptor), that binds PNP-A and is required to counteract SA responses. Our work identifies a novel peptide-receptor pair which modulates SA responses in Arabidopsis.

plant biology↗

bioRxiv2019

Phosphorylation-dependent routing of RLP44 towards brassinosteroid or phytosulfokine signalling

Plants rely on a complex network of cell surface receptors to integrate developmental and environmental cues into behaviour adapted to the conditions. The largest group of these receptors, leucine-rich repeat receptor-like kinases, form a complex interaction network that is modulated and extended by receptor-like proteins. This raises the question of how specific outputs can be generated when receptor proteins are engaged in a plethora of promiscuous interactions. RECEPTOR-LIKE PROTEIN 44 (RLP44) acts to promote both brassinosteroid and phytosulfokine signalling, which orchestrate a wide variety of cellular responses. However, it is unclear how these activities are coordinated. Here, we show that RLP44 is phosphorylated in its highly conserved C-terminal cytosolic tail and that this post-translational modification governs its subcellular localization. RLP44 variants in which phosphorylation is blocked enter endocytosis prematurely, leading to an almost entirely intracellular localization, whereas phospho-mimicking or ectopic phosphorylation results in preferential RLP44 localization at the plasma membrane. Phosphorylation of the C-terminus is essential for brassinosteroid-associated functions of RLP44. In contrast, RLP44s role in phytosulfokine signalling is not affected by its phospho-status. Detailed mutational analysis suggests that phospho-charge, rather than modification of individual amino acids determines routing of RLP44 to its target receptor complexes, providing a framework to understand how a common component of different receptor complexes can get specifically engaged in a particular signalling pathway.

plant biology↗

bioRxiv2018

The IMMUNE-ASSOCIATED NUCLEOTIDE-BINDING 9 protein is a regulator of basal immunity in Arabidopsis thaliana

A robust regulation of plant immune responses requires multitude of positive and negative regulators that act in concert. The immune-associated nucleotide-binding (IAN) gene family members are associated with immunity in different organisms, although no characterization of their function has been carried out to date in plants. In this work, we analyzed the expression patterns of IAN genes and found that IAN9 is repressed upon pathogen infection or treatment with immune elicitors. IAN9 encodes a plasma membrane-localized protein that genetically behaves as a negative regulator of immunity. A novel ian9 mutant generated by CRISPR/Cas9 shows increased resistance to Pseudomonas syringae, while transgenic plants overexpressing IAN9 show a slight increase in susceptibility. In vivo immunoprecipitation of IAN9-GFP followed by mass spectrometry analysis revealed that IAN9 associates with a previously uncharacterized C3HC4-type RING finger domain-containing protein that we named IAP1, for IAN9-associated protein 1, which also acts as a negative regulator of basal immunity. Interestingly, neither ian9 or iap1 mutant plants show any obvious developmental phenotype, suggesting that they display enhanced inducible immunity rather than constitutive immune responses. Since both IAN9 and IAP1 have orthologs in important crop species, they could be suitable targets to generate plants more resistant to diseases caused by bacterial pathogens without yield penalty.

plant biology↗

bioRxiv2017

A plant receptor-like kinase promotes cell-to-cell spread of RNAi and is targeted by a virus

RNA interference (RNAi) in plants can move from cell to cell, allowing for systemic spread of an anti-viral immune response. How this cell-to-cell spread of silencing is regulated is currently unknown. Here, we describe that the C4 protein from Tomato yellow leaf curl virus has the ability to inhibit the intercellular spread of RNAi. Using this viral protein as a probe, we have identified the receptor-like kinase (RLK) BARELY ANY MERISTEM 1 (BAM1) as a positive regulator of the cell-to-cell movement of RNAi, and determined that BAM1 and its closest homologue, BAM2, play a redundant role in this process. C4 interacts with the intracellular domain of BAM1 and BAM2 at the plasma membrane and plasmodesmata, the cytoplasmic connections between plant cells, interfering with the function of these RLKs in the cell-to-cell spread of RNAi. Our results identify BAM1 as an element required for the cell-to-cell spread of RNAi and highlight that signalling components have been co-opted to play multiple functions in plants.

plant biology↗