Biology subjects

Barros, P. M.

Publications and source records attributed to Barros, P. M..

7 recordsLinked to original sources

bioRxiv2026

Evolutionary and functional diversification of cork oak NLRs reveals RNL expansion and dual roles in biotic and abiotic stress

The Nucleotide-Binding Domain Leucine-Rich Repeat (NLR) gene family is a central component of plant immune systems, yet its diversity and evolutionary dynamics remain poorly characterized in long-lived tree species. Here, we performed a genome-wide analysis of the NLR gene family in Quercus suber (cork oak) using InterNLR, a new annotation tool, and explored their expression regulation in response to biotic and abiotic stresses. A total of 918 NLR and NLR-like genes were identified, encompassing both canonical and non-canonical members. Phylogenetic analyses based on the NB-ARC domain highlighted the distinct evolutionary trajectory of RNL proteins, which function as helper NLRs and show evidence of clade-specific gene duplication. Transcriptomic analyses revealed pronounced tissue-specific expression patterns, with RNLs exhibiting significantly elevated expression in xylem, suggesting a specialized role in this tissue. Under drought stress, seven NLR genes were differentially expressed and shared orthology with known abiotic stress-responsive genes. Notably, a CNL gene (LOC111996439) responded to both biotic and abiotic stresses, indicating a potential role as an integrative regulator of early defence responses, while an ADR1 orthologue (LOC112022539) suggests molecular crosstalk between stress signaling pathways. Population genetic analyses further revealed signatures of both positive and balancing selection acting on NLR genes. Together, these results provide new insights into the evolution, expression, and functional diversification of NLRs in cork oak. This work advances our understanding of immune gene architecture in an ecologically and economically important forest tree species.

plant biology↗

bioRxiv2025

Whole-genome polymorphisms and relatedness of rice varieties circulating in the Mediterranean market

Rice cultivation in Europe is declining as consumers increasingly prefer imported exotic varieties, such as aromatic and basmati rice, which are prone to fraudulent varietal claims due to their higher market value. To address this issue, we sequenced 20 high-value rice cultivars circulating in the Mediterranean market, analyzing their phylogeny and whole-genome polymorphisms. Our results revealed that two basmati varieties are genetically closer to two Mediterranean varieties, and that no direct link exists between genome-wide single nucleotide polymorphism (SNP) patterns and the rice commercial category. We further discuss genes located in previously described quantitative trait loci (QTLs) related to eating quality and seed properties. A variant in the WX1 gene, associated with higher amylose content, was found in both the Basmati group and Mediterranean varieties. Additionally, a SNP that could disrupt the drought tolerance gene OsbHLH148 was identified in five European varieties, while a variant affecting splicing of OsPol lambda, related to drought response, was present in four of those. This data could assist certification offices in reducing fraud in the rice market and provide valuable insights for researchers and breeders, particularly regarding the production, consumption, and adaptation of these cultivars to the Mediterranean region.

genomics↗

bioRxiv2024

OsbHLH089 and OsbHLH094 Modulate OsSLR1 Levels to Maintain Male Reproductive Fitness in Rice

DELLA proteins are a unique class of transcriptional regulators in plants, playing critical roles in diverse biological processes. Far from being only negative regulators of the Gibberellin (GA) signalling pathway, DELLAs act as central signalling hubs due to their versatile binding capacity and responsiveness to GA fluctuations. This adaptability allows DELLAs to interact with a wide array of proteins but also makes their functional study challenging: disruptions in DELLA function lead to pleiotropic effects across multiple pathways. To address this complexity, understanding DELLA interactors provides valuable insights into DELLAs nuanced functions and regulation. Building on this approach, we investigated novel OsSLR1 interactors, OsbHLH089 and OsbHLH094, members of the basic-helix-loop-helix transcription factor family. Our findings reveal that OsbHLH089 and OsbHLH094 are expressed in mature pollen grains, with the Osbhlh089/94 double mutant displaying smaller, indehiscent anthers and non-viable pollen, indicating their redundant role in pollen development during its late stages. Through ChIP-Seq and RNA-Seq analyses, we identified five target genes repressed by OsbHLH089 and OsbHLH094 (OsTDL1A, OsSPS1, OsDGD2{beta}, OspPGM, and OsDPE2) that are essential for pollen and anther development. Interestingly, we also observed the binding of these TFs to the OsSLR1 promoter. Notably, while other target genes were repressed, OsSLR1 was induced, with a significant protein accumulation in the double mutant compared to the Kitaake background in the late stages of pollen development. This suggests that OsSLR1 accumulation may compromise pollen viability, further highlighting the critical regulatory role of OsbHLH089 and OsbHLH094 in repressing OsSLR1 levels for proper pollen and anther development.

plant biology↗

bioRxiv2024

Comparative transcriptomics of Lathyrus sativus reveals accession-specific resistance responses against Erysiphe pisi

Lathyrus sativus (grass pea) is a valuable crop for sustainable agriculture, offering both dietary benefits and desirable agronomic traits. However, its yield stability is limited by different diseases such as powdery mildew caused by Erysiphe pisi. Frequent fungal resistance to pesticides and growing environmental concerns highlight the need for research investment to develop resistant crop varieties. Four L. sativus accessions, exhibiting varying levels of resistance to E. pisi (resistant, partially resistant, partially susceptible, and susceptible), were analysed using dual RNA-seq to identify key defence mechanisms and effector genes involved in this plant-pathogen interaction. The dual transcriptomic analysis highlighted a host biphasic response, characterised by an initial burst of gene expression, followed by a quiescent phase, and a second wave of intense gene expression at 72 hours after inoculation. Common L. sativus defence mechanisms, including antifungal protein expression, cell wall reinforcement, reactive oxygen species-mediated defence were activated by all accessions compared to susceptible accession. Unique responses in the resistant accession integrate early reinforcement of structural barriers with sustained chemical defences and stress responses. Overall, the partially resistant accession exhibited a front-loaded defence response, focused on biotic stimuli and interspecies interactions at early infection stages. In contrast, partial susceptible accessions exhibited a weaker baseline defence system, with a slower and less robust response specifically targeting pathogen infection. We identified potential E. pisi effectors, including genes involved in cell wall hydrolysis, nutrient acquisition, and virulence, with a higher diversity of effectors identified in the susceptible accession. This study identifies novel targets within the complex defence mechanisms of the Lathyrus sativus-Erysiphe pisi interaction that will support to future breeding programs aimed at enhancing resistance to E. pisi in L. sativus and other related species.

plant biology↗

bioRxiv2023

Drought impact on phellem development: identification of novel gene regulators and evidence of photosynthetic activity

Quercus suber (cork oak) is a sustainably exploited forest resource, producing a unique renewable raw material known as cork. With drought events imposing a negative impact on tree vitality, we need more knowledge on the genetic and environmental regulation of cork development to protect the cork sector. We focused on characterizing long-term drought-induced molecular adaptations occurring in stems, and identifying key genetic pathways regulating phellem development. One-year-old cork oak plants were grown for 6 months under well-watered, or water-deficit (WD) conditions and main stems were targeted for histological characterization and transcriptomic analysis. WD treatment impaired secondary growth, by reducing meristem activity at both vascular cambium and phellogen. We analyzed the transcriptional changes imposed by WD in phellem, inner bark, and xylem, and found a global downregulation of genes related to cell division, differentiation, and cell wall biogenesis. Phellem and inner bark showed upregulation of photosynthesis-related genes, highlighting a determinant role of stem photosynthesis in the adaptation to long-term drought. We show that developing phellem cells contain chloroplasts and their abundance increases under WD. Finally, we propose new candidate regulatory genes involved in the regulation of phellogen activity and demonstrate the involvement of phellem in drought-induced bark photosynthesis in young plants. HighlightPhellem development in cork oak is impaired in drought adaptation, by negative regulation of cell division and differentiation programs, while photosynthesis is induced to contributing to CO2 recycling in the stem.

plant biology↗

bioRxiv2020

SUMOylation of rice DELLA SLR1 modulates transcriptional responses and improves yield under salt stress

DELLA proteins modulate GA signalling and are major regulators of plant plasticity to endure stress. DELLAs are mostly regulated at the post-translational level, and their activity relies on the interaction with upstream regulators and transcription factors (TFs). SUMOylation is a post-translational modification (PTM) capable of changing protein interaction and found to influence DELLA activity in Arabidopsis. We determined that SUMOylation of the single rice DELLA SLENDER RICE1 (SLR1) occurs in a lysine residue different from the one previously identified in Arabidopsis REPRESSOR OF GA (RGA). Remarkably, artificially increasing SUMOylated SLR1 (SUMO1SLR1) levels attenuated the penalty of salt stress on plant yield. Gene expression analysis revealed that the overexpression of SUMOylated SLR1 regulates key dioxygenases that modulate active GA levels, namely GA20ox2 and GA2ox3, which could partially explain the sustained productivity upon salt stress imposition. Besides, SLR1 SUMOylation blocked the interaction with the growth regulator YAB4, which may fine-tune GA20ox2 expression. Mechanistically, we propose that SLR1 SUMOylation disrupts the interaction with members of several transcription factor families to modulate gene expression. We found that SLR1 SUMOylation represents a novel mechanism modulating DELLA activity, which attenuates the impact of stress on plant performance. One sentence summaryRice plants show increased yield under salt stress when its gibberellin transcriptional regulator DELLA protein is artificially SUMOylated.

plant biology↗

bioRxiv2018

Synergistic binding of bHLH transcription factors to the promoter of the maize NADP-ME gene used in C4 photosynthesis is based on an ancient code found in the ancestral C3 state

C4 photosynthesis has evolved repeatedly from the ancestral C3 state to generate a carbon concentrating mechanism that increases photosynthetic efficiency. This specialised form of photosynthesis is particularly common in the PACMAD clade of grasses, and is used by many of the worlds most productive crops. The C4 cycle is accomplished through cell-type specific accumulation of enzymes but cis-elements and transcription factors controlling C4 photosynthesis remain largely unknown. Using the NADP-Malic Enzyme (NADP-ME) gene as a model we aimed to better understand molecular mechanisms associated with the evolution of C4 photosynthesis. Two basic Helix-Loop-Helix (bHLH) transcription factors, ZmbHLH128 and ZmbHLH129, were shown to bind the C4 NADP-ME promoter from maize. These proteins form heterodimers and ZmbHLH129 impairs trans-activation by ZmbHLH128. Electrophoretic mobility shift assays indicate that a pair of cis-elements separated by a seven base pair spacer synergistically bind either ZmbHLH128 or ZmbHLH129. This pair of cis-elements is found in both C3 and C4 species of the PACMAD clade. Our analysis is consistent with this cis-element pair originating from a single motif present in the ancestral C3 state. We conclude that C4 photosynthesis has co-opted an ancient C3 regulatory code built on G-box recognition by bHLH to regulate the NADP-ME gene. More broadly, our findings also contribute to the understanding of gene regulatory networks controlling C4 photosynthesis.

plant biology↗