Biology subjects

Lascano, H. R.

Publications and source records attributed to Lascano, H. R..

5 recordsLinked to original sources

bioRxiv2026

Selective autophagy promotes bacterial immunity under warming through NBR1-dependent regulation of ABI5

Elevated temperatures compromise plant immunity and increase susceptibility to bacterial pathogens through extensive reprogramming of hormone signaling pathways. Although autophagy contributes to both stress adaptation and pathogen defense, its role in hormone-dependent immune regulation under warm conditions remains unclear. Here, we investigated the contribution of NBR1 (NEIGHBOR OF BRCA1 GENE 1)-mediated selective autophagy to Arabidopsis immunity against Pseudomonas cannabina pv. alisalensis at elevated temperature. Bacterial infection under warming enhanced autophagic flux and promoted NBR1 turnover, indicating increased autophagic activity. Analysis of atg5 and nbr1 mutants, and NBR1-overexpressing lines, demonstrated that both core autophagy and NBR1-mediated selective autophagy contribute to bacterial immunity under warm conditions. Hormone and gene expression analyses indicated that NBR1 negatively regulates abscisic acid (ABA)-associated transcriptional responses during infection, while salicylic acid signaling was largely unaffected. Mechanistically, NBR1 physically associated with the ABA-responsive transcription factor ABI5 (ABA INSENSITIVE 5) and promoted its autophagy-dependent turnover in planta. ABI5 turnover was strongly reduced under warm conditions, leading to its accumulation in nbr1 and atg5 plants. Consistent with a functional role for ABI5 in this phenotype, genetic disruption of ABI5 largely reversed the increased susceptibility of nbr1 mutants at elevated temperature, whereas ABI5 overexpression increased susceptibility to bacterial infection. Together, our results identify NBR1-mediated selective autophagy as a regulatory mechanism that restrains ABA-associated susceptibility through the autophagy-dependent turnover of ABI5. These findings reveal a previously unrecognized connection between selective autophagy and ABA-dependent immune regulation and identify NBR1-mediated ABI5 turnover as a temperature-dependent mechanism that prevents stronger bacterial susceptibility under warm conditions.

plant biology↗

bioRxiv2025

Systemic resistance to pathogens in Arabidopsis requires HASTY-dependent miRNA cell-to-cell movement.

Plant defenses against pathogens are tightly regulated through complex gene expression control mechanisms. The precise activation and repression of defense-related genes are crucial to balancing the trade-off between growth and immunity. Micro RNAs (miRNAs) play a well-established role in the local regulation of plant-microbe interactions. While some miRNAs are also essential for systemic defense responses, their mechanisms of action, biogenesis, and long-distance mobility remain largely unexplored. Here, we show that HASTY (HST), a key factor in miRNA biogenesis and intercellular movement, is required for systemic defense activation. The impaired mobility of miRNAs in hst mutants correlates with a lack of systemic responses. In infected tissues, HST may enhance the co-transcriptional processing of specific pri-miRNAs, which promotes the cell-to-cell movement of their mature miRNAs and contributes to the activation of systemic defenses. Furthermore, two miRNAs that exhibit increased mobility during systemic defense induction are required for a proper systemic response. Interestingly, complementing hst mutants with a version of HST expressed exclusively in companion cells is sufficient to restore systemic defense induction, highlighting the role of miRNA cell-to-cell movement. These findings shed light on the role of HST in plant immunity, linking miRNA biogenesis and mobility to the fine-tuned regulation of systemic defenses.

molecular biology↗

bioRxiv2023

DIFFERENTIAL EFFECTS OF REACTIVE OXYGEN SPECIES ON AUTOPHAGY IN ARABIDOPSIS

Autophagy plays a key role in the responses to different stress condition in plants. Reactive oxygen species (ROS) are common modulators of stress responses, having both toxic and signaling functions. In this context, the relationship between ROS and autophagy regulation remains unclear, and in some aspects, contradictory. In this study, we employed pharmacological and genetic approaches to investigate the effects of different ROS on the cytoplastic redox state and autophagic flux in Arabidopsis thaliana. Ours results demonstrated that oxidative treatments with H2O2 and MV, which drastically increased the oxidized state of the cytoplasm, reduced the autophagic flux. Conversely, singlet oxygen, which did not have significant effects on the cytoplasmic redox state, increased the autophagic flux. Additionally, our findings indicated that after H2O2 and high light treatments and during the recovery period, the cytoplasm returned to its reduced state, while autophagy was markedly induced. In summary, our study unveils the differential effects of ROS on the autophagic flux, establishing a correlation with the redox state of the cytoplasm. Moreover, it emphasizes the dynamic nature of autophagy in response to oxidative stress and the subsequent recovery period. HIGHLIGHTSO_LIThis research shows the differential effects of reactive oxygen species on autophagic modulation, highlighting their impact on the cytoplasmic redox state. The relationship between ROS and autophagy regulation remains unclear, and in some aspects contradictory. Here, we present a comprehensive investigation characterizing the effects of different ROS, such as hydrogen peroxide and singlet oxygen, on the modulation of autophagy in Arabidopsis. In brief, our findings reveal differential impacts on cytoplasmic redox states and autophagic flux, providing insight into the dynamic nature of autophagy, especially in stress and post-stress conditions. C_LIO_LITo the best of our knowledge, our work is the first to evaluate autophagic flux both during and after oxidative stress in plants. Our results indicate that this differentiation is crucial when analyzing the effects of oxidative stress on autophagy. C_LI

cell biology↗

bioRxiv2019

Evolutionary insights into PtdIns3P signaling through FYVE and PHOX effector proteins from the moss Physcomitrella patens.

Phosphatidylinositol 3-phosphate (PtdIns3P) is one of the five different phosphoinositides (PPIs) species in plant cells, which regulate several aspects of plant growth and development, as well as responses to biotic and abiotic stresses. The mechanistic insights underlying PtdIns3P mode of action, specifically through PtdIns3P-binding effectors such as FYVE and PHOX proteins have been partially explored in plants with main focus on Arabidopsis thaliana. Additionally, they have been underexplored in other plant organisms such as bryophytes, the earliest diverging group of terrestrial flora.\n\nIn this study, we searched for genes coding for FYVE and PHOX domains containing sequences from different photosynthetic organisms in order to gather evolutionary insights on these PPI binding domains, followed by an in silico characterization of the FYVE and PHOX gene family in the moss Physcomitrella patens. Phylogenetic analysis showed that PpFYVE proteins can be grouped in 7 subclasses, with an additional subclass whose FYVE domain was lost during evolution to higher plants. On the other hand, PpPHOX proteins are classified into 5 subclasses. Expression analyses based on RNAseq data together with the analysis of cis-acting regulatory elements and transcription factor binding sites in promoter regions suggest the importance of these proteins in regulating stress responses but mainly developmental processes in P. patens. The results provide valuable information and robust candidate genes for future functional analysis aiming to further explore the role of this signaling pathway mainly during growth and development of tip growing cells and during the transition from 2D to 3D growth, which could provide ancestral regulatory players undertaken during plant evolution.

plant biology↗

bioRxiv2018

Increased oxidative stress tolerance by Superoxide dismutase overexpression in Mesorhizobium loti.

Drought and salinity conditions are the major factors affecting nitrogen fixation by legume-rhizobium symbiosis. A global response to these stress conditions is the increase of intracellular ROS leading to activation of antioxidant system to ensure cellular homeostasis. Under the hypothesis that overexpression of sod gene in M. loti improve tolerance to oxidative stress we decide to investigate the response of constitutive overexpression of the Mesorhizobium loti MAFF303099 sod gene on tolerance to oxidative stress under free-living conditions. The gene mlr7636 was overexpressed constitutively under the nptII promoter of pFAJ1708 plasmid. Our study revealed that the sod overexpressing mutant had five-fold increased SOD activity in periplasmic space and a better tolerance to superoxide and hydrogen peroxide in bacterial killing assays.\n\nIMPORTANCEIn this study, we report that the homologous superoxide dismutase overexpression in Mesorhizobium loti improves its tolerance to oxidative stress under free-living conditions.

microbiology↗