The involvement of gaseous signaling molecules in plant MAPK cascades: function and signal transduction

Genome-wide identification of the AP2/ERF gene family from Limonium bicolor and functional characterization of LbAP2/ERF32 under salt stress

AP2/ERF transcription factors (TFs) play important roles in plant growth and development, plant morphogenesis and response to environmental stresses. However, their biological roles in recretohalophytes are still not fully revealed. Limonium bicolor L. is a typical recretohalophyte, which secretes excessive salt ions through the salt glands on the epidermis. Here, 64 LbAP2/ERF genes were identified in L. bicolor genome, which were unevenly distributed on the eight chromosomes. Cis-elements related to growth and development, stress response and phytohormone response are distributed in multiple LbAP2/ERF promoters. Expression analysis indicated that LbAP2/ERF genes responsed to NaCl, PEG and ABA. And the salt gland density, salt secretion of leaves and overall salt tolerance of LbAP2/ERF32 silenced lines were significantly reduced. In agreement, the genes related to salt gland development and ion transport were significantly changed in LbAP2/ERF32-silenced lines. Our findings provided fundamental information on the structure and evolutionary relationship of LbAP2/ERF gene family in salt gland development and salt secretion of L. bicolor and gave theoretical guideline for further functional study of LbAP2/ERF genes in response to abiotic stress.

Uncovering the Mechanisms: The Role of Biotrophic Fungi in Activating or Suppressing Plant Defense Responses

This paper discusses the mechanisms by which fungi manipulate plant physiology and suppress plant defense responses by producing effectors that can target various host proteins. Effector-triggered immunity and effector-triggered susceptibility are pivotal elements in the complex molecular dialogue underlying plant-pathogen interactions. Pathogen-produced effector molecules possess the ability to mimic pathogen-associated molecular patterns or hinder the binding of pattern recognition receptors. Effectors can directly target nucleotide-binding domain, leucine-rich repeat receptors, or manipulate downstream signaling components to suppress plant defense. Interactions between these effectors and receptor-like kinases in host plants are critical in this process. Biotrophic fungi adeptly exploit the signaling networks of key plant hormones, including salicylic acid, jasmonic acid, abscisic acid, and ethylene, to establish a compatible interaction with their plant hosts. Overall, the paper highlights the importance of understanding the complex interplay between plant defense mechanisms and fungal effectors to develop effective strategies for plant disease management.

Atherosclerosis and Cardiovascular Complications in People Living with HIV: A Focused Review

The intersection of Human Immunodeficiency Virus (HIV) infection and cardiovascular disease (CVD) represents a significant area of concern; advancements in antiretroviral therapy (ART) have notably extended the life expectancy of people living with HIV (PLWH), concurrently elevating the prevalence of chronic conditions such as CVD. This paper explores the multifaceted relationship between HIV infection, ART, and cardiovascular health, focusing on the mechanisms by which HIV and ART contribute to increased cardiovascular risk, including the promotion of endothelial dysfunction, inflammation, immune activation, and metabolic disturbances. We highlight the critical roles of HIV-associated proteins-Tat, Nef, and gp120-in accelerating atherosclerosis through direct and indirect pathways that exacerbate endothelial damage and inflammation. Additionally, we address the persistent challenge of chronic inflammation and immune activation in PLWH, factors that are strongly predictive of non-AIDS-related diseases, including CVD, even in the context of effective viral suppression. The impact of ART on cardiovascular risk is examined, with particular attention to the metabolic implications of specific ART regimens, which can influence lipid profiles and body composition, thereby modifying CVD risk. The therapeutic potential of statins, aspirin, and emerging treatments such as PCSK9 inhibitors in mitigating cardiovascular morbidity and mortality among PLWH is discussed, alongside considerations for their use in conjunction with ART. Our review underscores the necessity for a comprehensive, multidisciplinary approach to cardiovascular care in PLWH, which integrates vigilant cardiovascular risk assessment and management with HIV treatment. As we navigate the evolving landscape of HIV care, the goal remains to optimize treatment outcomes while minimizing cardiovascular risk, ensuring that the gains in longevity afforded by ART translate into improved overall health and quality of life for PLWH.

Computational Analysis of Albaflavenone Interaction with SlMAPK1 for Drought Resistance in Tomato

As global agricultural challenges intensify, particularly drought stress, the exploration of innovative strategies for crop resilience has become crucial. This study focuses on the role of the microbial endophyte metabolite Albaflavenone in enhancing drought resistance in tomato (Solanum lycopersicum L.) through the activation of the SlMAPK1 protein in the MAPK pathway. To computationally analyze the interaction between Albaflavenone and SlMAPK1 and to elucidate the potential enhancement of drought tolerance in tomato plants through this interaction. We utilized molecular docking, homology modeling, and molecular dynamics simulations to investigate the binding affinities and interaction dynamics between SlMAPK1 and Albaflavenone. Functional network analysis was employed to examine protein-protein interactions within the MAPK pathway, while the MM-GBSA method was used to calculate binding free energies. Our computational analyses revealed that Albaflavenone exhibited a high binding affinity to SlMAPK1 with a binding energy of - 8.9 kcal/mol. Molecular dynamics simulations showed this interaction significantly stabilized SlMAPK1, suggesting enhanced activity. Specifically, the root mean square deviation (RMSD) of the Albaflavenone-SlMAPK1 complex stabilized at around 3.1 Å, while the root mean square fluctuations (RMSF) indicated consistent amino acid conformations. Additionally, the radius of gyration (Rg) analysis demonstrated minimal variance, suggesting a compact and stable protein-ligand complex. The significant binding affinity between Albaflavenone and SlMAPK1 highlights the potential of leveraging plant-microbe interactions in developing sustainable agricultural practices. These findings also demonstrate the effectiveness of computational methods in dissecting complex biological interactions, contributing to a deeper understanding of plant resilience strategies against environmental stresses.

Immunocompromisation of wheat host by L-BSO and 2,4-DPA induces susceptibility to the fungal pathogen Fusarium oxysporum

Susceptibility is defined as the disruption of host defence systems that promotes infection or limits pathogenicity. Glutathione (GSH) is a major component of defence signalling pathways that maintain redox status and is synthesised by γ-glutamyl cysteine synthetase (γ-ECS). On the other hand, lignin acts as a barrier in the primary cell wall of vascular bundles (VBs) synthesised by phenylalanine ammonia-lyase (PAL) in the intracellular system of plants. In this study, we used two inhibitors, such as L-Buthionine-sulfoximine (BSO), which irreversibly inhibits γ-ECS, and 2,4-dichlorophenoxyacetic acid (DPA), which reduces PAL activity and leads to the induction of oxidative stress in wheat (Triticum aestivum) seedlings after exposure to Fusarium oxysporum. Seedlings treated with 1 mM L-BSO and 2,4-DPA showed high levels of hydrogen peroxide (H2O2), malondialdehyde (MDA), carbonyl (CO) content, and low activity of antioxidative enzymes [superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APX), and glutathione reductase (GR)] as compared to wild-type (WT) seedlings under F. oxysporum infection. Further, the content of reduced glutathione (RGSH), ascorbate (ASC), and lignin was decreased in BSO and DPA treated seedlings as compared to WT seedlings during Fusarium infection. Moreover, treatment with BSO and DPA significantly inhibited the relative activity of γ-ECS and PAL (P ≤ 0.001) in WT seedlings during Fusarium infection, which led to disintegrated VBs and, finally, cell death. Our results demonstrate that inhibition of γ-ECS and PAL by BSO and DPA, respectively, disrupts the defence mechanisms of wheat seedlings and induces susceptibility to F. oxysporum.

Genome-wide identification of the mitogen-activated kinase gene family from Limonium bicolor and functional characterization of LbMAPK2 under salt stress

BACKGROUND

Mitogen-activated protein kinases (MAPKs) are ubiquitous signal transduction components in eukaryotes. In plants, MAPKs play an essential role in growth and development, phytohormone regulation, and abiotic stress responses. The typical recretohalophyte Limonium bicolor (Bunge) Kuntze has multicellular salt glands on its stems and leaves; these glands secrete excess salt ions from its cells to mitigate salt damage. The number, type, and biological function of L. bicolor MAPK genes are unknown.

RESULTS

We identified 20 candidate L. bicolor MAPK genes, which can be divided into four groups. Of these 20 genes, 17 were anchored to 7 chromosomes, while LbMAPK18, LbMAPK19, and LbMAPK20 mapped to distinct scaffolds. Structure analysis showed that the predicted protein LbMAPK19 contains the special structural motif TNY in its activation loop, whereas the other LbMAPK members harbor the conserved TEY or TDY motif. The promoters of most LbMAPK genes carry cis-acting elements related to growth and development, phytohormones, and abiotic stress. LbMAPK1, LbMAPK2, LbMAPK16, and LbMAPK20 are highly expressed in the early stages of salt gland development, whereas LbMAPK4, LbMAPK5, LbMAPK6, LbMAPK7, LbMAPK11, LbMAPK14, and LbMAPK15 are highly expressed during the late stages. These 20 LbMAPK genes all responded to salt, drought and ABA stress. We explored the function of LbMAPK2 via virus-induced gene silencing: knocking down LbMAPK2 transcript levels in L. bicolor resulted in fewer salt glands, lower salt secretion ability from leaves, and decreased salt tolerance. The expression of several genes [LbTTG1 (TRANSPARENT TESTA OF GL1), LbCPC (CAPRICE), and LbGL2 (GLABRA2)] related to salt gland development was significantly upregulated in LbMAPK2 knockdown lines, while the expression of LbEGL3 (ENHANCER OF GL3) was significantly downregulated.

CONCLUSION

These findings increase our understanding of the LbMAPK gene family and will be useful for in-depth studies of the molecular mechanisms behind salt gland development and salt secretion in L. bicolor. In addition, our analysis lays the foundation for exploring the biological functions of MAPKs in an extreme halophyte.

HIV-Related Atherosclerosis: State-of-the-Art-Review

The infection caused by the Human Immunodeficiency Virus (HIV) has spread rapidly across the globe, assuming the characteristics of an epidemic in some regions. Thanks to the introduction of antiretroviral therapy into routine clinical practice, there was a considerable breakthrough in the treatment of HIV, that is now HIV is potentially well-controlled even in low-income countries. To date, HIV infection has moved from the group of life-threatening conditions to the group of chronic and well controlled ones and the quality of life and life expectancy of HIV+ people, with an undetectable viral load is closer to that of an HIV- people. However, unsolved issues still persist. For example: people living with HIV are more prone to the age-related diseases, especially atherosclerosis. For this reason, a better understanding of the mechanisms of HIV-associated destabilization of vascular homeostasis seems to be an urgent duty, that may lead to the development of new protocols, bringing the possibilities of pathogenetic therapies to a new level. The purpose of the article was to evaluate the pathological aspects of HIV-induced atherosclerosis.

Transcriptome Reveals the Molecular Mechanism of the ScALDH21 Gene from the Desert Moss Syntrichia caninervis Conferring Resistance to Salt Stress in Cotton

The desert moss Syntrichia caninervis has proven to be an excellent plant material for mining resistance genes. The aldehyde dehydrogenase 21 (ScALDH21) gene from S. caninervis has been shown to confer tolerance to salt and drought, but it is unclear how the transgene ScALDH21 regulates tolerance to abiotic stresses in cotton. In the present work, we studied the physiological and transcriptome analyses of non-transgenic (NT) and transgenic ScALDH21 cotton (L96) at 0 day, 2 days, and 5 days after salt stress. Through intergroup comparisons and a weighted correlation network analysis (WGCNA), we found that there were significant differences between NT and L96 cotton in the plant hormone, Ca2+, and mitogen-activated protein kinase (MAPK) signaling pathways as well as for photosynthesis and carbohydrate metabolism. Overexpression of ScALDH21 significantly increased the expression of stress-related genes in L96 compared to NT cotton under both normal growth and salt stress conditions. These data suggest that the ScALDH21 transgene can scavenge more reactive oxygen species (ROS) in vivo relative to NT cotton and improve cotton resistance to salt stress by increasing the expression of stress-responsive genes, responding quickly to stress stimuli, enhancing photosynthesis and improving carbohydrate metabolism. Therefore, ScALDH21 is a promising candidate gene to improve resistance to salt stress, and the application of this gene in cotton provides new insights into molecular plant breeding.

Hydrogen Gas Improves the Postharvest Quality of Lanzhou Lily (Lilium davidii var. unicolor) Bulbs

Hydrogen gas (H₂) is an important molecular messenger in animal and plant cells and is involved in various aspects of plant processes, including root organogenesis induction, stress tolerance and postharvest senescence. This study investigated the effect of H₂ fumigation on the quality of Lanzhou lily scales. The results indicated the H₂ remarkably declined the color variation and browning degree in Lanzhou lily scales by suppressing the activity of phenylalanine ammonia-lyase (PAL), peroxidase (POD) and polyphenol oxidase (PPO). Moreover, H₂ significantly alleviated the degradation of soluble proteins and soluble sugars in Lanzhou lily scales during postharvest storage, mitigating the decline in nutritional quality. This alleviating effect of H₂ might be achieved by increasing the endogenous H₂ concentration. Collectively, our data provide new insights into the postharvest quality reduction of Lanzhou lily scales mitigated by H₂ fumigation.

Transcriptomic analysis provides insights into the algicidal mechanism of cocamidopropyl betaine against the red tide microalgae Skeletonema costatum

This study investigated the effect of the surfactant cocamidopropyl betaine (CAB) on the growth of red tide microalgae Skeletonema costatum. It was found that CAB caused cell lysis in a time- and dose-dependent manner and significantly inhibited the growth of S. costatum. Additionally, the transcriptomic approach was coupled with physiological analysis to elucidate the inhibitory mechanism of CAB on S. costatum. Among the 30726 genes identified, 17720 and 20583 genes were differentially expressed after treatment for 3 h and 6 h, respectively, which revealed that CAB redirected metabolic pathways, of which the expressions of genes related to the proteasome, ABC transporters, and amino acid-related metabolism were significantly upregulated, while genes involved in photosynthesis, biofilm and cell wall synthesis, mitogen-activated protein kinase (MAPK) cascades and antioxidant system were downregulated. The results above corresponded to the decreasing antioxidant enzymes activities, protein and photosynthetic pigments contents, as well as the increasing malondialdehyde (MDA) content. Our study presented herein shed light on the algicidal mechanism of CAB at the transcriptome level and was useful to red tide control, and marine environmental protection.

Role of pathogen's effectors in understanding host-pathogen interaction

Pathogens can pose challenges to plant growth and development at various stages of their life cycle. Two interconnected defense strategies prevent the growth of pathogens in plants, i.e., molecular patterns triggered immunity (PTI) and pathogenic effector-triggered immunity (ETI) that often provides resistance when PTI no longer functions as a result of pathogenic effectors. Plants may trigger an ETI defense response by directly or indirectly detecting pathogen effectors via their resistance proteins. A typical resistance protein is a nucleotide-binding receptor with leucine-rich sequences (NLRs) that undergo structural changes as they recognize their effectors and form associations with other NLRs. As a result of dimerization or oligomerization, downstream components activate "helper" NLRs, resulting in a response to ETI. It was thought that ETI is highly dependent on PTI. However, recent studies have found that ETI and PTI have symbiotic crosstalk, and both work together to create a robust system of plant defense. In this article, we have summarized the recent advances in understanding the plant's early immune response, its components, and how they cooperate in innate defense mechanisms. Moreover, we have provided the current perspective on engineering strategies for crop protection based on up-to-date knowledge.

Nitric Oxide Crosstalk With Phytohormone Is Involved in Enhancing Photosynthesis of Tetrastigma hemsleyanum for Photovoltaic Adaptation

Photovoltaic agriculture is a newly emerging ecological planting pattern. In view of the adverse effect on production, a better understanding of photovoltaic adaptation responses is essential for the development of the innovative agriculture mode in sustainable crop production. Here, we investigated the impact of photovoltaic condition on endogenous hormone composition and transcriptome profile of Tetrastigma hemsleyanum. A total of 16 differentially accumulated phytohormones and 12,615 differentially expressed genes (DEGs) were identified. Photovoltaic adaptation significantly decreased the contents of phytohormones especially salicylic acid (SA) and jasmonic acid (JA). DEGs were the most relevant to photosynthesis and mitogen-activated protein kinase (MAPK) signaling pathway especially the key genes encoding proteins involved in photosystem I (PS I) and photosystem II (PS II) reaction center. Nitric oxide (NO), JA, and SA treatment alone significantly enhanced the photosynthetic efficiency which was decreased by exposure to photovoltaic condition, but the combined treatment of "NO + SA" could weaken the enhancement effect by regulating the expression level of psaL, CHIL, petF1, psbQ, and psaE genes. Exogenous phytohormones and NO treatment mitigated the accumulation of reactive oxygen species (ROS) and potentiated antioxidant capacity, which would be weakened by the combined treatment of "NO + SA." SA and JA significantly decreased endogenous NO burst triggered by photovoltaic adaptation. SA might be a potent scavenger of NO and counter the restoration effect of NO on growth and photosynthetic potential in T. hemsleyanum. The results could provide reference for the application of phytohormones/other signaling molecules in photovoltaic agriculture.