Heterotrimeric G-proteins, comprising Gα, Gβ, and Gγ subunits, act as crucial molecular switches for signaling transduction in all eukaryotic organisms. Through precise modulation of specific receptors or effectors coupled with heterotrimeric G-proteins in signaling cascades, plants have the capability to activate or suppress unique signaling pathways necessary for plant growth, development, and stress responses. This review provides an overview of the heterotrimeric G-proteins signaling pathway obtained to date, and highlights novel areas for future exploration and agricultural application based on the emerging significance and potential of heterotrimeric G proteins in regulating plant development and responses to abiotic stress.
Mercury (Hg), arsenic (As), cadmium (Cd), lead (Pb) and other toxic heavy metals (HM) pose significant risks to the environment, negatively impacting the morpho-physiological and biological traits of plants. At present, toxic elements constitute a significant proportion of the food chain, exerting an impact on human health due to their mobility and biomagnification. The metal exclusion biological technique stands out for its robust performance, even when dealing with extremely low metal concentrations. Its eco-friendly nature and cost-effectiveness further enhance its value. Due to the exponential growth pattern of bacteria, these exhibit high metal persistence and are recommended for metal exclusion processes. Moreover, vacuoles like vesicles present in mycorrhizal fungi can hold extremely high levels of HM. Microbe-assisted phytoremediation primarily occurs through two mechanisms: through the direct provision of the essential nutrients and phytohormones, such as plant growth regulators, siderophores, enzymes, and mineral; or indirectly by modulating the metal detoxification process. This indirect mechanism involves microbes aiding in the accumulation and sequestration of metals in plants through the secretion of specific extracellular substances like organic acids, biosurfactants, and chelators. Moreover, the metal bioavailability and translocation in the rhizosphere are also altered via various mechanisms like acidification, precipitation, complexation or redox reactions. The understanding of the molecular and physiological processes underpinning the functions of arbuscular mycorrhizal fungi (AMF) in reducing HM toxicity, improving plant performance by procuring nutrients under HM-toxicity has significantly improved in recent years. In this review, adaptive and persistent methods related to physiological and cross-protective mechanisms in bacteria and mycorrhizal fungi (MF) resulting from the evolutionary consequences of dealing with HM toxicity have been addressed. Furthermore, the article offers details on the physiological and molecular reactions of host plants with fungi, and bacteria to HM stress, which may be useful for unveiling new knowledge about the strategies of HMs remediation.
Abscisic acid (ABA), a pivotal plant hormone once primarily associated with stress response, is now increasingly acknowledged for its indispensable role in plant development. This comprehensive review delves into the multifaceted functions of ABA in regulating various aspects of plant growth and development. From inhibiting germination to orchestrating seedling establishment, flowering time, and dormancy induction, ABA emerges as a central player in shaping plant developmental transitions. Unraveling the intricate regulatory mechanisms governing the ABA signaling pathway provides valuable insights into how plants adapt to environmental challenges while effectively managing their growth and reproductive strategies. This expanding knowledge not only highlights the significance of ABA in plant biology but also has profound implications for enhancing agricultural practices.
Juglans regia, an important economic tree species, is planted all over the world, and drought is one of the crucial factors limiting its growth and development. The various polyphenol content in walnut plants constitutes one of the material bases for the differences in stress resistance among various germplasms. However, the molecular mechanism underlying stress response mediated by polyphenol -dependent pathways remains unclear. v-Myb avian myeloblastosis viral oncogene homolog (MYB) protein of transcription factors play important regulatory roles in the process of plant stress responses. Previously, we identified JrMYB44 could be involved in osmotic stress response in walnut. In this study, we confirmed that the drought resistance of four walnut cultivars (‘Chandler’, ‘Xiangling’, ‘Xilin2’ and ‘Xifu1’) is positively correlated with the accumulation of polyphenols. The content and component changes of polyphenols in JrMYB44 overexpression (OE) and suppression (SE) lines in both walnut and Arabidopsis thaliana demonstrated that JrMYB44 positively regulated polyphenols accumulation. The variation of JrMYB44 expression and polyphenol levels under drought treatment indicated significant correlation between JrMYB44-induced drought tolerance and polyphenol accumulation, which was involved in reactive oxidative species (ROS) balance. The differentially expressed genes (DEGs) between OE and WT implied that JrMYB44 could positively activate downstream genes to participate in the drought stress response. Yeast one-hybrid (Y1H), transient GUS expression assay and dual-luciferase reporter assay (DLR) confirmed that JrMYB44 could recognize downstream JrWRKY7 and JrDREB2A, two transcription factors previously reported to be involved in drought response. Meanwhile, it was confirmed by Y2H, GST-pull down and luciferase complementation imaging assay (LCI) that JrMYB44 could interact with JrMYC2 and JrDof1, another two previously reported potential drought response regulators. Collectively, these results indicated that JrMYB44 could activate JrWRKY7, JrDREB2A and interact with JrMYC2 and JrDof1 to promote walnut polyphenol accumulation and improve drought resistance in a ROS dependent manner.
Nitrogen (N), phosphorus (P) or potassium (K) deficiency in plants can lead to a decrease in amino acid and protein synthesis. However, it is unknown how protein translation gets repressed during macronutrient deficiencies. Previous research has shown that general control non-depressible 1 (GCN1) cooperate with GCN2 to phosphorylate the alpha subunit of eukaryotic translation initiation factor (eIF2α). In this study, we observed phosphorylation of eIF2α under N, P, and K deficiencies, which was found to be lost in gcn1. Mutant gcn1 displayed higher sensitivity to macronutrient deficiencies compared to the wild-type (WT). The evidence of in situ reactive oxygen species (ROS) accumulation in leaves indicated that macronutrient starvation triggers ROS production. Treatment with Dimethylthiourea (DMTU), a ROS scavenger, eliminated ROS and reversed eIF2α phosphorylation induced by nutrient deficiency. Moreover, it was discovered that protein translation was reduced under N or K deficiency in the WT but not in gcn1, whereas under P deprivation, protein translation was reduced in both the WT and gcn1. We additionally found that DMTU can partially recover translation inhibition under N or K deprivation. Taken together, it is concluded that GCN1-GCN2-eIF2α pathway is regulated by ROS and is essential for plant survival under macronutrient starvation conditions.
Plants, as sessile organisms, must adapt to a range of abiotic stresses, including drought, salinity, heat, and cold, which are increasingly exacerbated by climate change. These stresses significantly impact crop productivity, posing challenges for sustainable agriculture and food security. Recent advances in omics studies and genetics have shed light on molecular mechanisms underlying plant stress responses, including the role of calcium (Ca2⁺) signaling, liquid–liquid phase separation (LLPS), and cell wall-associated sensors in detecting and responding to environmental changes. However, gaps remain in understanding how rapid stress signaling is integrated with slower, adaptive processes. Emerging evidence also highlights crosstalk between abiotic stress responses, plant immunity, and growth regulation, mediated by key components such as RAF-SnRK2 kinase cascades, DELLA proteins, etc. Strategies to enhance crop stress resistance without compromising yield include introducing beneficial alleles, spatiotemporal optimization of stress responses, and decoupling stress signaling from growth inhibition. This review emphasizes the importance of interdisciplinary approaches and innovative technologies to bridge fundamental research and practical agricultural applications, aiming to develop resilient crops for sustainable food production in an era of escalating environmental challenges.