Thaumatin-like proteins (TLPs) comprise a complex and evolutionarily conserved protein family that participates in host defense and several developmental processes in plants, fungi, and animals. Importantly, TLPs are plant host defense proteins that belong to pathogenesis-related family 5 (PR-5), and growing evidence has demonstrated that they are involved in resistance to a variety of fungal diseases in many crop plants, particularly legumes. Nonetheless, the roles and underlying mechanisms of the TLP family in legumes remain unclear. The present review summarizes recent advances related to the classification, structure, and host resistance of legume TLPs to biotic and abiotic stresses; analyzes and predicts possible protein–protein interactions; and presents their roles in phytohormone response, root nodule formation, and symbiosis. The characteristics of TLPs provide them with broad prospects for plant breeding and other uses. Searching for legume TLP genetic resources and functional genes, and further research on their precise function mechanisms are necessary.

As a fundamental metabolic pathway, autophagy plays important roles in plant growth and development, particularly under stress conditions. A set of autophagy-related (ATG) proteins is recruited for the formation of a double-membrane autophagosome. Among them, the essential roles of ATG2, ATG18, and ATG9 have been well established in plant autophagy via genetic analysis; however, the underlying molecular mechanism for ATG2 in plant autophagosome formation remains poorly understood. In this study, we focused on the specific role of ATG2 in the trafficking of ATG18a and ATG9 during autophagy in Arabidopsis (Arabidopsis thaliana). Under normal conditions, YFP-ATG18a proteins are partially localized on late endosomes and translocated to ATG8e-labeled autophagosomes upon autophagic induction. Real-time imaging analysis revealed sequential recruitment of ATG18a on the phagophore membrane, showing that ATG18a specifically decorated the closing edges and finally disassociated from the completed autophagosome. However, in the absence of ATG2, most of the YFP-ATG18a proteins are arrested on autophagosomal membranes. Ultrastructural and 3D tomography analysis showed that unclosed autophagosome structures are accumulated in the atg2 mutant, displaying direct connections with the endoplasmic reticulum (ER) membrane and vesicular structures. Dynamic analysis of ATG9 vesicles suggested that ATG2 depletion also affects the association between ATG9 vesicles and the autophagosomal membrane. Furthermore, using interaction and recruitment analysis, we mapped the interaction relationship between ATG2 and ATG18a, implying a possible role of ATG18a in recruiting ATG2 and ATG9 to the membrane. Our findings unveil a specific role of ATG2 in coordinating ATG18a and ATG9 trafficking to mediate autophagosome closure in Arabidopsis.

Mitochondrial homeostasis refers to the balance of mitochondrial number and quality in a cell. It is maintained by mitochondrial biogenesis, mitochondrial fusion/fission, and the clearance of unwanted/damaged mitochondria. Mitophagy represents a selective form of autophagy by sequestration of the potentially harmful mitochondrial materials into a double-membrane autophagosome, thus preventing the release of death inducers, which can trigger programmed cell death (PCD). Recent advances have also unveiled a close interconnection between mitophagy and mitochondrial dynamics, as well as PCD in both mammalian and plant cells. In this review, we will summarize and discuss recent findings on the interplay between mitophagy and mitochondrial dynamics, with a focus on the molecular evidence for mitophagy crosstalk with mitochondrial dynamics and PCD.

Phosphoenolpyruvate carboxylase (PEPC) is a ubiquitous cytosolic enzyme that catalyzes the irreversible β-carboxylation of phosphoenolpyruvate (PEP) in presence of HCO₃⁻ to produce oxaloacetate (OAA) during carbon fixation and photosynthesis. It is well accepted that PEPC genes are expressed in plants upon stress. PEPC also supports the biosynthesis of biocompatible osmolytes in many plant species under osmotic stress. There are five isoforms of PEPC found in peanut (Arachis hypogaea L.), namely, AhPEPC1, AhPEPC2, AhPEPC3, AhPEPC4, and AhPEPC5. Quantitative real-time polymerase chain reaction (qRT-PCR) analysis revealed that the gene expression patterns of these AhPEPC genes were different in mature seeds, stems, roots, flowers, and leaves. The expression of all the plant type PEPC (PTPCs) (AhPEPC1, AhPEPC2, AhPEPC3, and AhPEPC4) was relatively high in roots, while the bacterial type PEPC (BTPC) (AhPEPC5) showed a remarkable expression level in flowers. Principal component analysis (PCA) result showed that AhPEPC3 and AhPEPC4 are correlated with each other, indicating comparatively associations with roots, and AhPEPC5 have a very close relationship with flowers. In order to investigate the function of these AhPEPCs, the fragments of these five AhPEPC cDNA were cloned and expressed in Escherichia coli (E. coli). The recombinant proteins contained a conserved domain with a histidine site, which is important for enzyme catalysis. Results showed that protein fragments of AhPEPC1, AhPEPC2, and AhPEPC5 had remarkable expression levels in E. coli. These three recombinant strains were more sensitive at pH 9.0, and recombinant strains carrying AhPEPC2 and AhPEPC5 fragments exhibited more growth than the control strain with the presence of PEG6000. Our findings showed that the expression of the AhPEPC fragments may enhance the resistance of transformed E. coli to osmotic stress.

As the energy center of the cell, mitochondria display enormous metabolic plasticity to meet the cellular demand for plant growth and development, which is tightly linked to their structural and dynamic plasticity. Mitochondrial number and morphology are coordinated through the actions of the mitochondrial division and fusion. Meanwhile, damaged mitochondrial contents are removed to avoid excess toxicity to the plant cells. Mitophagy, a selective degradation pathway of mitochondria through a double-membrane sac named autophagosome (also known as mitophagosome), plays a crucial role in maintaining mitochondrial homeostasis. Typically, wholesale mitophagy requires the elongation of a cup-shaped phagophore along the entire mitochondrion, which finally seals and closes as a mitophagosome. How plant mitophagosome formation and mitochondria sequestration are coordinated remains incompletely understood. In this work, we report an unappreciated role of the plant-specific mitochondrial fission regulator ELM1, together with the dynamin-related protein family DRP3 and the autophagic regulator SH3P2, to coordinate mitochondria segregation for piecemeal mitophagy under heat stress conditions. Dysfunction in mitochondrial fission activity impairs heat-induced mitophagy, leading to an accumulation of interconnected megamitochondria which are partially sequestered by the ATG8-positive phagophore. Furthermore, we show that the ELM1-mediated piecemeal mitophagy also engages the plant archetypal selective autophagic receptor NBR1. Using 3D tomography analysis, we illustrate the morphological features and spatial relationship of the megamitochondria and phagophore intermediates in connection with the mitochondrial fission sites. Collectively, our study provides an updated model of mitophagosome formation for piecemeal mitophagy mediated by the plant-unique mitochondrial fission machinery.

Mulberry is a plant species of significant economic value and is widely incorporated into various traditional medicinal formulations. Its multiple botanical parts (leaves, branches, fruits, seeds, and roots) possess both nutritional and therapeutic properties. Throughout its growth cycle, mulberry is exposed to a range of abiotic and biotic stresses. In response, the plant has evolved a suite of stress tolerance mechanisms, notably including the synthesis of diverse secondary metabolites. These metabolites, which encompass phenolic acids, flavonoids, and volatile aromatic compounds, exhibit pronounced pharmacological activities. This review systematically elucidates the roles of mulberry-derived phenolic compounds, alkaloids, and polysaccharides, which demonstrate a broad spectrum of biological effects, including antioxidant, antibacterial, antiviral, anticancer, anti-inflammatory, neuroprotective, anti-obesity, antidiabetic, and anti-enteritis activities. By integrating knowledge of mulberry’s adaptive mechanisms to abiotic and biotic stresses with the therapeutic functions of its extracts, this review aims to provide novel insights to guide future molecular breeding strategies and drug development efforts.