Emerging Roles of Polyamines and Autophagy in Plant In Vitro Regeneration

ATG5 Engineers Stem Cell Plasticity to Regulate Functional Fitness During Development and Disease

Autophagy, an evolutionarily conserved and tightly controlled process in eukaryotic cells, allows them to respond to stress by selectively eliminating dysfunctional or unwanted materials to promote metabolic flexibility and maintain homeostasis. While autophagy is orchestrated by different autophagy (ATG)-related genes, whose regulation varies considerably according to tissue type and developmental stage. In this review, we investigate how regardless of the different players involved in autophagy, ATG5 emerges as a unique, highly conserved, critical molecule that acts as a central rheostat to control the stem cell fate, metabolic adaptability, and govern the immune signature pattern in cells. The journey of ATG5 modulation from physiological developmental variation to pathological scenario brings out the translational impact of ATG5. On the one hand, ATG5 promotes exit from the pluripotent state by c-Myc degradation during differentiation of specific lineages (involved in neurogenesis, adipogenesis, and hematopoiesis), while on the other hand, it has a critical involvement in metabolic circuitry via rewiring autophagy through modulation of lipophagy, mitophagy, and acetyl-CoA epigenetics. Taken together, this work summarizes new findings that centrally place ATG5 as a driver that engineers a coordinated crosstalk between the metabolic state and cell fate decisions and immune responses. These insights position ATG5 as a critical and therapeutic target for developmental disorders, cancer, and immune-metabolic diseases. Graphical Abstract This is a visual representation of the abstract.

Emerging insights into developmental programmed cell death in plants.

This review provides an integrative overview of developmental PCD across vegetative and generative stages, from reproductive development and embryogenesis to vascular differentiation, aerenchyma formation, organ shaping, senescence, and abscission, and summarizes current knowledge of the molecular, cellular, and physiological mechanisms governing dPCD.

The multifaceted role of gibberellins in somatic embryogenesis: from in vitro culture to molecular networks

Gibberellins (GAs) are central regulators of plant growth and development, yet their involvement in somatic embryogenesis (SE) has received limited attention and often produces contradictory results. This review critically examines the current knowledge on the role of GAs in SE by integrating evidence from physiological, molecular, and developmental studies across a wide range of plant species. Available data indicate that exogenous GAs and GA biosynthesis inhibitors can either promote or inhibit the induction, progression, and conversion of somatic embryos, depending on the species, genotype, explant origin, developmental stage, and culture conditions. These opposing effects underscore that exogenous responses are tightly linked to endogenous GA homeostasis. Particular attention is paid to GA metabolism and signaling genes, whose expression patterns during SE reveal substantial interspecific and genotypic variation. Endogenous GA profiles reveal that both high and low levels of bioactive GAs correlate with SE induction across different systems, suggesting that endogenous GA levels may be a key determinant of embryogenic competence and may underlie major differences in regeneration capacity among species and genotypes. Furthermore, GAs function within a broader regulatory network through extensive crosstalk with other hormones (auxins, abscisic acid, cytokinins, and ethylene), environmental factors (e.g., light and temperature) and interactions with major embryogenesis-related transcription factors such as LEC1, LEC2, FUS3, ABI3, AGL15, AGL18, and BBM. These interactions position GAs as dynamic components of a multilayered hormonal and transcriptional framework that controls the switch from somatic to embryogenic development. Integrative approaches—including hormone profiling, gene expression analysis, functional genetics, and developmental studies—are essential to elucidate the precise function of GAs in SE and thereby improve protocols for plant regeneration.

Organ identity shapes autophagy dynamics and selectivity in plants

Physiology and Biochemistry of Flower Senescence: Mechanisms, Regulation and Implications for Postharvest Longevity

Flower senescence represents a genetically programmed and tightly regulated terminal phase of floral development that plays a critical role in reproductive success and postharvest performance of ornamental and horticultural crops. This review provides a comprehensive synthesis of the physiological and biochemical processes governing flower senescence, with emphasis on hormonal control, metabolic alterations and cellular signaling mechanisms. Ethylene acts as a primary regulator in many species by inducing senescence associated gene expression, whereas ethylene independent pathways also contribute to senescence regulation, reflecting species specific variability. Key physiological changes include deterioration of membrane integrity, disruption of water relations, reduced respiratory efficiency and loss of cellular homeostasis. Biochemically, senescence is marked by enhanced generation of reactive oxygen species, lipid peroxidation, degradation of proteins and nucleic acids and coordinated modulation of antioxidant defence systems. Alterations in carbohydrate metabolism, sugar signaling and secondary metabolites further influence the progression of senescence. The review has also highlighted the roles of calcium signaling, polyamines, nitric oxide and programmed cell death in regulating senescence responses. Understanding of these integrated physiological and biochemical mechanisms is essential for developing effective strategies to extend floral longevity and improve postharvest quality.

Metabolic control of cellular reprogramming: phospholipid remodeling tunes auxin signaling

Plant cells possess remarkable developmental plasticity and can regain their proliferative capacity through cellular reprogramming to form pluripotent cell masses known as callus, which serves as the foundation for plant regeneration and tissue culture. Induction of callus formation begins with explants on auxin-rich callus-inducing medium (CIM), a process tightly controlled by auxin signaling. The canonical IAA14– ARF7/19 signaling module and its downstream targets, including LATERAL ORGAN BOUNDARIES DOMAIN (LBD) transcription factors and WRKY23, are indispensable for callus formation and the establishment of cellular pluripotency (Xu et al. 2023). Lipids are fundamental components of plant membranes that maintain membrane integrity, dynamics, and energy storage.