Molecular mechanisms of natural de novo shoot organogenesis and their applications.

Variable NAA concentrations regulate efficient somatic embryogenesis and plant regeneration mediated by FELBs and RTBs in Allium fistulosum.

Somatic embryogenesis (SE) underpins plant regeneration, genetic transformation and virus-free seedling propagation, yet efficient SE systems using root explants remain lacking in Allium fistulosum. Here, we establish and characterize two novel high-efficiency SE pathways mediated by frog egg-like bodies (FELBs) and rhizoid tubers (RTBs) in A. fistulosum, and clarify the regulatory effects of NAA, 2,4-D and TDZ on morphogenesis and plant regeneration. Screening of multiple explants demonstrated that only root segments and stem tips could form translucent mucilaginous callus, while single 2,4-D treatment failed to induce callus at all tested concentrations. Under dark conditions, 10 mg/L NAA maximized callus induction (94.233%) and FELB formation (87.833%) in root explants with significant dose-dependent effects. Phytocytohistological analysis confirmed that FELBs/RTBs develop via three unique stages (pro-embryo, globular embryo, heart/torpedo transitional embryo), distinct from the five canonical stages of typical somatic embryos. For RTB pathway, 5.0 mg/L NAA induced the maximum rhizoid number (54.867 per explant), and subsequent treatment with 20.0 mg/L TDZ under high light achieved optimal RTB production (51.333 per explant). Stage-specific BAP application yielded 100% FELB germination and over 90% RTB plantlet regeneration, with both regenerated seedlings exhibiting > 90% acclimatization survival rates. This study first elucidates the ontogeny of FELB and RTB in monocot A. fistulosum. This is the first study characterizing FELB/RTB developmental stages and ontogeny in a monocot, showing striking homology to eudicotyledons, confirming that FELB- and RTB-mediated somatic embryogenesis can also be achieved in monocots. These optimized systems provide robust technical support for high-frequency regeneration, genetic modification and virus-free seedling production of Allium crops.

miR319 promotes de novo shoot regeneration by repressing LsTCP4 in lettuce

Plant regeneration is a major determinant of transformation and genome-editing efficiency, yet the endogenous regulatory networks controlling regenerative competence in horticultural crops remain incompletely understood. The miR319–TCP module regulates multiple developmental processes in plants, but its function in lettuce regeneration has not been defined. Here, we performed a genome-wide analysis of the TEOSINTE BRANCHED1/CYCLOIDEA/PROLIFERATING CELL FACTOR (TCP) gene family in lettuce (Lactuca sativa). Thirty-three LsTCP genes were identified and classified into Class I/PCF, Class II/CIN, and Class II/CYC/TB1 groups. Five CIN-class genes, LsTCP2, LsTCP3, LsTCP4, LsTCP10, and LsTCP24, were predicted as high-confidence miR319 targets and supported by degradome-based cleavage evidence. MIR319-overexpression (OX319) explants showed enhanced de novo shoot regeneration, with 94.5% regeneration efficiency and 1.92 shoots per explant, whereas STTM-miR319 suppression (S319) explants showed reduced regeneration, with 28.5% regeneration efficiency and 0.36 shoots per explant. These phenotypes were associated with altered expression of several miR319-targeted CIN-TCP genes, particularly LsTCP4, LsTCP10, and LsTCP24. Disruption of LsTCP4 increased regeneration efficiency to 91.4% and shoot production to 2.05 shoots per explant, resembling the regeneration-enhancing effect of miR319 overexpression. In contrast, disruption of the non-target CIN gene LsTCP17 did not significantly affect regeneration under the tested conditions. Together, these results identify LsTCP4 as a key miR319-responsive negative regulator of de novo shoot regeneration and highlight miR319-mediated repression of LsTCP4 as a potential endogenous strategy for improving lettuce regeneration.

Integrated analysis of ROS, hormone signaling and transcriptional networks reveals candidate regulatory programs associated with hormone-free callus formation in kiwifruit

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.

Specification of embryonic shoot stem cells via a small RNA-driven morphogenic circuit

The small RNA tasiARF initiates a self-reinforcing morphogenic circuit connecting cell wall mechanics, auxin signaling, and regulated cell division to specify embryonic shoot stem cell fate, revealing how lineage-specific regulatory innovation can preserve a conserved developmental output across divergent embryonic architectures.

Spatial Transcriptomics in Plants: From Cellular Maps to Mechanistic Insight.

This review synthesizes recent progress across diverse plant species and tissues, showing that gene expression is not only cell-type specific but also tightly organized by position within organs and developmental niches, establishing spatial gene expression as a fundamental organizing principle of plant development and physiology.