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ABSTRACT Mineral nutrients are essential for plant growth, development and crop yield. Under mineral deficient conditions, plants rely on a sophisticated network of signalling pathways to coordinate their molecular, physiological, and morphological responses. Recent research has shown that long‐distance signalling pathways play a pivotal role in maintaining mineral homeostasis and optimising growth. This review explores the intricate mechanisms of long‐distance signalling under mineral deficiencies, emphasising its importance as a communication network between roots and shoots. Through the vascular tissues, plants transport an array of signalling molecules, including phytohormones, small RNAs, proteins, small peptides, and mobile mRNAs, to mediate systemic responses. Vascular tissues, particularly companion cells, are critical hubs for sensing and relaying mineral deficiency signals, leading to rapid changes in mineral uptake and optimised root morphology. We highlight the roles of key signalling molecules in regulating mineral acquisition and stress adaptation. Advances in molecular tools, including TRAP‐Seq, heterografting, and single‐cell RNA sequencing, have recently unveiled novel aspects of long‐distance signalling and its regulatory components. These insights underscore the essential role of vascular‐mediated communication in enabling plants to navigate heterogeneous mineral distribution environments and suggest new avenues for improving crop resilience and mineral use efficiency. 

The life cycle of land plants is characterized by alternating generations of sexual gametophytes and asexual sporophytes. Unlike seed plants, seed-free vascular plants, including ferns, initiate and maintain pluripotent meristems during their gametophyte phase to sustain body expansion and drive the formation of sexual organs for reproduction. This review summarizes meristem development among various fern species during the gametophyte phase, focusing on the cellular basis of meristem initiation, proliferation, and termination. We review the different types of gametophytic meristems in ferns, including apical cell (AC)-based meristems, multicellular apical meristems, and multicellular marginal meristems. We highlight both conserved and lineage-specific patterns of cell division, which are closely associated with these meristem identities and play crucial roles in shaping gametophytic morphology. Additionally, we highlight recent progress in understanding the dynamics of cell division and growth that drive meristem development, through studies that integrate confocal live imaging and computational quantitative analysis. Furthermore, we discuss the influence of environmental and genetic factors on cell division activity in fern gametophytes, including conserved transcriptional regulators that sustain meristem indeterminacy and proliferation in the model fern Ceratopteris richardii. 

ABSTRACT A fascinating feature of land plants is their ability to continually initiate new tissues and organs throughout their lifespan, driven by a pool of pluripotent stem cells located in meristems. In seed plants, various types of meristems are initiated and maintained during the sporophyte generation, while their gametophytes lack meristems and rely on sporophyte tissues for growth. In contrast, seed‐free vascular plants, such as ferns, develop meristems during both the sporophyte and gametophyte generations, allowing for the independent growth of both generations. Recent findings have highlighted both conserved and lineage‐specific roles of the HAIRY MERISTEM (HAM) family of GRAS‐domain transcriptional regulators in various meristems throughout the land plant lifecycle. Here, we review and discuss howHAMgenes maintain meristem indeterminacy in both sporophytes and gametophytes, with a focus on studies performed in two model species: the flowering plantArabidopsis thalianaand the fernCeratopteris richardii. Additionally, we summarize the crucial and tightly regulated functions of the microRNA171 (miR171)‐HAM regulatory modules, which define HAM spatial patterns and activities during meristem development across various meristem identities in land plants.