This article describes the main features of plant stem cells and summarizes the results of studies of the genetic control of stem cell maintenance in the apical meristem of the shoot. Paracrine brassinosteroid signaling at the stem cell niche. Hormonal regulation of stem cell maintenance in roots. During embryonic development, various niche factors act on embryonic stem cells to. A root is formed from a reservoir of undifferentiated cells, called root stem cells, in the root apical meristem ram. Plant tissue culture and subsequent organogenesis have been regarded as part of the scientific roots of modern plant biotechnology sussex, 2008. In root meristems, individual stem cells are controlled by direct interaction. Jun 24, 2010 hormonal control of the shoot stem cell niche. Morphology of the shoot apical meristem sam and floral meristems fm. Direct conversion of root primordium into shoot meristem relies on. Hormonal control of the shoot stem cell niche core.
A regulatory framework for shoot stem cell control integrating. A stem cell niche is the area where stem cell division and renewal is maintained through signals from neighboring organizing center oc aichinger et al. Shoot apical meristems sams harbor a set of stem cells which supply cells for the development of all aboveground structures. Pdf hormonal regulation of stem cell maintenance in roots. In the shoot apical meristem, auxin accumulates in both stem cells in the central zone and differentiated cells in the periphery zone. Accordingly, the niche is able to withstand the hormonal shock and continues to provide cells to sustain organ growth, root or shoot, whereas a precocious cytokinin treatment results in the terminal differentiation of cells in the bulging primordium in the absence of a stem cell niche. Jan lohmann department of stem cell biology heidelberg institute of zoology university of heidelberg d 69120 heidelberg, germany ph. Postembryonic control of root meristem growth and development. The shoot stem cells are located in the tip of the shoot and share the similar developmental pattern to root stem cells. Here, we dissect how light and metabolic signals are integrated to overcome stem cell dormancy at the shoot apical meristem. Although cells of the qc have a very low mitotic activity, plant hormones such as. Establishments of shoot apical meristem sam and root apical meristem ram are critical steps for somatic embryogenesis scheres et al. Abstract plant hormones regulate many aspects of plant growth and development. A molecular framework for auxincontrolled homeostasis of.
Hormones control every stage of stem cell life, including establishment, expansion, maintenance, and differentiation. At least nine groups of plant hormones have been studied extensively. In arabidopsis roots, a reduced group of cells known as the quiescent center qc act as a cell reservoir for surrounding stem cells during both normal growth and in response to external damage. Jun 24, 2010 our results provide a mechanistic framework for hormonal control of the apical stem cell niche and demonstrate how root and shoot stem cell systems differ in their response to phytohormones. This process was strongly inhibited by the elimination of cauline leaves, shoot apices, or lateral. Genetic regulation of plant shoot stem cells springerlink.
These findings elucidate a regulatory framework for flower primoridium initiation by auxin and coordination with flower morphogenesis. Sep 20, 2011 when grafting or wounding disconnects stem tissues, new tissues are generated to restore the lost connection. Stem cell niche refers to a microenvironment, within the specific anatomic location where stem cells are found, which interacts with stem cells to regulate cell fate. In this study, the molecular mechanism of such healing was elucidated in injured stems of arabidopsis. Using computational and experimental approaches, we have tested and found support for a hypothesis for gene interactions that specify the arabidopsis apical stem cell population. This book describes recent advances in our understanding of pluripotency and the hormonal regulation of embryonic stem cell differentiation into tissue types derived from the ectoderm, mesoderm and endoderm. Short hypocotyl under blue1 associates with miniseed3 and haiku2 promoters in vivo to regulate arabidopsis seed development.
Our results provide a mechanistic framework for hormonal control of the apical stem cell niche and demonstrate how root and shoot stem cell systems differ in their response to phytohormones. The stem cell niche provides a microenvironment composed of cellular structures or extracellular matrix in which stem cells are maintained as undifferentiated 16. Stem cell fate in the shoot apical meristem sam is controlled by the homeodomain transcription factor wuschel wus expressed in the niche adjacent to the stem cells. Soon after the inflorescence stems were incised, the pith cells started to divide. A molecular framework for the embryonic initiation of. These stem cells in shoot and root apical meristems remain as pluripotent state throughout the lifespan of the plant and control the growth and. Hollow xylem cells reinforced with thick secondary cell walls provide mechanical strength to the stem and a means of rootto shoot transport. Moreover, a single hormone can affect different stem cells in different ways or affect the same stem cell differently at various developmental times. When the shoot stem cells divide, some daughter cells remain stem cell state in a small restrained region to keep selfrenewal, while the other daughter cells will become incorporated into all the. This elegant strategy can be applied to the field of roots to dissect molecularly the effect of hormonal crosstalk on the regulation of root stem cell activity at the transcriptional level since the fluorescenceactivated cell sorting method is now widely available for the analysis of cell typespecific responses in plants nawy etal.
Hormonal control of the shoot stemcell niche nature. Integration of light and metabolic signals for stem cell. Auxin is synthesized at the shoot tip and is transported down to the qc. However, the presence of a stem cell niche is not always. Towards a functional understanding of cell growth dynamics in. Their spatial arrangement might position the new shoot stem cell niche and guide. All living plant cells can be triggered to dedifferentiate, assume different cell identities, or form a new organism. Recent discoveries have advanced our understanding of the orchestration of plant. Wuschel wus, a homeodomain protein, controls stem cell differentiation and maintenance and its. Hormonal regulation of stem cell maintenance in roots pdf. Jun 02, 2017 hormonal control of the shoot stemcell niche.
Plant hormones control root growth and development by balancing between cell division and differentiation, and their interactions are crucial for the temporal and spatial coordination of root development. Oct 23, 2017 similarly to the shoot stem cell system, the balance between auxin and cytokinin is essential to control the dynamics of stem cell differentiation at the root apical meristem di mambro et al. Plant stem cell niches the international journal of developmental. Initiation and maintenance of plant stem cells in root and. Maintenance of the stem cell niche is the basis for formation of proper ram morphology, which is controlled by several hormonal pathways lee et al. Among these, the hormone auxin signals through the auxin inducible plethora plt14 transcription factors. Molecular mechanism of crown root initiation and the. A crucial role in regulating the fate of daughter cells and proliferative activity of stem cells is played by the cellular and noncellular vicinity of stem cells, the socalled niche. Control of plant cell fate transitions by transcriptional and. Hormonal control of the shoot stemcell niche article pdf available in nature 4657301.
Pluripotency is a prerequisite for the subsequent coordinated differentiation of embryonic stem cells into all tissues of the body. It is demonstrated that the wusclv gene system plays a key role in the maintenance of shoot apical stem cells and the formation of adventitious buds and somatic embryos. Control of root stem cells by plant hormones and their crosstalks. The effects can be cell autonomous or noncell autonomous through the niche. The control of the location and activity of stem cells depends on spatial regulation of gene activities in the stem cell niche. Here we show a direct role of mpdrnmediated auxin signaling in regulation of the stem cell pool by interfering with the wusclv3 feedback loop, and provide a mechanistic framework for auxin control of stem cell homeostasis by balancing maintenance and. In shoot meristems, stem cell fate is decided at the populational level. Pdf the classic phytohormones cytokinin and auxin play essential roles in the maintenance of stemcell systems embedded in shoot and root meristems. Frontiers the essential role of cytokinin signaling in root. Oct 06, 20 hormonal control of stem cell systems such changes may originate from tissuespecific stem cells and their supportive environment niche. In the meristematic zone, there is a stem cell niche scn that.
Our results provide a mechanistic framework for hormonal control of the apical stemcell niche and demonstrate how root and shoot stemcell systems differ in their response to phytohormones. Root stem cell specification and maintenance is the result of convergent phytohormone, transcription factor, and peptide signaling pathways. The endocrine system is a major effector and conveyor of physiological changes and as such could alter stem cell behavior in various ways. This developmental plasticity is thought to be an adaptation to the sessile lifestyle of plants. Hence, tight control of cell fate decisions among stem cell derivatives can be expected. Typeb arabidopsis response regulators specify the shoot stem cell niche by dual regulation of wuschelopen wen jing meng,1 zhi juan cheng,1 ya lin sang,1 miao miao zhang, xiao fei rong, zhi wei wang, ying ying tang. Environmental and hormonal control of cambial stem cell. Control of stemcell niche establishment in arabidopsis flowers by revoluta. The genetic control of in vitro plant regeneration occurs at multiple levels of regulation. Stem cell regeneration is crucial for both cell turnover and tissue healing in multicellular organisms. Body regeneration through formation of new organs is a major question in developmental biology. Typeb arabidopsis response regulators specify the shoot stem. Recent studies of the regulators of the sam and fm have revealed that plant hormones contribute to the finetuning of meristem mainte nance and organ formation. Information integration and communication in plant.
A precise spatiotemporal control of growth patterns in stem cells and the differentiating progeny is critical to maintain a stable set of stem cells. Stem cell activation by light guides plant organogenesis. The roles of plant hormones and their interactions with. The word niche can be in reference to the in vivo or in vitro stem cell microenvironment. Pdf hormonal control of the shoot stemcell niche researchgate. Zhao z1, andersen su, ljung k, dolezal k, miotk a, schultheiss sj, lohmann ju. Jul 11, 2016 a major feature of embryogenesis is the specification of stem cell systems, but in contrast to the situation in most animals, plant stem cells remain quiescent until the postembryonic phase of development.
Initiation and maintenance of plant stem cells in root and shoot. Pattern of auxin and cytokinin responses for shoot meristem. However, when ethanol induction was started after the specification of shoot stem cell niche at sim8 or the establishment of the shoot meristem at sim12, the percentages of shoot regeneration at sim8 77. Our results show that local cytokinin biosynthesis and auxin biosynthesis in the leaf blade followed by auxin longdistance transport to the petiole leads to proliferation of j0121marked xylem.
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