Trends in Plant Science
ForumDetermining Cellular Responses: Phytoglobins May Direct the Traffic
Section snippets
Plant Cell Fate Determination
Plant tissues comprise cells that have acquired a diverse fate depending on internal or external stimuli. However, the ontogeny of these cells can be traced back to a limited number of stem cells, which, by retaining an undifferentiated and uncommitted state, generate derivatives that embark on different differentiation processes. Mechanisms by which stem cells acquire and maintain their state and factors triggering cell-specific differentiation processes remain unknown and constitute a
NO as a Key Component in Regulating Cellular Processes
NO generation is associated with hormonal responses 2, 6 and actions that result in, or are a consequence of, the production of reactive oxygen species (ROS) or reactive nitrogen species [4] (Figure 1). NO has been implicated in environmental stress responses 2, 7, such as its effect on ethylene formation in the hyponastic response accompanying plant submergence [8] and during root hypoxic responses [3]. Furthermore, ethylene response factors (ERFs) are determinants in the avoidance or escape
Phytoglobin Action in the Cell
One of the predominant features of plant environmental stress is increased cellular production of ROS [4] (Figure 1). This generally occurs as a result of disruption of mitochondrial processes leading to increased cytoplasmic NO production, via reactions occurring in the electron transport chain or elsewhere in the cell, and the induction of NADPH oxidases. The action of phytoglobin in removing NO both downregulates NADPH oxidase gene expression 3, 5, 10 and promotes expression of genes
Evidence for Cell-Specific Expression of Phytoglobins
A typical consequence of ROS production in the cell, as a result of environmental stress or plant development, is the induction of PCD [3]. Three to five types of phytoglobin genes encode the protein. Because of this diversity, there is the potential to direct gene expression to specific sets of cells in accordance with the perturbation initiating the process. Evidence of cell-specific phytoglobin expression associated with PCD has been found with hypoxic stress 10, 11 (Figure 2A) and with the
Concluding Remarks
Factors influencing cell fate and differentiation, the external morphology of organs and organisms based on selective PCD, and the response of cells to their external environment are fundamental topics in plant biology. The ideas described here provide one thread to pull that may unravel the process by which these events are controlled in often specific plant domains. The distinctive, simple chemical action of phytoglobin would seem to provide an uncomplicated means of regulating plant cellular
References (12)
Learning to breathe: developmental phase transitions in oxygen status
Trends Plant Sci.
(2017)Function of the type-2 Arabidopsis hemoglobin in the auxin-mediated formation of embryogenic cells during morphogenesis
Plant J.
(2013)Non-symbiotic haemoglobins – what’s happening beyond nitric oxide scavenging?
AoB Plants
(2012)Regulation of programmed cell death by phytoglobins
J. Exp. Bot.
(2016)Hemoglobin control of cell survival/death decision regulates in vitro plant embryogenesis
Plant Physiol.
(2014)Nitric oxide (NO) and phytohormones crosstalk during early plant development
J. Exp. Bot.
(2015)
Cited by (8)
Spatial identification of transcripts and biological processes in laser micro-dissected sub-regions of waterlogged corn roots with altered expression of phytoglobin
2019, Plant Physiology and BiochemistryCitation Excerpt :There was no indication of major changes in Pgb gene expression in these cells. Since the suppression of genes required for the production of ROS is associated with Pgb expression (Stasolla and Hill, 2017; Mira et al., 2016b), one would anticipate a lack of involvement of Pgb in ROS-associated programmed cell death in cortical cells during lysogenous aerenchyma formation. Considering the evidence that Pgbs have a positive influence on tolerance to hypoxia and that their expression is cell-specific (Mira et al., 2016b, 2017), comparative transcriptional analyses were conducted using laser micro-dissection of waterlogged WT plants and plants over-expressing ZmPgb1.2 to assess how Pgb influenced cell-specific gene expression during hypoxia in root tip sub-regions.
In vitro differentiation of tracheary elements is induced by suppression of Arabidopsis phytoglobins
2019, Plant Physiology and BiochemistryCitation Excerpt :It is speculated that this model, in which Pgbs act as inhibitors of cell differentiation, might also operate in vivo systems. Phytoglobins are in fact present in meristematic (undifferentiated) domains (Stasolla and Hill, 2017) and their suppression triggers morphological changes typical of differentiation and PCD (Mira et al., 2017a). Thus, besides their well-established involvement in stress responses, Pgbs likely govern broader aspects of growth and development involving cell fate acquisition.
Plant hemoglobins: a journey from unicellular green algae to vascular plants
2020, New PhytologistStem cell fate in hypoxic root apical meristems is influenced by phytoglobin expression
2020, Journal of Experimental BotanySpatio-temporal expression of phytoglobin: A determining factor in the NO specification of cell fate
2019, Journal of Experimental BotanyRedirecting Cell Fate During in vitro Embryogenesis: Phytoglobins as Molecular Switches
2018, Frontiers in Plant Science