Expression of Arabidopsis class 1 phytoglobin (AtPgb1) delays death and degradation of the root apical meristem during severe PEG-induced water deficit

Abstract

Retardation of growth induced by water stress is attenuated by the overexpression of AtPgb1 and aggravated when it is suppressed. Expression of AtPgb1 is required to delay the death of root tips and to prevent the premature differentiation of meristematic cells.

Biology in the Dry Seed: Transcriptome Changes Associated with Dry Seed Dormancy and Dormancy Loss in the Arabidopsis GA-Insensitive sleepy1-2 Mutant

“…For example, the AHb1 transcript was not AR-up-regulated in Cvi, but was strongly AR-up-regulated transcript in dry seeds of sly1-2 and L er . AHb1 (also called Arabidopsis class 1 phytoglobin or pgb1 ) protects roots from severe oxidative stress ( Hill et al, 2016 ; Mira et al, 2017 ). Thus, it may play a similar role in dry seeds.…”

Redirecting Cell Fate During in vitro Embryogenesis: Phytoglobins as Molecular Switches

“…These events can be replicated by targeting Pgb2 in the cytoplasm (Godee et al, 2017 ). A further elaboration of this model, reinforcing the link between Pgb and stress response factors in the somatic-embryogenic transition includes the suppression of MYC2 by jasmonic acid (JA) in cells enriched in NO as a result of Pgb2 suppression (Mira et al, 2017 ). A fundamental concept emerging from these studies is that the level of Pgbs in the cells is a determining factor in the redirection of the fate of a somatic cell toward an embryogenic pathway; this redirection seems to employ components shared in stress responses.…”

Protection of root apex meristem during stress responses

“…As NO scavengers, Pgbs have the capacity to interrupt the action of NO and manage plant developmental and stress responses in which NO is a component of the signal transduction pathway orchestrating hormone responses and PCD. 4,5,19,20,21,22 More importantly, the expression of Pgbs can be cell-specific, allowing cells adjacent to one another to respond differently to a given perturbation.…”

“…3 If the dismantling and elimination of specific cells by death is needed for the well-being of the organism, survival is ultimately dependent on the ability of plants to ensure that sensitive, meristematic regions do not succumb to the stress. For example, the prevention of death in root meristematic cells ensures root growth and enhances plant performance under conditions of limited 4 and excessive 5,6 moisture. Furthermore, cells destined to die are often in close proximity to those that need to remain viable, as shown in corn where PCD-targeted cells forming aerenchyma are separated by only a few layers of cells from the apical meristem.…”

“…8 It has been suggested that Pgbs might act as universal molecular switches governing cell fate through NO. 9 A recent paper 4 provides evidence to suggest that the expression of Pgb during environmental stress may have a profound influence on how meristematic regions respond to the stress.…”