Cell wall degradation and the dynamic changes of Ca²⁺and related enzymes in the developing aerenchyma of wheat (Triticum aestivumL.) under waterlogging

Abstract

This research was aimed to study the cell wall degradation and the dynamic changes of Ca2+ and related enzymes in developing aerenchyma of wheat root under waterlogging. An examination of morphological development by light and electron microscope revealed that the structure of cell wall in middle cortical cells remained intact after 12 h of waterlogging and turned thinner after waterlogging for 24 h. At 48 h, the aerenchyma has been formed. The cellulase activity gradually increased in middle cortical cells within 24 h of waterlogging, and decreased with the formation of aerenchyma. Fluorescence detection and subcellular localization of Ca2+ showed the dynamic changing of Ca2+ at the cellular and subcellular levels during the development of aerenchyma. The activity of Ca2+-ATPase enhanced markedly in intercellular space, plasma membrane and tonoplast of some middle cortical cells after 8 h of waterlogging and remained high after 24 h, but it decreased after 48 h of waterlogging. All these suggests that cellulase, Ca2+ and Ca2+-ATPase show a dynamic distribution during the aerenchyma development which associated with the cell wall degradation of middle cortical cells. Moreover, there is a feedback regulation between Ca2+ and Ca2+-ATPase.

Ethylene-Mediated Acclimations to Flooding Stress

“…These start with plasma membrane invagination and vesicle formation followed by nuclear events, such as chromatin condensation and DNA fragmentation, and ultimately, cell wall breakdown and collapse of the entire cell, leaving behind empty air spaces. Cell wall degradation involves ethylene-mediated increases in activities of enzymes, such as cellulases, pectinases, and xylanases (Bragina et al, 2003;Xu et al, 2013).…”

Calcium-Mediated Abiotic Stress Signaling in Roots

“…Oxygen deprivation (and also sulfur and phosphate, Pi, deprivation) triggers programmed cell death (PCD) in mid-cortical cells for aerenchyma formation (Fagerstedt, 2010). This PCD is stimulated by ethylene and ROS and involves Ca 2+ (Xu et al, 2013; Petrov et al, 2015). In wheat roots, anoxia causes mitochondria to release their Ca 2+ and high [Ca 2+ ] cyt causes cytochrome c release (Virolainen et al, 2002).…”

Potential Role of Plant Growth Regulators in Administering Crucial Processes Against Abiotic Stresses

“…However, the ultimate direction of root extension in the direction of moist areas of the soil is primarily controlled by ABA signaling, which can be overwhelmed by the auxins mediated gravitropism (Taniguchi et al, 2010). Xu Q. T. et al (2013) inferred that the ABA regulates primary root and root hair growth by mediating the auxin passage in both Arabidopsis thaliana and Oryza sativa plants. Furthermore, it causes an increase in the proton secretion process by the accomplishment of plasma membrane-bounded H-ATPases and maintains root elongation.…”

“…Plant roots grown in highly acidic soils exhibit vast transcriptional modifications in the expression of some auxin-related genes, implying auxin-mediated alterations on root architecture (Lager et al, 2010). The PIN2 maintained buffering of extreme soils was observed in roots of plants growing in alkaline conditions where auxin transport activity is mediated by PIN2 followed by auxin-mediated activation of plasma membrane H + -ATPase and photon emission in the root tips (Xu Q. T. et al, 2013). Auxin biosynthesis and transportation in response to specific salt stress should be further studied to understand the underlying mechanism of auxin modulation.…”