Different Modes of Hydrogen Peroxide Action During Seed Germination

Abstract

Hydrogen peroxide was initially recognized as a toxic molecule that causes damage at different levels of cell organization and thus losses in cell viability. From the 1990s, the role of hydrogen peroxide as a signaling molecule in plants has also been discussed. The beneficial role of H2O2 as a central hub integrating signaling network in response to biotic and abiotic stress and during developmental processes is now well established. Seed germination is the most pivotal phase of the plant life cycle, affecting plant growth and productivity. The function of hydrogen peroxide in seed germination and seed aging has been illustrated in numerous studies; however, the exact role of this molecule remains unknown. This review evaluates evidence that shows that H2O2 functions as a signaling molecule in seed physiology in accordance with the known biology and biochemistry of H2O2. The importance of crosstalk between hydrogen peroxide and a number of signaling molecules, including plant phytohormones such as abscisic acid, gibberellins, and ethylene, and reactive molecules such as nitric oxide and hydrogen sulfide acting on cell communication and signaling during seed germination, is highlighted. The current study also focuses on the detrimental effects of H2O2 on seed biology, i.e., seed aging that leads to a loss of germination efficiency. The dual nature of hydrogen peroxide as a toxic molecule on one hand and as a signal molecule on the other is made possible through the precise spatial and temporal control of its production and degradation. Levels of hydrogen peroxide in germinating seeds and young seedlings can be modulated via pre-sowing seed priming/conditioning. This rather simple method is shown to be a valuable tool for improving seed quality and for enhancing seed stress tolerance during post-priming germination. In this review, we outline how seed priming/conditioning affects the integrative role of hydrogen peroxide in seed germination and aging.

Free Radicals and Antioxidant System in Seed Biology

“…In plant cells, ascorbate peroxidase (APX) and catalase (CAT) that are involved in scavenging H 2 O 2 are localized at the site of H 2 O 2 generation [93] (Figure 2). H 2 O 2 is mentioned to induce expression of many genes, coding defense-related proteins, transcription factors, phosphatases, kinases and enzymes involving in ROS synthesis or degradation [37,54,56,79,80] (Figure 2).…”

“…Cellular antioxidant mechanisms control ROS concentrations, rather than to eliminate them completely, suggesting that some ROS may act as signaling molecules [5,[34][35][36][37]46]. Although ROS have been considered as detrimental to seeds, advances in plant physiology evaluated them as messengers of various signal transduction pathways in plants.…”

“…Although ROS have been considered as detrimental to seeds, advances in plant physiology evaluated them as messengers of various signal transduction pathways in plants. ROS are suggested as being beneicial for seed germination, seedling growth, protection against pathogens and controlling the cell redox status [28][29][30][31][32][33][34][35][36][37][38][39][40]. H 2 O 2 is shown to be involved in the tolerance to various abiotic stresses acting as a secondary messenger [71], in cellular defense mechanisms against pathogens [72].…”

“…ROS are also proved to act as a positive signal in seed dormancy release [30][31][32][33]. The dual function of ROS in plants depends on the levels of antioxidant compounds, and enzyme activities release [34][35][36][37][38]. By this way, plants can eliminate potentially harmful ROS that is produced under stress conditions, or control ROS concentrations in order to regulate various signaling pathways [34][35][36][37][38].…”

The Dangers of Fat Metabolism and PUFA: Why You Don’t Want to be a Fat Burner

“…The glucuronosyltransferase enzyme, a drug clearance system in the liver, is similarly inhibited in the presence of PUFA [53]. In nature, the most abundant source of PUFA, plant seeds, lay dormant until germination is activated in part by decoupling stored PUFA from their enzymes through water driven H2O2 production [55]. The other significant natural source of PUFA is cold-water fish.…”