Effects of Naphthazarin (DHNQ) Combined with Lawsone (NQ-2-OH) or 1,4-Naphthoquinone (NQ) on the Auxin-Induced Growth of Zea mays L. Coleoptile Segments

Abstract

Naphthoquinones, plants secondary metabolites are known for their antibacterial, antifungal, anti-inflammatory, anti-cancer and anti-parasitic properties. The biological activity of naphthoquinones is connected with their ability to generate reactive oxygen species and to modify biological molecules at their nucleophilic sites. In our research, the effect of naphthazarin (DHNQ) combined with 2-hydroxy-1,4-naphthoquinone (NQ-2-OH) or 1,4-naphthoquinone (1,4-NQ) on the elongation growth, pH changes of the incubation medium, oxidative stress and redox activity of maize coleoptile cells were investigated. This paper describes experiments performed with maize (Zea mays L.) coleoptile segments, which is a classical model system to study plant cell elongation growth. The data presented clearly demonstrate that lawsone and 1,4-naphthoquinone combined with naphthazarin, at low concentrations (1 and 10 nM), reduced the endogenous and IAA-induced (Indole-3-Acetic Acid) elongation growth of maize coleoptile segments. Those changes in growth correlated with the proton concentration in the incubation medium, which suggests that the changes in the growth of maize coleoptile segments observed in the presence of naphthoquinones are mediated through the activity of PM H+-ATPase. The presence of naphthoquinones induced oxidative stress in the maize coleoptile tissue by producing hydrogen peroxide and causing changes in the redox activity. Moreover, the incubation of maize segments with both naphthoquinones combined with naphthazarin resulted in lipid peroxidation and membrane damage. The regulation of PM H+-ATPase activity, especially its inhibition, may result from two major types of reaction: first, a direct interaction between an enzyme and naphthoquinone, which leads to the covalent modification of the protein thiols and the generation of thioethers, which have been found to alter the activity of the PM H+-ATPases; second, naphthoquinones induce reactive oxygen species (ROS) production, which inhibits PM H+-ATPases by increasing cytosolic Ca2+. This harmful effect was stronger when naphthazarin and 1,4-naphthoquinone were added together. Taking these results into account, it can be suggested that by combining naphthoquinones in small quantities, an alternative to synthetic pesticides could be developed.

Some New Methodological and Conceptual Aspects of the “Acid Growth Theory” for the Auxin Action in Maize (Zea mays L.) Coleoptile Segments: Do Acid- and Auxin-Induced Rapid Growth Differ in Their Mechanisms?

“…To the best of our knowledge, the growth, medium pH and membrane potential have never been measured simultaneously. Generally, the characteristic IAA-induced changes in the membrane potential of the coleoptile cells that were observed here (the initial, transient depolarisation followed by the hyperpolarisation of the membrane) are in good agreement with other authors [ 22 , 23 , 24 , 25 , 42 , 57 , 58 ]. However, taking into account our experimental conditions (membrane potential was measured simultaneously with the growth and medium pH), it should be pointed out that these characteristic changes differed in their kinetics compared to those in the articles cited above.…”

Genome-Wide Association Study Uncovers Novel Genomic Regions Associated With Coleoptile Length in Hard Winter Wheat

“…Further, phytochrome A (PHY A) protein identified in the QCL.sdsu-4BS candidate region is of specific importance with respect to coleoptile length. In rice, phytochrome A gene is well known to affect coleoptile elongation, plant height, and internode elongation either directly or by affecting jasmonate signaling genes (Garg et al, 2006;Riemann et al, 2008). Apart from these genes, we also found jacalin-like lectin, related to Horcolin protein specifically expressed in barley coleoptiles (Grunwald et al, 2007) and putative 2-oxoglutarate-dependent dioxygenase (Table 3), related to a versatile enzyme family catalyzing biosynthesis and catabolism of auxins and gibberellins (Farrow and Facchini, 2014).…”

“…Phytohormones are the signaling molecules, which play a crucial role in the development and physiological processes in plants (Rudnicka et al, 2019). Specifically, auxins are a major group of phytohormones, which affect coleoptile length in grass species by inducing cell elongation either directly (Vanneste and Friml, 2009;Paque and Weijers, 2016), or by interacting with other plant hormones such as ethylene (Woodward and Bartel, 2005).…”

Bioelectrosynthetic Conversion of CO2 Using Different Redox Mediators: Electron and Carbon Balances in a Bioelectrochemical System

“…Different mediators have been studied extensively in many microbial fuel cell systems [29,[38][39][40][41][42], whereas less attention has been paid to microbial electrosynthesis for CO 2 conversion. A higher concentration of such mediators and concomitantly larger concentration gradient across the cell membrane may damage the cellular structure when they are transported through the membrane [43,44]. Compared to NR (molecular weight, 288.77) and HNQ (MW 174.15), the molecular weight of HQ is relatively small (MW 110.11).…”