Melatonin Application Modifies Antioxidant Defense and Induces Endoreplication in Maize Seeds Exposed to Chilling Stress.

Izabela Kołodziejczyk,Małgorzata M Posmyk,Andrzej Kaźmierczak

doi:10.3390/ijms22168628

Izabela Kołodziejczyk, Małgorzata M Posmyk + Show 1 more

Open Access

https://doi.org/10.3390/ijms22168628

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Abstract

The aim of the study was to demonstrate the biostimulating effect of exogenous melatonin (MEL) applied to seeds via hydroconditioning. It was indicated that only well-chosen application technique and MEL dose guarantees success concerning seed germination and young seedlings growth under stress conditions. For maize seed, 50 μM of MEL appeared to be the optimal dose. It improved seed germination and embryonic axes growth especially during chilling stress (5 °C/14 days) and during regeneration after its subsided. Unfortunately, MEL overdosing lowered IAA level in dry seeds and could disrupt the ROS-dependent signal transduction pathways. Very effective antioxidant MEL action was confirmed by low level of protein oxidative damage and smaller quantity of lipid oxidation products in embryonic axes isolated from seeds pre-treated with MEL and then exposed to cold. The stimulatory effects of MEL on antioxidant enzymes: SOD, APX and GSH-PX and on GST-a detoxifying enzyme, was also demonstrated. It was indicated for the first time, that MEL induced defence strategies against stress at the cytological level, as appearing endoreplication in embryonic axes cells even in the seeds germinating under optimal conditions (preventive action), but very intensively in those germinating under chilling stress conditions (intervention action), and after stress removal, to improve regeneration.

Highlights

The majority of plant cultivation in spite of various agrotechnical procedures is maintained in suboptimal conditions for plants, and the changing climate exposes them to new stresses
Temperature conditions for germination are suboptimal and limiting [5], every low-cost improvement of sprouting might bring a measurable increase in harvests and economic benefits
Angular seeds, as dry corn, can be injured during rotations-as was observed in our preliminary experiments

Summary

Introduction

The majority of plant cultivation in spite of various agrotechnical procedures is maintained in suboptimal conditions for plants, and the changing climate exposes them to new stresses. Exists the necessity of searching for natural (biodegradable) factors, that through induction of internal defense strategies, might help plants overcome or adapt to stresses [1,2]. One of the most important cultivated plants in the world is corn (Zea mays L.). The plant is an important part of human diet and, in the face of the prevalence of food allergies, the absence of gluten in corn grains increases their value on the cereal market [3,4]. Green parts of corn are fodder for farm animals, and biodegradable, fully ecological materials are produced from those plant fibers. Temperature conditions for germination are suboptimal and limiting [5], every low-cost improvement of sprouting might bring a measurable increase in harvests and economic benefits

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