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

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.

Exogenous melatonin improves germination rate in buckwheat under high temperature stress by regulating seed physiological and biochemical characteristics

“…However, treatment with 200 µM MT under high-temperature conditions significantly enhanced the germination rate and potential, seed radicle growth, and fresh weight. These findings align well with prior research, which showed that an appropriate concentration of MT can bolster germination in the seed of rice, corn, wheat, and other seeds under stressful conditions, and stimulate radicle lengthening ( Kołodziejczyk, Kaźmierczak & Posmyk, 2021 ; Lei et al, 2021 ; Yu et al, 2022 ). In this study, soaking buckwheat seeds with MT could alleviate the inhibition effect of high temperature on seed germination.…”

Melatonin in Plant Defense against Abiotic Stress

“…In a study performed on Pistacia vera (L.) grown under cold stress, application of melatonin caused a significant decrease in the expression of oxidative stress biomarkers, with a subsequent decrease in sugar, proline, and GABA content [140]. Melatonin treatment enhances seed germination and prevents protein and lipid oxidation in embryonic cells of Capsicum annum and Zea mays, besides causing an increase in the antioxidant levels [141,142]. Turk and Genisel reported that application of melatonin in maize plays an important role in improving plant growth attributes and in protecting plants from oxidative damage via reduction in the ROS levels [143].…”

Molecular dynamics of seed priming at the crossroads between basic and applied research

“…Jasmonic acid (JA) has been used as a priming agent to treat tomato seeds, enhancing the seedling ability to withstand nematode attacks (Bali et al 2020 ). Priming with brassinosteroids (BRs) significantly enhanced tolerance to heavy metal toxicity (Basit et al 2021 , 2022 ), and drought (Huang et al 2020 ), whereas the use of melatonin contributed to improved cold tolerance (Cao et al 2019 ; Kołodziejczyk et al 2021 ). Due to the complexity of phytohormone metabolism and regulatory networks, the selection of suitable conditions and effective molecules for hormopriming depends on a deeper knowledge of several key molecular players and the way they could contribute to boosting germination (Bryksova et al 2020 ).…”