Melatonin and Nitric Oxide Can Jointly Help Overcome Heavy Metal Toxicity in Plants
- Date
- 2023/12/20
- Writer
- 사이트매니저
- Hit
- 1491
Melatonin and Nitric Oxide Can Jointly Help Overcome
Heavy Metal Toxicity in Plants
A new study reports that combined melatonin and nitric oxide application enhance plant resistance to heavy metal toxicity.
Environmental contamination by heavy metals is a global health hazard. Heavy metals absorbed by plants find their way into the food chain. Plant compounds, such as melatonin (MT) and nitric oxide (NO), enhance their tolerance and resistance to heavy metal stress. In a new study, researchers demonstrated that combined MT and NO application increases the soybean plant tolerance to lead and cadmium toxicity by regulating the activation of related antioxidant and molecular transcription factors.
Image title:
Dual action of melatonin and nitric oxide increase resistance of soybean plants
to lead and cadmium toxicities.
Image caption:
A combination of melatonin (MT) and nitric oxide (NO) is more effective in
mitigating Pb and Cd stress in soybean plants than their individual
administrations. The combined application of MT and NO significantly enhance
plant tolerance to heavy metal toxicities by regulating the inherent
antioxidant and molecular signaling pathways.
Image credit:
The authors
License type:
Original Content
Usage
restrictions: Cannot be reused without permission.
The expansion of industrialization and mining has led
to significant increase in the heavy metal accumulation in the soil and aquatic
environments. Heavy metals, such as lead (Pb) and cadmium (Cd), adversely
affect plant growth through reduction in nutrient uptake, membrane integrity,
and photosynthetic activity, which causes chlorosis (yellowing of leaves due to
lack of chlorophyll). In response to such adverse conditions, plants adopt
defensive strategies, such as enhanced antioxidant activity, hormonal
regulation, enhanced membrane integrity, and activation of stress response
transcription factors.
Melatonin (MT) is an indole-amine plant stress
alleviator and a remarkable plant growth regulator. It enhances plant tolerance
to biotic and abiotic stresses, including heavy metal toxicities. Nitric oxide
(NO) regulates various physiological, metabolic, and pathophysiological
processes in plants under stress. Moreover, induced NO expression in plants may
regulate their responses to stresses such as heavy metal toxicity. However,
although the individual MT and NO roles are understood, the role of their
combined application on plant stress tolerance and growth is unclear.
To fill this knowledge gap, a group of researchers,
including an international researcher and first author of the study, Dr.
Muhammad Imran, under the guidance of Professor In-Jung Lee from Kyungpook
National University, Republic of Korea, investigated the impact of a
combination of MT and NO on plant growth and tolerance under Pb and Cd toxicity
in soybean plants. Their study was made available online on September 22, 2022,
and was published in Volume 308, Part 3 of the journal Chemosphere on December 01, 2022.
“To clarify the roles of MT and NO in regulating the
antioxidant enzyme activities, we investigated plant growth, nutrient uptake,
and their effects on mitogen-activated protein kinase (MAPK) cascades under Cd
and Pb toxicity in soybean plants. We assessed the influence of combined MT and
NO application on the gene expression involved in NO, metal-regulatory
transcription factors (MTFs), MAPKs, and calcium-dependent protein kinases
(CDPK) cascades in response to metal toxicity,” explains Prof. Lee.
Surface sterilized soybean seeds were used to grow
saplings, which were then treated with MT, sodium nitroprusside (SNP, NO
donor), 2-4-carboxyphenyl-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide (cPTIO,
NO scavenger), Pb, and Cd. Soon after, the plants were divided into four groups
based on the treatment administered: control (no treatment), Pb only, Cd only,
and a combination of Pb and Cd. Each group had subsets where the following
treatments were applied: only heavy metal, metal and SNP, metal and MT, metal
with both SNP and MT, and metal with MT and cPTIO. After eight days, they
assessed various parameters like plant growth, antioxidant enzyme activity, photosynthetic
capabilities, phytohormone levels, etc.
They
found that a combined MT and NO application
(MT/NO) was more beneficial than MT or NO alone in plants under Pb and Cd
stress. MT/NO increased photosynthetic efficiency while reducing oxidative
stress in the plants, causing an improvement in biomass. MT/NO increased the uptake of calcium and
potassium ions and reduced the Pb and Cd mobilization
from contaminated soil into the plants. Furthermore, organic acid
exudation into the rhizosphere increased significantly, mitigating the overall
metal toxicity.
Further
analyses revealed that MT/NO minimized metal toxicity by lowering the
endogenous levels of phytohormones, abscisic acid, and jasmonic acid. This finding accompanied the
downregulation of the abscisic
acid biosynthetic gene (NCED3) and the upregulation of the catabolism-related
genes (CYP707A1 and CYP707A2).
The
exogenous MT and NO application
on soybean plants
significantly increased the endo-MT and endo-S-nitrosothiol levels, mitigating the heavy metal stress in the plants. RT-qPCR analyses revealed
increased mRNA expressions
of related
genes, gmNR and gmGSNOR, further corroborating the above
mechanism.
Enzymes such as MAPK and CDPK are essential
in plant responses to biotic and abiotic stresses. MT/NO upregulated the MAPK
and CDPK cascades in the presence of Pb and Cd, increasing plant tolerance levels. Furthermore, MT- and NO-mediated the upregulation of the metal
response element-binding transcription factor (MTF-1) and
the stress response gene (WARKY27), improving heavy metal
detoxification and tolerance.
Summarizing the importance of their study, Prof. Lee
concludes, “A positive role of MT and NO in the modulation of plant defense
mechanisms via regulating the levels of antioxidants, calcium signaling, and
MAPK cascades to reduce oxidative stress induced by toxic metals such as Pb and
Cd.”
In conclusion, this study reveals that MT/NO mitigates
Pb and Cd toxicities by activating related antioxidant and molecular
transcription factors in soybean plants, paving the way for future research on
overcoming heavy metal toxicities.
Reference
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Authors Title of original paper: |
Muhammad Imrana, Abdul Latif Khanc,
Bong-Gyu Muna, Saqib Bilalb, Shifa Shaffiquea,
Eun-Hae Kwona, Sang-Mo Kanga, Byung-Wook Yuna,
and In-Jung Lee a,* Melatonin and nitric oxide: Dual players
inhibiting hazardous metal toxicity in soybean plants via molecular and
antioxidant signaling cascades |
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Journal: |
Chemosphere |
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DOI: |
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Affiliations |
aDepartment of Applied Biosciences, Kyungpook National
University, Daegu, 41566, Republic of Korea bNatural & Medical Sciences Research Center, University of
Nizwa, Nizwa 616, Oman cDepartment of Engineering Technology, College of Technology,
University of Houston, Sugar Land, TX 77479, USA |
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*Corresponding
author’s email |
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About Kyungpook National University
Kyungpook National University
(KNU) is a national university located in Daegu, South Korea.
Founded in 1946, it is
committed to becoming a leading global university based on its proud and
lasting tradition of truth, pride, and service. As a comprehensive national
university representing the regions of Daegu and Gyeongbuk Province, KNU has been
striving to lead Korea’s national and international development by fostering
talented graduates who can serve as global community leaders.
Website: https://en.knu.ac.kr/main/main.htm
About Professor In-Jung Lee from Kyungpook National University
Professor
In-Jung Lee is a professor at the Department of Applied Biosciences, Kyungpook
National University (KNU), South Korea. Professor Lee is an avid researcher in
the fields of plant physiology and hormones and plant-microbe interactions. His
research consistently demonstrated dedication and innovation in plant stress
physiology. He has also achieved the goal of studying the importance of
melatonin and nitric oxide and their role in plant development and conducted
valuable research. This not only highlights his expertise but also showcases
his significant contributions. He has more than 500 publications to his credit
in journals with high impact factors and an impressive h-index of 69 (Web of
Science).
About Professor Byung-Wook Yun from Kyungpook National University
Dr.
Byung-Wook Yun is a professor at the Department of Applied Biosciences,
Kyungpook National University (KNU), South Korea. Dr. Yun specializes in plant
immunity, defense mechanisms, and disease resistance. He has more than 100 publications to his credit in journals with high
impact factors and an impressive h-index of 36 (Web of Science). He earned his
Ph.D. from KNU in the field of Plant Biochemistry and has experience in
investigating the role of nitric oxide (NO), a small redox-active signaling
molecule, in the plant immune system at the University of Edinburgh for more
than 10 years. His team is currently working on stress biology to understand
the mechanism of how NO plays a role in modulating stress responses. In
addition, his team aims to construct a nanoparticle-NO system as an enhancer to
improve plant growth and tolerance to environmental stresses.
About Dr. Muhammad Imran from the National
Institute of Agriculture Science
Dr.
Imran is a senior researcher at the National Institute of Agriculture Science,
Rural Development Administration, Republic of Korea. He received his postdoc
and Ph.D. at Kyungpook National University in 2022 and possesses extensive
expertise in Plant Physiology, Phytohormonal Signaling, Stress Physiology,
Metabolites, and Plant-Microbe Interaction. He has published more the 50
research articles in journals of international repute.