How Melatonin and Plant Hormones Help Cherry Tomatoes Fight Cadmium Damage

Greg Howard
28th July, 2024

How Melatonin and Plant Hormones Help Cherry Tomatoes Fight Cadmium Damage

Image Source: Natural Science News, 2024

Key Findings

  • Researchers at Foshan University found that combining melatonin and brassinosteroids reduces cadmium stress in cherry tomato plants
  • This combination decreases cadmium accumulation in the shoots and boosts antioxidant activities
  • It also improves potassium balance and content in both roots and shoots, enhancing overall plant health
Increased anthropogenic activities over the last decades have led to a gradual increase in cadmium (Cd) content in the soil, making Cd accumulation in plants a serious threat to the health of animals and humans. Cd is highly mobile in soil, which exacerbates its uptake by plants and subsequent entry into the food chain. Addressing this issue, a recent study by researchers at Foshan University investigated the role of combined and separate exogenous application of melatonin (Mel) and brassinosteroids (BR) on Cd stress in cherry tomato plants[1]. Cd stress significantly reduces tomato growth by inducing oxidative stress and reducing potassium (K+) uptake in roots and shoots. This study found that the combined application of Mel and BR mitigated the detrimental effects of Cd in tomatoes through several mechanisms. Firstly, it reduced Cd accumulation in the shoot. Secondly, it increased the activities of various antioxidants such as superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APX), and glutathione reductase (GR). Thirdly, it triggered higher expression of genes related to Cd vacuolar sequestration (Na+/H+ EXCHANGER, SlNHX1; NATURAL RESISTANCE-ASSOCIATED MACROPHAGE PROTEIN 6, SlNRAMP6), and Cd transport and detoxification (HEAVY-METAL-ASSOCIATED 3, SlHMA3; PLANT CADMIUM RESISTANT 2, SlPCR2). Lastly, it improved plant K+ homeostasis and content in both root and shoot tissues. The study's findings align with previous research that highlights the critical role of K+ in plant stress responses. For example, K+ channels are known to mediate plant adaptive responses to various abiotic and biotic stresses, including drought, salinity, and oxidative stress[2]. The reduction in gene expression of the K+-permeable outward rectifying channel (SlGORK3) and the transcriptional upregulation of high-affinity potassium transporter 5 (SIHAK5) under Cd stress observed in this study further support the importance of K+ homeostasis in stress tolerance. Interestingly, the study also revealed tissue-specific effects of Mel and BR. Melatonin was more effective in improving Cd tolerance in the shoot, while BR showed more pronounced benefits in the roots. This tissue-specific regulation is crucial because it allows for targeted interventions depending on the specific needs of the plant tissues. The combined application of Mel and BR was found to be effective in both tissues, making it a practical tool to reduce Cd accumulation and mitigate its negative effects on plant growth. The role of plant hormones like BR in stress tolerance has been well-documented. BR regulates a wide range of biological processes that lead to tolerance of various stresses, including salinity and oxidative stress[3]. The current study expands on this knowledge by demonstrating that BR, when used in combination with Mel, can also mitigate Cd stress. Moreover, the study's findings on antioxidant activities align with previous research on halophytes, plants adapted to high salt environments. Halophytes have been shown to possess efficient mechanisms for reactive oxygen species (ROS) detoxification, which is essential for salinity stress tolerance[4]. The increased activities of antioxidants like SOD and CAT in the current study suggest that similar mechanisms may be at play in Cd stress tolerance. In summary, the study from Foshan University provides valuable insights into the role of Mel and BR in mitigating Cd stress in cherry tomato plants. By reducing Cd accumulation, enhancing antioxidant activities, and improving K+ homeostasis, the combined application of Mel and BR offers a practical solution to reduce Cd's negative effects on plant growth. This research not only builds on previous findings but also opens new avenues for developing effective strategies to enhance plant stress tolerance.

AgricultureBiochemPlant Science

References

Main Study

1) Revealing mechanistic basis of ameliorating detrimental effects of cadmium in cherry tomatoes by exogenous application of melatonin and brassinosteroids.

Published 26th July, 2024

https://doi.org/10.1016/j.ecoenv.2024.116768

Related Studies

2) Going beyond nutrition: regulation of potassium homoeostasis as a common denominator of plant adaptive responses to environment.

https://doi.org/10.1016/j.jplph.2014.01.009

3) The physiological and molecular mechanism of brassinosteroid in response to stress: a review.

https://doi.org/10.1186/s40659-018-0195-2

4) ROS homeostasis in halophytes in the context of salinity stress tolerance.

https://doi.org/10.1093/jxb/ert430


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