Study Shows How a Common Fungus Reduces Cadmium Toxicity in Water Spinach

Jim Crocker
19th June, 2024

Study Shows How a Common Fungus Reduces Cadmium Toxicity in Water Spinach

Image Source: Natural Science News, 2024

Key Findings

  • The study by South China Normal University found that inoculating water spinach with the fungus Glomus versiforme (Gv) significantly improved the plant's growth and photosynthesis
  • Gv inoculation enhanced the plant's antioxidative defense system, increasing the activity of enzymes and antioxidants that protect against oxidative stress caused by cadmium (Cd)
  • The fungus also increased soil pH and reduced Cd uptake in water spinach, helping to protect the plant from Cd toxicity while still allowing it to aid in soil detoxification
The accumulation of heavy metals in soil poses significant environmental and health risks. One promising solution to mitigate this issue is phytoremediation, a process that uses plants to absorb, accumulate, and detoxify pollutants from the environment. A recent study conducted by South China Normal University has shed light on the physiological and molecular mechanisms by which arbuscular mycorrhizal fungus (AMF) affects cadmium (Cd) absorption, transport, and detoxification in Ipomoea aquatica, commonly known as water spinach[1]. The study employed a pot experiment to investigate the effects of the AMF species Glomus versiforme (Gv) on water spinach grown in soil supplemented with 5 mg Cd kg-1. The researchers aimed to understand how Gv inoculation impacts the plant's photosynthetic characteristics, Cd uptake, antioxidative system, and transcriptome. The results were promising. Gv inoculation significantly improved the photosynthetic characteristics and overall growth of water spinach. This is particularly important as photosynthesis is the process by which plants convert light energy into chemical energy, which is essential for their growth and survival. Enhanced photosynthesis indicates better plant health and vitality, which is crucial for effective phytoremediation. Furthermore, Gv colonization markedly boosted the activities of several antioxidative enzymes, including catalase (CAT), peroxidase (POD), and glutathione reductase (GR). These enzymes play a critical role in protecting plants from oxidative stress caused by heavy metals like Cd. The study also observed increased levels of antioxidants such as glutathione (GSH) and ascorbic acid (AsA), along with a higher total antioxidant capacity (TCA). These findings suggest that Gv inoculation helps water spinach to better manage oxidative stress, thereby enhancing its ability to survive and thrive in Cd-contaminated soils. Interestingly, the study found that Gv inoculation increased the pH of the rhizosphere soil (the soil region close to plant roots) and decreased the Cd concentrations and uptake in water spinach. This is significant because a higher pH can reduce the availability of Cd in the soil, making it less likely to be absorbed by the plant. This mechanism helps to protect the plant from Cd toxicity while still allowing it to play a role in phytoremediation. The researchers also conducted a transcriptome analysis to identify differentially expressed genes (DEGs) in water spinach roots colonized with Gv. They identified 2670 DEGs, of which 2008 were upregulated and 662 were downregulated. Notably, genes involved in antioxidative defense, such as POD, CAT, GR, dehydroascorbate reductase 2 (DHAR2), glutathione S-transferase U8 (GSTU8), and glutathione synthetase (GSHS), were significantly upregulated. Additionally, genes related to metal transport and detoxification, such as cytochrome P450 (Cyt P450), plant cadmium resistance protein 2 (PCR2), metal tolerance protein 4 (MTP4), ATP-binding cassette transporter C family member (ABCC), ABC-yeast cadmium factor 1 (ABC-YCF1), and metallothionein (MT), were also upregulated. These findings align with previous research on the role of AMF in enhancing plant tolerance to heavy metals. For instance, a study on white poplar (Populus alba) found that AMF inoculation improved plant growth and increased the expression of metallothioneins and polyamines, which are crucial for heavy metal detoxification[2]. Another study highlighted the role of AMF in improving the growth and antioxidant defense mechanisms in tomatoes grown in heavy metal-contaminated soils[3]. Both studies support the current findings that AMF can enhance the phytoremediation potential of plants by improving their physiological and molecular responses to heavy metal stress. Moreover, this study's identification of specific genes involved in Cd detoxification in water spinach provides valuable insights that could be used to enhance the efficiency of phytoremediation techniques. For example, genes such as Cyt P450 and GST, which were also found to be upregulated in Plantago major under cypermethrin stress, could be targeted to develop plants with improved detoxification capabilities[4]. In conclusion, the study by South China Normal University demonstrates that AMF inoculation, specifically with Glomus versiforme, can significantly enhance the phytoremediation potential of water spinach by improving its growth, photosynthetic efficiency, antioxidative defense, and molecular mechanisms for Cd detoxification. These findings contribute to a better understanding of how AMF can be utilized to mitigate heavy metal contamination in soils, offering a sustainable and effective approach to environmental remediation.

EnvironmentBiotechPlant Science


Main Study

1) Transcriptome analysis shows that Glomus versiforme decrease the accumulation and toxicity of cadmium in Ipomoea aquatic Forsk.

Published 18th June, 2024

Related Studies

2) Arbuscular mycorrhizal fungi restore normal growth in a white poplar clone grown on heavy metal-contaminated soil, and this is associated with upregulation of foliar metallothionein and polyamine biosynthetic gene expression.

3) Effect of Glomus mossae on accumulation efficiency, hazard index and antioxidant defense mechanisms in tomato under metal(loid) Stress.

4) Transcriptome analysis of Plantago major as a phytoremediator to identify some genes related to cypermethrin detoxification.

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