Tricky treats: Why pumpkins accumulate pollutants
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The gourd family of plants comprising pumpkins, zucchini, melons, cucumbers and more are known to accumulate high levels of pollutants in their edible parts. Understanding the mechanism behind the pollutant accumulation is crucial to creating safer produce.
view moreCredit: INUI Hideyuki
Pumpkins, squash, zucchini and their relatives accumulate soil pollutants in their edible parts. A Kobe University team has now identified the cause, making it possible to both make the produce safer and create plants that clean contaminated soil.
The gourd family of plants comprising pumpkins, zucchini, melons, cucumbers and more are known to accumulate high levels of pollutants in their edible parts. Kobe University agricultural scientist INUI Hideyuki says: “The pollutants don’t easily break down and thus pose a health risk to people who eat the fruit. Interestingly, other plants don’t do this and so I became interested in why this happens in this group specifically.”
In previous studies, the Kobe University researcher and his team identified a class of proteins from across the gourd family that bind to the pollutants, thus enabling them to be transported through the plant. Earlier this year they published that the shape of the proteins and their binding affinity to the pollutants influence the accumulation in the aboveground plant parts. “However, these proteins exist in many other plants, and even among the gourds, there are varieties that are more prone to accumulating pollutants than others. We then noticed that in the highly accumulating varieties, there are higher concentrations of the protein in the sap,” says Inui. Thus, his team turned their attention to the secretion of the pollutant-transporting protein into the plant sap.
In the journal Plant Physiology and Biochemistry, the Kobe University team now publish that they could show that the protein variants from the highly accumulating plants are indeed exported into the sap, whereas other variants are retained in the cells. They could also pinpoint that this is likely due to a small difference in the protein’s amino acid sequence that acts as a tag that tells the cell which proteins to retain within. The team proved their point by showing that unrelated tobacco plants in which they introduced the highly accumulating protein versions also exported the protein into the plant sap. Inui explains: “Only secreted proteins can migrate inside the plant and be transported to the aboveground parts. Therefore, this seems to be the distinguishing factor between low-pollution and high-pollution plant varieties.”
Understanding the mechanism behind pollutant accumulation is crucial to creating safer produce. “By controlling the behavior of contaminant-transporting proteins, through genetic modification of their pollutant-binding ability or its excretion into the plant sap, we believe it will be possible to cultivate safe crops that do not accumulate harmful chemicals in their edible parts,” says Inui.
But the Kobe University researcher has a broader vision. He explains: “I started this research because I was looking for plants that can detect and digest pollutants effectively. Therefore, I also envision that we could use the knowledge gained through this work for creating plants that are more effective in absorbing soil pollutants. This could turn into a technology for cleaning contaminated soils.”
This research was funded by the Japan Society for the Promotion of Science (grant 23241028) and the Murao Educational Foundation.
Kobe University is a national university with roots dating back to the Kobe Higher Commercial School founded in 1902. It is now one of Japan’s leading comprehensive research universities with over 16,000 students and over 1,700 faculty in 11 faculties and schools and 15 graduate schools. Combining the social and natural sciences to cultivate leaders with an interdisciplinary perspective, Kobe University creates knowledge and fosters innovation to address society’s challenges.
Journal
Plant Physiology and Biochemistry
Method of Research
Experimental study
Subject of Research
Not applicable
Article Title
Extracellular secretion of major latex-like proteins related to the accumulation of the hydrophobic pollutants dieldrin and dioxins in Cucurbita pepo
Article Publication Date
29-Oct-2025
Soil ‘memory’ can help plants respond to drought
New research has found that microbial communities in soil have the capacity to remember and adapt to past environmental events, helping plants to withstand drought stress.
Experts from the University of Nottingham's School of Biosciences in collaboration with scientists from the University of Kansas found that soil microbes carry a long-term memory of past climate, and that this memory can shape how some plants respond to new droughts. The findings have been published today in Nature Microbiology.
Droughts are becoming more frequent and severe due to climate change, posing major threats to both crops and natural ecosystems.
In this study, researchers investigated how long-term differences in rainfall shape soil microbes and whether these changes influence how plants respond to future droughts.
They analysed soils from six prairies in Kansas, USA, that experience very different levels of rainfall and identified specific microbes and microbial genes linked to rainfall history. They then tested how these microbial legacies affected the performance of plants during a controlled drought experiment. They found that microbes from drier soils helped a native prairie grass cope better with drought, but they did not provide the same benefit to maize.
Dr Gabriel Castrillo, the group leader from the School of Biosciences at the University of Nottingham explains how the results of this study could help develop climate resistant crops in the future: “Soil microbial communities have the capacity to adapt quickly to environmental shifts, and help plants withstand drought stress. Remarkably, these microbial communities can also "remember" past environmental conditions, a phenomenon known as legacy effects or ecological memory. Understanding these microbial legacies could help us design more resilient agricultural systems and protect ecosystems under future climate stress.”
Journal
Nature Microbiology
Method of Research
Experimental study
Subject of Research
Not applicable
Article Title
Precipitation legacy effects on soil microbiota facilitate adaptive drought responses in plants
Article Publication Date
30-Oct-2025
Synthetic biology to supercharge photosynthesis in crops
Nanoscale compartments used to target plants’ biggest bottleneck
University of Sydney
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Dr Taylor Szyszka from the ARC Centre of Excellence in Synthetic Biology and School of Chemistry at the University of Sydney.
view moreCredit: Stefanie Zingsheim/University of Sydney
Australian researchers have created tiny compartments to help supercharge photosynthesis, potentially boosting wheat and rice yields while slashing water and nitrogen use.
Researchers from Associate Professor Yu Heng Lau’s group at the University of Sydney and Professor Spencer Whitney’s group at Australian National University have spent five years tackling a fundamental problem: how can we make plants fix carbon more efficiently?
The team engineered nanoscale ‘offices' that can house an enzyme called Rubisco in a confined space, enabling scientists to fine tune compatibility for future use in crops, which should allow them to produce food with fewer resources.
Their research is published in Nature Communications.
Rubisco is a common enzyme in plants that is essential for ‘fixing’ carbon dioxide for photosynthesis, the chemical process that uses sunlight to make food and energy for plants.
“Despite being one of the most important enzymes on Earth, Rubisco is surprisingly inefficient,” said lead researcher Dr Taylor Szyszka from the ARC Centre of Excellence in Synthetic Biology and School of Chemistry at the University of Sydney.
“Rubisco is very slow and can mistakenly react with oxygen instead of CO2 which triggers a whole other process that wastes energy and resources. This mistake is so common that important food crops such as wheat, rice, canola and potatoes have evolved a brute-force solution: mass-produce Rubisco,” she said.
In some leaves, up to 50 percent of the soluble protein is just copies of this one enzyme, representing a huge energy and nitrogen expense for the plant.
“It's a major bottleneck in how efficiently plants can grow,” said Davin Wijaya, a PhD candidate at the Australian National University, who co-led the study.
Some organisms solved this problem millions of years ago. Algae and cyanobacteria house Rubisco in specialised compartments and supply them with concentrated CO2. They’re like tiny home offices that allow the enzyme to work faster and more efficiently, with everything it needs close at hand.
Scientists have been trying for years to install these natural CO2-concentrating systems into crops. But even the simplest of these Rubisco-containing compartments from cyanobacteria, called carboxysomes, are structurally complicated. They need multiple genes working in precise balance and can only house their native Rubisco.
The Lau and Whitney team took a different approach, using encapsulins. These are simple bacterial protein cages that require just one gene to build. Think of it like Lego blocks that automatically snap into place, rather than assembling complicated flat-pack furniture.
To load Rubisco inside, the researchers added a short ‘address tag’ of 14 amino acids to the enzyme that, like a postcode, directs the enzyme to its destination inside the assembling compartment.
The team tested three Rubisco varieties: one from a plant and two from bacteria. They found that timing matters. For more complex forms of the enzyme, they needed to build Rubisco first, then build the protein shell around it.
“Rubisco didn't assemble properly when trying to do both at once,” Mr Wijaya said.
Dr Szyszka said: “Another cool advantage of our system is that it's modular. Carboxysomes can only package their own Rubisco, whereas our encapsulin system can package any type.
“Most excitingly we found the pores in the encapsulin shell allow for the entry and exit of Rubisco’s substrate and products,” she said.
The researchers emphasise this is just a proof of concept. They need to add the additional components that will give Rubisco the high-performance environment it needs. Early-stage plant experiments are already under way at ANU.
“We know we can produce encapsulins in bacteria or yeast; making them in plants is the next sensible step. Our preliminary results look promising,” Mr Wijaya said.
If successful, crops with this elevated CO2-fixing technology could produce higher yields while using less water and nitrogen fertiliser. These are critical advantages as climate change and population growth put pressure on global food systems.
INTERVIEWS
Dr Taylor Szyszka | taylor.szyszka@sydney.edu.au
Associate Professor Yu Heng Lau | yuheng.lau@sydney.edu.au
Davin Wijaya | davin.wijaya@anu.edu.au
MEDIA ENQUIRIES
University of Sydney
Marcus Strom | marcus.strom@sydney.edu.au marcus.strom@sydney.edu.au| +61 474 269 459
Outside of work hours, please call +61 2 8627 0246 (directs to a mobile number) or email media.office@sydney.edu.au.
ARC Centre of Excellence in Synthetic Biology
Mary O’Malley | mary.omalley@mq.edu.au | +61 438 881 124
RESEARCH
Szyszka, T. and Wijaya, D. et al ‘Reprogramming encapsulins into modular carbon-fixing nanocompartments’ (Nature Communications 2025) DOI: 10.1038/s41467-025-65307-9.
DECLARATION
The authors declare no competing interests. Funding was received from the Australian Research Council.
Journal
Nature Communications
Method of Research
Experimental study
Subject of Research
Cells
Article Title
Reprogramming encapsulins into modular carbon-fixing nanocompartments
Article Publication Date
30-Oct-2025
