Natural Proteins to Stop Fruit Fungus After Harvest

Jenn Hoskins
24th April, 2024

Natural Proteins to Stop Fruit Fungus After Harvest

Image Source: Natural Science News, 2024

Key Findings

  • UC Riverside study finds proteins (PGIPs) can reduce fungal growth on fruits, aiding post-harvest freshness
  • PGIPs remain effective across temperatures from -20 to 42 °C, suitable for various storage conditions
  • Treated tomatoes showed over 50% less disease spread, highlighting PGIPs as potential eco-friendly fungicide alternatives
In recent years, the challenge of maintaining the freshness and quality of fruits and vegetables post-harvest has become increasingly significant. This is not only a matter of reducing economic losses in the agricultural sector but also crucial for public health. The Dietary Guidelines for Americans highlight the importance of fruit and vegetable consumption for maintaining a healthy diet and preventing chronic diseases[2]. However, the shelf life of these nutritious foods is often compromised by fungal infections, which lead to spoilage and waste. Traditional methods for controlling postharvest fungal diseases have relied heavily on chemical fungicides. While effective, these chemicals pose risks to human health and the environment[3]. As such, there's a growing demand for safer, more sustainable alternatives to protect our food supply. This is where a new study from the University of California Riverside comes into play[1]. The research focuses on a group of plant proteins known as polygalacturonase inhibiting proteins (PGIPs). These proteins have a specific role in plants: they inhibit the action of polygalacturonases (PGs), which are enzymes secreted by fungi to break down plant cell walls. By doing so, PGIPs help to prevent fungal pathogens from invading and causing disease in plants. Previous research had established that a particular PGIP from the common bean, Phaseolus vulgaris (PvPGIP2), could inhibit the growth of harmful fungi on agar plates. The latest study builds on this foundation, exploring the practical application of PGIPs as a natural defense against fungal infections in post-harvest produce. Researchers tested both purified PGIPs and yeast strains engineered to secrete PGIPs against fungal growth on tobacco leaves. They found that applying these proteins could effectively reduce the growth of fungi and the size of necrotic lesions caused by the pathogens. Specifically, a concentration of 0.75 mg/mL or higher of PGIPs significantly diminished the damage caused by Botrytis cinerea, a common and destructive fungal pathogen. Moreover, the study assessed the stability of PGIPs under various temperatures. It was found that the full-length PvPGIP2 maintained its activity after 24 hours across a range of temperatures from -20 to 42 °C. This is an important characteristic for any postharvest treatment, as it must withstand different storage and transport conditions. The truncated version of the protein, tPvPGIP2_5-8, showed some loss of efficacy at 42 °C, suggesting that the full-length protein might be more robust for practical use. The promising results extended beyond the laboratory setting. When purified PvPGIP2 was applied to tomatoes inoculated with B. cinerea, the incidence and spread of the disease were more than halved compared to untreated controls. This demonstrates the potential of PGIPs to act as an eco-friendly alternative to chemical fungicides on actual produce. The implications of this research are significant. With the development of RNA interference (RNAi)-based fungicides and other non-chemical treatments gaining attention[3], the use of PGIPs adds another tool in the arsenal against postharvest fungal diseases. This aligns with the broader efforts to reduce chemical residues on food, as seen in the integration of heat therapy with reduced fungicide applications[4]. In summary, the University of California Riverside's study opens up new avenues for sustainable agriculture by providing an effective, environmentally friendly method to protect fruits and vegetables from fungal spoilage. This could lead to longer shelf lives for produce, reduced food waste, and improved access to healthy foods—an outcome that would resonate with the goals set out in the Dietary Guidelines for Americans[2] and support the health of consumers worldwide.

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References

Main Study

1) Polygalacturonase-inhibiting proteins as an exogenously applied natural solution for prevention of postharvest fungal infections.

Published 23rd April, 2024

https://doi.org/10.1016/j.synbio.2024.04.002

Related Studies

2) Adults Meeting Fruit and Vegetable Intake Recommendations - United States, 2019.

https://doi.org/10.15585/mmwr.mm7101a1

3) Control of postharvest fungal diseases in fruits using external application of RNAi.

https://doi.org/10.1111/1750-3841.15816

4) Control of postharvest diseases of fruit by heat and fungicides: efficacy, residue levels, and residue persistence. A review.

https://doi.org/10.1021/jf201899t


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