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Sweet Pepper cv. Lai Lai Ripeness Stage Influences Susceptibility to Mycotoxinogenic Alternaria alternata Causing Black Mold

Summary

This research shows that green and red peppers can both develop black mold caused by a fungus called Alternaria alternata, but at different rates depending on temperature. Red peppers are more susceptible to severe infection at room temperature, while both types are similarly affected during cold storage. Importantly, infected peppers can produce toxins harmful to human health, emphasizing the need for preventing fungal infection in pepper crops before harvest and storage.

Background

Black mold caused by Alternaria alternata is a common postharvest disease of sweet pepper that occurs during cold storage and transport, leading to significant produce losses. The pathogen is widespread in nature and can produce mycotoxins that pose health risks. Previous research on pepper disease has not fully characterized how ripeness stage influences Alternaria infection and mycotoxin production.

Objective

This study examined Alternaria alternata isolates infecting green (mature unripe) and red (ripe) sweet pepper fruit to understand how ripeness stage influences susceptibility to black mold. The specific objectives were to determine the combined effect of temperature and fruit ripening stage on Alternaria development, pathogenicity, and mycotoxin production.

Results

Black mold infected both green and red fruit, but lesion development was significantly larger on red fruit at 22°C compared to 7°C. Conidial germination rates were similar on both fruit types, but appressoria formation was significantly more prevalent on red peppers at higher temperatures. Microscopic studies revealed that fungal penetration occurred through cuticle wounds with intercellular hyphal growth, and vascular bundles were destroyed in red fruit but remained intact in green fruit. High levels of mycotoxins were detected in both green and red infected fruit at 22°C.

Conclusion

Mature green pepper fruit are susceptible to Alternaria infection and can produce mycotoxins similar to ripe red fruit, with disease progression influenced by temperature. Field treatments to prevent pathogen establishment at the mature green stage are essential to mitigate postharvest black mold and associated mycotoxin contamination risks.
  • Published in:Plant Pathology Journal,
  • Study Type:Experimental Study,
  • Source: PMID: 40468876, DOI: 10.5423/PPJ.OA.08.2024.0130
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