Opening a container of berries and finding them covered in mold is a common disappointment, leading to significant economic losses and food waste. Gray mold and other fungal pathogens can cause fruit to rot, but researchers have discovered a potential solution using compounds derived from sunflower crop waste. These natural compounds could offer an eco-friendly alternative for protecting fruit against post-harvest diseases, reducing the need for chemical fungicides.
While sunflowers are primarily cultivated for their seeds and oil, the flower stems, known as receptacles, are typically considered waste products. Recognizing sunflowers’ natural resistance to many plant diseases, a team of researchers led by Xiao-Dong Luo and Yun Zhao set out to explore whether the receptacles might contain chemical constituents responsible for this protective effect.
The researchers extracted compounds from sunflower stems using methanol and ethyl acetate. They isolated and identified the components in these extracts, with a particular focus on diterpenoids, known for their biological activity. Their investigation revealed 17 diterpenoids, including four previously unknown compounds.
Most of the diterpenoids displayed activity against gray mold, a common fungal pathogen. Notably, four of the compounds, including two newly identified ones, effectively disrupted the plasma membrane of the fungus, causing cell leakage and preventing the formation of biofilms.
In their experiments, the researchers briefly applied the receptacle extracts to blueberries, allowing them to dry before injecting the fruit with mold spores. Over a six-day period, the receptacle extracts protected nearly half of the blueberries from mold growth.
The results suggest that sunflower stem extracts could serve as a natural biocontrol agent to combat post-harvest diseases in fruit, offering a sustainable alternative to chemical fungicides and contributing to the reduction of food waste and economic losses in the food industry.