Bugs are bad, right? They can carry diseases from plant to plant. They can eat your crops. They can be very difficult to get rid of. But what if bugs biting into leaves could actually help you?
A team from Texas A&M AgriLife Research has recently discovered that some insect leaf-wounding in fruit and vegetable crops can actually be beneficial. The plants’ stress responses to the wounds led to increased antioxidant compounds before harvest, which made the produce better for humans.
“Many studies in the past supported this idea, but many others showed no differences,” said Luis Cisneros-Zevallos, Ph.D., AgriLife Research horticulture and food scientist. “In our study, we proved that wounding leaves in plants like those caused by insects produce healthier organic fruit.”
His research team, which also included Facundo Ibanez, Ph.D., molecular biologist Woo Young Bang, Ph.D., and horticulturist Leonardo Lombardini, Ph.D., manually created holes in the leaves of plants to mimic ones that might be caused by voracious insects. They conducted studies using strawberries as a crop model and applied various levels of wounding to the leaves a few days before harvesting fruit.
“We found several genes associated with sugar translocation and phenolic compound biosynthesis were overexpressed in the strawberry fruit,” said Ibanez.
Cisneros-Zevallos explained all plants have the ability to respond to the environment by activating the secondary metabolism as part of a defense mechanism or as part of an adaptation process. Environmental stimuli can also activate the primary metabolism, which moves the carbon source needed to produce those antioxidant compounds.
Cisneros-Zevallos said the idea that insects present in the field in organic farming could cause a stress response in plants and increase antioxidant compounds had been proposed by other scientists, but it had yet to be tested – until he and his team started poking holes in leaves. Studies published in the past reported on post-harvest wounding stress effects on different crops, but this experiment looked specifically at pre-harvest leaf-wounding.
Ibanez said their study emphasized fresh produce as a source of health-promoting compounds – and that insects in some way can be allies to achieve even healthier produce. “Healthier grown produce for the food industry can be a driving force for large-scale production and an attractive investment to relevant stakeholders,” he said.
These little holes actually represent big news. Understanding how antioxidants are produced by a simple stress like wounding can transform the way both organic and conventional produce industries operate. It may also allow the industry to adopt new tools based on pre-harvest stress to favor the accumulation of healthier antioxidants in fresh produce and processed foods, according to Cisneros-Zevallos.