Researchers in the United States have discovered the mechanisms a problematic weed uses to over-run and secure itself to crops and fences or other structures. Red Vine, Brunnichia ovata, is a perennial woody vine that regenerates new growth from woody rootstocks and climbs by its tendrils. It is a big problem for crops, especially soyabeans, in the Mississippi Delta, and also for gardeners when it spreads to the flower bed or vegetable plot. The vines’ extensive deep roots allow them to survive environmental extremes. Herbicides alone cannot provide complete control of the vines, so additional management tactics are needed.
Tendrils are organs used by some vines to help them climb, but little has been known about how they develop or support the vine. At the Southern Weed Science Research Unit in Stoneville, Mississippi, Christopher G. Meloche, a postdoctoral scientist, discovered two unique aspects of Red Vine tendrils: A compound that sticks the tendril to objects and a unique fibre cell that is involved in both coiling and final stiffening of the tendril. Red Vine tendrils begin growing out of the shoot straight, thin, and flexible. Meloche discovered that when the vine encounters something to climb, epidermal cells along the length of the tendril expand in response to touch by elongating in the direction of the stimulus. The tendrils as a whole respond by coiling around the object for support. Cells enriched with phenols break apart as the tendrils rub against the object. Then the phenols react with an enzyme, polyphenol oxidase (PPO), to produce a sticky cement that the tendrils use to adhere to the surface the vine is climbing.
This is the first time PPO has been implicated in generating an adhesive in a climbing plant. At the same time, it was discovered that a gelatinous fibre which has only been previously found in trees, is also at work in Red Vine. It was determined that the weed’s tendrils produce fibre cells enriched in lignin to radically increase the tendrils’ strength. Then the cells die, which leads to a dry, rigid coil structure that securely anchors the vine to the support. Photo: USDA
To read further gardening news from the News pages of the GardenMessenger web-site click here.
To join the GardenMessenger gardening community
To visit the GardenMessenger web-site
Directory of Gardening Blogs