Twisting upward on trees, plants, houses, and even lampposts, vines are a marvel of nature. Yet, beneath their enchanting appearance lies a parasitic behavior that poses significant threats to their hosts. By attaching to other life forms, vines block sunlight essential for growth and strangle their hosts, hindering the flow of water and nutrients. While these threats are well-documented, the mechanisms enabling vines to search, attach, and climb have remained elusive—until now.
An international team of scientists has decoded the genetic formula that empowers vines with their parasitic traits. This discovery highlights rapid elongation, directional movement, and the production of specialized contacting cells as key components. The team also identified a gene family responsible for engineering these capabilities.
Unlocking the Molecular Mechanisms
“Our research shows how molecular mechanisms are linked to plant movement—something we haven’t clearly understood,” explains Joyce Onyenedum, an assistant professor of environmental studies at New York University and a lead author of the study published in the journal New Phytologist. “Crucially, it gives us greater insight into these ropey parasites. They pose an ongoing menace to trees and other plants—among nature’s best tools for storing atmospheric carbon dioxide.”
It has been established that large tree branches bend through the production of fiber cells, known as “G-fibers,” which are specialized cells that contract. In a previous study, Onyenedum and her colleagues reported the presence of G-fibers within vine stems. However, the exact role of these cells remained unclear until now.
The Role of Hormones in Vines’ Growth
In their recent study, Onyenedum and her colleagues, including Lena Hunt, an NYU postdoctoral researcher, and Charles Anderson, a Penn State biologist, explored this question further. They studied common bean vines, which are globally cultivated and often seen in home gardens. Specifically, they examined the role of the hormone brassinosteroid, known for regulating plant developmental processes, including elongation.
The researchers compared growth in a normal bean vine to one engineered to produce an excess of this hormone. The excess hormones repressed the development of G-fiber cells, resulting in “lazy vines” that elongated too quickly and moved without direction.
“This timelapse video shows the two bean vines—the left plant has hormone levels typically found in vines and climbs normally; the right plant, by contrast, has an excess amount of hormones, creating an imbalance that stifles climbing,” explains Onyenedum.
Genetic Insights: The XTH5 Gene
The team also identified a candidate gene, XTH5, fundamental in plants’ structural growth and specifically expressed during G-fiber development. This discovery potentially identifies the key actor supporting the coiling and gripping of vines.
“Genes like XTH5 allow plants to remodel their cell walls, which are complex structures that provide strength and flexibility to plants. This study demonstrates that cell wall remodeling is a critical component of plant movements such as twining,” says Anderson.
“Our work shows that rapid elongation, directional movement, and the production of certain cells facilitate the maneuvering and eventual attachment of vines upon their host, thus unlocking the secrets to their behavior,” concludes Onyenedum.
Collaborative Efforts and Future Implications
The study also included contributions from researchers at the New York Botanical Garden, Brazil’s Federal University of Rio Grande do Sul, and the University of Michigan. This research was supported by a CAREER Award from the National Science Foundation.
The implications of this study extend beyond academic curiosity. Understanding the genetic and molecular basis of vines’ parasitic behavior could inform strategies to manage invasive vine species, protecting ecosystems and preserving biodiversity.
As scientists continue to explore the genetic underpinnings of plant behavior, this study represents a significant step forward in botanical research, potentially leading to innovative solutions for managing plant parasitism and enhancing agricultural practices worldwide.
