A parasitic dodder wraps around a sesame plant
A dodder parasitizes a sesame plant, stealing nutrients and genetic material from its host.
Photo Credit: Osaka Metropolitan University
Scientific Frontline: Extended "At a Glance" Summary: Horizontal Gene Transfer in Parasitic Plants
The Core Concept: Parasitic plants, such as dodders, acquire and permanently integrate functional foreign genes from their host plants through horizontal gene transfer (HGT). Instead of merely preserving these stolen genes, the parasites structurally remodel them over millions of years while retaining their original biological functions.
Key Distinction/Mechanism: Unlike standard vertical inheritance from parent to offspring, HGT allows genetic material to cross species boundaries. In the dodder lineage, a stolen host gene (CYP81Q) was modified by transposable elements, or "jumping DNA," that inserted into the gene to form a new intron, yet the remodeled gene continued to produce a functional enzyme.
Major Frameworks/Components:
- Horizontal Gene Transfer (HGT): The lateral movement of genetic material between unrelated organisms, a process common in bacteria but now shown to be a significant evolutionary driver in parasitic plants.
- Transposable Elements: Sequences of mobile DNA that insert into the genome, contributing to the structural remodeling and adaptation of newly acquired genes.
- Intron Formation: The process by which inserted parasite DNA integrates into a foreign gene, becoming a noncoding section (intron) that is spliced out of RNA before the genetic instructions are used to synthesize a protein.
- CYP81Q Gene: A cytochrome P450 gene responsible for producing sesamin, an antioxidant lignan compound, which dodders gained the autonomous ability to synthesize after stealing the gene.
Branch of Science: Plant Genetics, Evolutionary Biology, Molecular Biology, and Plant Physiology.
Future Application: Understanding how complex traits and functional genes are horizontally transferred, structurally remodeled, and stabilized in parasitic plants could inform advanced bioengineering strategies, transgenic crop development, and new methods for conferring stress tolerance in agriculture.
Why It Matters: This discovery proves that HGT in plants is not an evolutionary dead end; parasites can completely integrate and modify foreign genetic material to acquire advantageous traits, fundamentally challenging traditional views of plant evolution and genetic inheritance.
Many plant species parasitize other plants by latching on and extracting the nutrients their hosts need to survive. Sometimes, however, plants steal more than nutrients; they acquire genes.
A recent study demonstrates how one such “stolen” gene was not simply preserved after entering the genome of the parasitic dodder (Cuscuta spp.). Instead, the parasite remodeled the gene over millions of years while maintaining its original function.
This gene acquisition occurs through a process known as horizontal gene transfer (HGT). Unlike ordinary inheritance, in which genes pass from parent to offspring, HGT allows genetic material to move between unrelated organisms.
A research team led by Professor Koh Aoki of the Graduate School of Agriculture at Osaka Metropolitan University investigated what happens to these foreign genes after they enter the parasitic plant. Working with researchers from Suntory Global Innovation Center Ltd., the National Institute for Basic Biology, and other institutions, the team traced the evolutionary history of the CYP81Q gene.
They found evidence that CYP81Q originally belonged to another flowering plant in the order Lamiales—which includes many medicinal and culinary herbs—before being transferred to the dodder lineage in the distant past.
The gene conferred a useful trait to dodders, as CYP81Q is involved in producing sesamin, a lignan compound with antioxidant properties. After acquiring the gene, dodders gained the ability to produce sesamin themselves.
Over time, the foreign gene was altered within the dodder genome by pieces of transposable elements called “jumping DNA,” which inserted dodder DNA into CYP81Q. One of these inserted sequences eventually became part of a newly formed intron, a section of a gene removed from its RNA before the genetic instructions are used to synthesize a protein.
Despite undergoing these changes, the gene remained active. The remodeled CYP81Q still produced a functional enzyme capable of synthesizing sesamin.
“This demonstrated that the gene had retained its biological function despite substantial structural changes,” Professor Aoki summarized.
The finding suggests that HGT is not necessarily the end of the gene's evolutionary story; instead, the gene can continue to evolve inside the parasite, becoming structurally integrated into its new surroundings while retaining its original function.
“Usually, HGT is a process associated with bacteria,” Professor Aoki said. “Our findings are further evidence that it is found in plants, too.”
For parasitic plants, this process may be especially important. Their direct connections with other plants create unusual opportunities for genes to cross species boundaries. Once transferred, those genes may become raw material for further evolutionary change.
The story of CYP81Q goes beyond dodders simply “stealing” a useful gene; it illustrates the plant making the borrowed genetic material its own.
Funding: This work was supported in part by Grants-in-Aid for Scientific Research (A) (18H03950 and 19H00944, Japan Society for the Promotion of Science to K.A.), a Grant-in-Aid for Transformative Research Areas (25A305, Japan Society for the Promotion of Science to K.A.), a research grant from the Ohsumi Frontier Science Foundation (to K.A.), and a Grant-in-Aid for JSPS Fellows (19J14848, Japan Society for the Promotion of Science to K.S.).
Published in journal: Plant Physiology
Authors: Eiichiro Ono, Kohki Shimizu, Jun Murata, Tenta Segawa, Akira Shiraishi, Ryusuke Yokoyama, Hiromi Toyonaga, Masaki Takagawa, Manabu Horikawa, Atsushi Hoshino, and Koh Aoki
Source/Credit: Osaka Metropolitan University
Edited by: Scientific Frontline
Reference Number: bot082726_01
