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Former defense strategy continues to protect plants against pathogens

Former defense strategy continues to protect plants against pathogens

A Marchantia liver, where defense genes and purple pigment production have been activated only in specific areas. Credit: Philip Carella

Scientists at the University of Cambridge have discovered striking similarities in how two distant plants defend themselves against pathogens despite the separation of their common ancestor more than 400 million years ago.

Researchers at the Sainsbury Laboratory at the University of Cambridge have compared the relationship between two distant plants: a common liverwort (Marchantia polymorpha) and a flowering plant, wild tobacco (Nicotiana benthamiana– to defend against an aggressive pathogen (Phytophthora palmivora). This is the first time that such a comparison is undertaken. By studying how these far-away plants – which separated from their common ancestor about 400 million years ago – respond to infections with pathogens, the research team discovered a series of germ-sensitive gene families that trace back to the early evolution of terrestrial plants.

Our current understanding of how plants manage to defend against disease-causing pathogens comes mainly from the study of economically important crops and a small number of closely related flowering plant models. Extremely distant relatives, such as non-flowering liverworts that look like some of the earliest terrestrial plants, are often overlooked. As a result, little was known about how these plants defend against pathogens or the evolution of plant defense strategies.

Posted in Current biology Today, the identification of these genes conserved during evolution sheds new light on the strategies likely critical for the expansion of plants on the mainland.

"We have shown that molecular responses to infections caused by pathogens typical of modern flowering plants are common to far-flung terrestrial plants and may be older than we previously thought," says Dr. Sebastian Schornack, who led the research team that undertook the research. study. "Despite fluctuating environmental pressures over a broad period of evolution, these conserved genes have retained their ability to provide protection against plant pathogens, including in field crops."

Dr. Anna Gogleva, an expert in bioinformatics, has identified a subset of corresponding genes (single copy orthologues) in the hepatic and wild tobacco and analyzed their level of activity during the course of the year. ;infection. A number of different genes were activated in both plants, but a set of metabolic genes involved in the biosynthesis of phenylpropanoids (flavonoids) were strongly activated in response to the infection.

Former defense strategy continues to protect plants against pathogens

Microscopic image of a hepatic part of which accumulated purple pigment (left). The pathogen can be detected as a red fluorescence and it sporulates only in green tissue and does not accumulate well in purple tissue with activated defense (right). Credit: Philip Carella

These gene families are often associated with the stress response in flowering plants, providing increased protection against biotic or abiotic stresses caused by chewing insects, pathogens, and nutrient or light stress. However, this was the first time that these genes were functionally related to the pathogen defense strategies in liverworts.

"The zoospores of pathogens germinate on the surface of liverworts and eventually colonize liver tissues, but in some areas we have observed an accumulation of purple / red pigment in liver tissues where the agent Pathogen was seldom detected, "says Dr. Philip Carella, lead author. of the study.

"We produced horticulturists with patterns of mosaic pigments – resembling military camouflage lattices – that allowed us to compare the resistance of pathogens in the pigmented and unpigmented areas of the same plant and that the pigment conferred certain resistance to infections by pathogens. "

The enormous diversity of traits and species we see today in modern plants reflects the millions of years of evolution that have allowed plants to survive in dynamic environments. and contrasted throughout the world.

"The conflict between organisms can be a very powerful selective pressure guiding their evolutionary trajectory," says Dr. Schornack. "The genes involved in the fight against specific pathogens can evolve rapidly, both in plants and animals, but we have also found these largely conserved genes that respond to infection by a plant pathogen. very distant, suggesting that terrestrial plants have retained a probable old pathogen.a deterrent strategy far too useful to lose.

"Fossil evidence shows that plants have had close interactions with microbial lifeforms throughout their evolutionary history.Our research has uncovered a common set of shared pathogen-sensitive genes in early-divergent terrestrial plants." and younger and evolving flowering plants, all of which are comparative studies of other distant terrestrial plants and their predecessors on aquatic algae should reveal even more information about the evolution and role of of these families of vital genes. "

Research shows that early terrestrial plants were parasitized by microbes

More information:
Philip Carella, Anna Gogleva, David John Hoey, Anthony John Bridgen, Sara Christina Stolze, Hirofumi Nakagami and Sebastian Schornack. "The conserved biochemical defenses underlie host responses to Oomycete infection in a line of early divergent terrestrial plants." Current biology (2019). DOI: 10.1016 / j.cub.2019.05.078

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University of Cambridge

Former defense strategy continues to protect plants against pathogens (July 11, 2019)
recovered on July 11, 2019
from https://phys.org/news/2019-07-ancient-defense-strategy-pathogens.html

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