Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Potato blight pathogenicity explained by genome plasticity

04.07.2006
'Adjustable' genes are essential for inducing infection in potato plants

A team of researchers from Wageningen University report in this month's issue of Genome Research that they have identified a unique genetic fingerprint in the pathogen responsible for potato blight. Some strains of the pathogen possess multiple copies of a specific gene, while other strains possess only a single copy. Certain potato plants do not recognize strains of the pathogen with only the single gene copy, making them susceptible to infection. This is the first report of gene amplification in a non-bacterial organism that is associated with pathogenicity, and it provides insight into how plant pathogens tailor their genomes to adapt to their environments.

The potato late blight pathogen, known to scientists as Phytophthora infestans, is a fungus-like organism that was responsible for the Irish Potato Famine of the 1840s and continues to cause devastating agricultural losses worldwide today. Infected plants are characterized by dark lesions on the stems, leaves, and tubers; damage to the tuber surface allows other fungi and bacteria to enter and destroy the core, often resulting in a foul odor. P. infestans is related to approximately 65 other pathogens that cause similar damage to commercial crops as well as natural vegetation.

In the potato-Phytophthora system, the host-pathogen response has evolved in a highly specific way: resistance (R) genes from wild species, which are introduced into cultivated potato by breeding, are matched by avirulence (Avr) genes in Phytophthora. While many such gene matches are predicted, only a few have been confirmed by molecular and functional studies. Avr genes are thought to undergo rapid changes to evade detection by plants that possess R genes, which means that many strains of Phytophthora and potato are likely to be evolving at the present time.

"P. infestans is notorious for its ability to change in response to R genes," says Dr. Francine Govers, the principal investigator on the project. "These changes are probably facilitated by its underlying genomic plasticity. Field isolates of P. infestans are known to be genetically highly variable."

Govers, along with colleagues Rays Jiang, Rob Weide, and Peter van de Vondervoort, set out to identify the genetic basis for the virulence of specific Dutch P. infestans strains. The outcome of their efforts was the identification of single gene, called pi3.4, that was present as a single, full-length copy in both the virulent and avirulent strains. They also identified multiple copies of pi3.4 only in the avirulent strain – but, interestingly, these copies represented only part of the pi3.4 gene.

The authors speculate that the partial gene copies could function as a source of modules for generating new genes. These new genes could be produced by unequal crossing-over, or exchange of genetic material, during development. The partial copies may also serve as alternative protein-coding units, which allow the pathogen to produce a diverse array of proteins and, consequently, to adapt to its environment.

"Surprisingly, the pi3.4 gene does not code for an effector – a small protein that elicits a defense response in plants," adds Govers. "Effectors are quite common in fungal and bacterial plant pathogens, including Phytophthora. But in our case, the gene appears to produce a large regulatory protein that exerts its effect by regulating the expression of other genes, possibly effector genes."

While the exact mechanism by which these partial gene copies function as a source of modular diversity remains to be resolved, this study highlights the importance of genome plasticity in evolution. Understanding genome plasticity as a mechanism for environmental response and ecological adaptation in pathogenic organisms has important implications. "The efforts of plant breeders to obtain resistant varieties by introducing R genes, either by classical breeding or by genetic modification, may be a waste of time and resources when the genome dynamics of the pathogen population is not understood," says Govers. "Monitoring field populations of plant pathogens at the genome level will be instrumental for predicting the durability of R genes in crop plants."

Maria Smit | EurekAlert!
Further information:
http://www.cshl.edu
http://www.genome.org

More articles from Life Sciences:

nachricht Programming cells with computer-like logic
27.07.2017 | Wyss Institute for Biologically Inspired Engineering at Harvard

nachricht Identified the component that allows a lethal bacteria to spread resistance to antibiotics
27.07.2017 | Institute for Research in Biomedicine (IRB Barcelona)

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Physicists Design Ultrafocused Pulses

Physicists working with researcher Oriol Romero-Isart devised a new simple scheme to theoretically generate arbitrarily short and focused electromagnetic fields. This new tool could be used for precise sensing and in microscopy.

Microwaves, heat radiation, light and X-radiation are examples for electromagnetic waves. Many applications require to focus the electromagnetic fields to...

Im Focus: Carbon Nanotubes Turn Electrical Current into Light-emitting Quasi-particles

Strong light-matter coupling in these semiconducting tubes may hold the key to electrically pumped lasers

Light-matter quasi-particles can be generated electrically in semiconducting carbon nanotubes. Material scientists and physicists from Heidelberg University...

Im Focus: Flexible proximity sensor creates smart surfaces

Fraunhofer IPA has developed a proximity sensor made from silicone and carbon nanotubes (CNT) which detects objects and determines their position. The materials and printing process used mean that the sensor is extremely flexible, economical and can be used for large surfaces. Industry and research partners can use and further develop this innovation straight away.

At first glance, the proximity sensor appears to be nothing special: a thin, elastic layer of silicone onto which black square surfaces are printed, but these...

Im Focus: 3-D scanning with water

3-D shape acquisition using water displacement as the shape sensor for the reconstruction of complex objects

A global team of computer scientists and engineers have developed an innovative technique that more completely reconstructs challenging 3D objects. An ancient...

Im Focus: Manipulating Electron Spins Without Loss of Information

Physicists have developed a new technique that uses electrical voltages to control the electron spin on a chip. The newly-developed method provides protection from spin decay, meaning that the contained information can be maintained and transmitted over comparatively large distances, as has been demonstrated by a team from the University of Basel’s Department of Physics and the Swiss Nanoscience Institute. The results have been published in Physical Review X.

For several years, researchers have been trying to use the spin of an electron to store and transmit information. The spin of each electron is always coupled...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Clash of Realities 2017: Registration now open. International Conference at TH Köln

26.07.2017 | Event News

Closing the Sustainability Circle: Protection of Food with Biobased Materials

21.07.2017 | Event News

»We are bringing Additive Manufacturing to SMEs«

19.07.2017 | Event News

 
Latest News

Programming cells with computer-like logic

27.07.2017 | Life Sciences

Identified the component that allows a lethal bacteria to spread resistance to antibiotics

27.07.2017 | Life Sciences

Malaria Already Endemic in the Mediterranean by the Roman Period

27.07.2017 | Health and Medicine

VideoLinks
B2B-VideoLinks
More VideoLinks >>>