A Selfish Gene: How a single gene threatens wheat

Play Video

$40,000

Prizes

4,177

Views

1. Please give a brief summary of your work.

Crop plants, like us, have pathogens that cause disease. These pathogens have a single goal; consume plant biomass to grow and reproduce, reducing yields. Yield losses in staple crops have far reaching consequences, whereby shortages lead to economic loss, increased food prices and hunger.


A live plant has ways to protect itself from being eaten, which pathogens must work around. How do they do this? Some produce toxins that kill the plant and allow it to feed off the dead tissue. My work focuses on one these toxins, called ToxA. ToxA is unique because it specialises in damaging wheat leaves. Prior to our paper, ToxA was thought to be produced by only two pathogenic fungal species, both of which cause globally important diseases of wheat. Surprisingly, we discovered ToxA in a third fungal species. This new species is a severe pathogen of wheat in food insecure regions of Central Asia. 

2. Describe your approach and broader findings.

The problem with agriculture

 

A typical wheat field is a monoculture, composed of plants that are clones. These clones all grow at the same rate and set seed at the same time, which makes the decision on when to harvest easy. This convenience comes at a high cost. The uniformity of the plants make the entire field vulnerable and a field epidemic rapidly spreads its disease to neighbouring fields. Pathogens evolve mechanisms to attack plants and acquire nutrients from them. Once established, these mechanisms are easily shared within a pathogen species through sexual recombination. A more interesting form of evolution occurs when pathogens exchange DNA between species; a biological process known as Horizontal Gene Transfer (HGT). We observe HGT events by detecting genes or sequences of DNA that are near identical between distantly related species. To an untrained eye, it may appear that these DNA fragments are “copy-and-pasting” themselves between organisms. My work investigates one of these cases, where a single horizontally transferred gene that confers extreme virulence towards wheat, is shared between three fungal species.

 

ToxA, a selfish gene that kills wheat

 

I utilise whole genome sequencing to understand how fungal pathogens interact with plants. We have known for some time that the wheat toxin ToxA is produced by two fungal wheat pathogens, Parastagonospora nodorum and Pyrenophora tritici-repentis. These pathogens are hypothesized to have shared ToxA and some surrounding DNA with each other via HGT, resulting in an 11 thousand base sequence that is near identical between the two species. In our study, genome sequencing unexpectedly revealed the presence of ToxA in the genome of the fungal wheat and barley pathogen Bipolaris sorokiniana. Remarkably, ToxA found in our genome assembly has the exact same 11 thousand base fragment that is found in the other two species, with near identical DNA sequence. The high identity shared between these three species indicates that this HGT event must be extremely recent, perhaps occurring within this century. It also demonstrates the value of ToxA itself, which is important enough to be shared between three separate wheat diseases.

 

We know that ToxA is responsible for necrosis (cell death) on the wheat leaf during infection. It does this in a very specific way by acting in a ‘gene-for-gene’ relationship with a wheat susceptibility gene, Tsn1. If both genes are present, ToxA in the fungus and Tsn1 in wheat, the infected leaf dies. If either gene is absent, then there are no ToxA related symptoms. We tested whether our B. sorokiniana isolates carrying ToxA had higher disease symptoms on wheat varieties that contain Tsn1. Our results unequivocally showed that a B. sorokiniana isolate carrying ToxA has increased leaf necrosis on Tsn1 wheat in comparison to a non-Tsn1 wheat variety. This is important for two reasons: (1) It shows that ToxA plays a critical role in the disease caused by B. sorokiniana (2) There are other unknown virulence factors in B. sorokiniana that damage wheat in the absence of ToxA.

3. What is the wider contribution, or impact, to your scientific field(s)?

ToxA is a threat to global wheat yields

 

This work further cements Horizontal Gene Transfer (HGT) as a tool through which fungal pathogens can share strategies to exploit host vulnerabilities. HGT is of course not limited to plant pathogens; we know that it plays a central role in the evolution of multi-drug resistant bacteria in hospitals, where we now face bacteria that are resistant to all known antibiotics. In the case of ToxA, we have shown that an identical protein facilitates disease on wheat for three separate fungal diseases. These three diseases are all prominent throughout the wheat-growing world, meaning that ToxA is a global threat to wheat yield. Our work highlights the wide-reaching impact that HGT can have in plant pathogen interactions and the threat it poses to food security.

 

Field based application of our work

 

Our work is also immediately applicable to field based control of pathogens carrying ToxA. This is because ToxA has an Achilles heel: it requires the non-essential wheat gene, Tsn1, to induce leaf necrosis. This gene can be selectively bred out of commercial wheat cultivars with no known harm to the plant. Wheat cultivars that do not carry Tsn1 are totally resistant to ToxA and its effects. This strategy was used successfully in Australia to limit the effects of ToxA and increase wheat yields. This knowledge could be critical for farmers and breeders in India and other regions of Central Asia, where B. sorokiniana is a major disease. Removal of Tsn1 from these cultivars could immediately improve yields in regions with poor food security. 

4. Are there any potential ideas you would like to explore to take this research further?

Now that we have found ToxA in three different fungal species, there are several remaining questions.

1) Where did ToxA come from?

2) Why is it exceptionally mobile?

3) What is the vehicle for DNA movement between these fungi?

4) Can we prevent ToxA from moving further?

Future work will use whole genome resequencing with cutting-edge long-read technology to answer these questions.

 

We know from our short-read data that the genomic region surrounding ToxA contains repetitive DNA. This makes it difficult to analyse historical movement of ToxA. Using the Oxford Nanopore MinIon, we will be able to sequence through these repetitive regions and identify the chromosomes that contain ToxA in each species. In doing so we will, for the first time, be able to describe the DNA elements that make ToxA mobile. Once we understand this, we can address the problem of how to limit future movement into other plant pathogens.

 

Further, it is likely that there are more copies of ToxA in other organisms that we have yet to sequence. The obvious place to start looking is where the gene has its strongest effect; the genomes of other pathogens associated with wheat. We will seek to identify other organisms carrying ToxA by generating new long-read de novo assemblies of un-sequenced wheat pathogens. While this is a risky search, ToxA has proved itself resilient and valuable to these pathogens. Finding its origin is important to understanding how and why wheat became its target.

5. Please share a link for researchers to access a relevant publication, data-set, or thesis.

Comments

6
dfife dfife
about 1 year ago

Sounds like fascinating research!

Bruce McDonald
about 1 year ago

Great work Megan!

Patrick Brunner
about 1 year ago

Nice presentation, Megan!
May I ask some random questions ..... ?

Yit Heng Chooi
about 1 year ago

Go Megan!

hzxhzx hzxhzx
2 months ago

adidas outlet


adidas originals


nike shox


nike air max


vans outlet


givenchy handbags


ray ban sunglasses


balenciaga sandals


christian louboutin


nike kyrie 3


kate spade outlet


roshe run


stephen curry shoes


nike air max 90


ralph lauren uk


oakley sunglasses


true religion


hermes bags


nike lunarglide


timberland outlet


mishka clothing


undefeated clothing


polo outlet


louboutin


converse outlet


asics


louis vuitton outlet


coach outlet


oakley sunglasses


ferragamo


nike tn


michael kors outlet


louis vuitton outlet


nike trainers


vibram fivefingers


mont blanc pens


adidas jeremy scott


pandora jewelry


adidas outlet


flops


nike free


swarovski jewelry


manchester united jersey


coach outlet store online


jordan shoes


birkenstock outlet


nike huarache


nhl jerseys


ferragamo


michael kors outlet


coach outlet


coach outlet


mlb jerseys


manolo blahnik


lebron 15


nike roshe


supra shoes


cheap jerseys


bvlgari jewelry


adidas outlet


coach outlet


cheap jerseys


dior handbags


nike outlet store online


adidas yeezy


jordan shoes


red bottom shoes


coach wallets


adidas ultra boost


kevin durant shoes


ray ban sunglasses


polo ralph lauren


michaelkors outlet


ralph lauren


jordan 5


beats by dre


michael kors


barcelona jersey


mbt


timberland boots


coach handbags


red bottom shoes


louis vuitton


jordan 8


ralph lauren


michael kors handbags


louis vuitton outlet


mulberry


michael kors outlet


nike air max


stussy clothing


marc jacobs


longchamp


baseball jerseys


ray ban sunglasses


nike outlet


beats by dre


adidas yeezy


toms outlet


hermes


asics


dolce and gabbana


coach outlet online


wholesale snapback hats


ray ban sunglasses


birkenstock outlet online


gucci outlet


adidas nmd


jordan 1


new balance


ray bans


jordan 6


nike free


oakley sunglasses


mcm backpack


air jordan


replica rolex watches


nike dunks


flip-flops


cheap jordans


louis vuitton handbags


kate spade outlet


birkenstock sandals


louis vuitton outlet


michael kors


hollister outlet


adidas wings


balenciaga


jordan


ralph lauren


adidas


adidas nmd


yeezy shoes


jordans


herve leger dresses


ray ban sunglasses


new balance sandals


pandora jewelry


louboutin


louis vuitton


supreme new york


fingerlings monkey


mont blanc


puma fenty sandals


nike shoes


louis vuitton


polo ralph


ralph lauren


nike air max 1


cheap rolex watches


chicago blackhawks jersey


coach factory outlet


off-white


red bottom shoes


polo shirts


burberry outlet


coach outlet online


hermes belt


jordans


ray ban


flops


salvatore ferragamo


cartier bracelet


michael kors outlet


nfl jerseys


oakley sunglasses


longchamp outlet


oakley sunglasses


coach outlet


vans shoes


nike presto


nfl jerseys


harden vol 2


light up shoes


oakley sunglasses


true religion outlet


longchamp


burberry sale


jordan 3


rolex watches


coach outlet


louis vuitton handbags


air jordan


mbt


harden vol 1


kate spade handbags


toms shoes


nike blazer shoes


polo ralph


nike air force 1


oakley


ralph lauren outlet


timberland


nike mercurial


michael kors


kate spade


breitling watches


fitflops


nike huarache


michael kors outlet


nike free


tory burch outlet


dansko


gucci slides


kate spade outlet


nike sb


ralph lauren


nike huarache


jordans


nike air max 95


nike shoes


nfl jerseys


ray ban sunglasses


shoe carnival


jordan xx9


louis vuitton


nike shoes


michael kors handbags


louis vuitton outlet


mac cosmetics


hermes kelly bag


jordan shoes


jordan 12


supreme


prada outlet


off-white clothing


pandora jewelry


superdry clothing


michael kors outlet


oakley sunglasses


tag heuer watches


giuseppe zanotti


van cleef & arpels jewelry


jordan shoes


mont blanc pens


nike air max 97


louis vuitton handbags


nike blazer


kobe 11


replica watches


baseball bats


kate spade outlet


michael kors outlet


nike tennis


pandora outlet


nike air max


cheap nhl jerseys


longchamp outlet


michael kors


coach outlet


louis vuitton


michael kors


converse shoes


nba jerseys


supreme


running shoes


michael kors


coach outlet


true religion


coach outlet


birkenstock sandals


fitflops


louis vuitton


coach outlet


nike air max 2018


fila shoes


puma slides


under armour outlet


birkenstock outlet


suicoke sandals


ray ban


soccer jerseys


ralph lauren


burberry scarves


cheap oakley sunglasses


prada


malone souliers


cheap jerseys


jordan


tory burch outlet


bottega


nike outlet store


jimmy choo outlet


jordan 11


adidas flip flops


air jordan pas cher


timberland


polo ralph lauren


burberry outlet


louis vuitton


sac longchamp


coach factory outlet


nike factory outlet


nike flip-flops


valentino


prada


stuart weitzman


longchamp


michael kors outlet


wedding shoes


louis vuitton


hermes outlet


pandora charms


true religion outlet


nike shoes for women


oakley sunglasses


supreme clothing


breguet watches


louis vuitton outlet


air max


adidas stan smith


nike epic react flyknit


juicy couture outlet


true religion jeans


ralph lauren outlet


bcbg


nike air max plus


tory burch outlet


adidas football boots


ray ban sunglasses


belstaff outlet


tory burch


michael kors outlet


jordan shoes


balenciaga triple s


michael kors


pandora charms


mlb jerseys


yeezy 500


coach factory outlet


nike cortez


coach outlet


converse


nike store


y-3 shoes


basketball shoes


ray ban sunglasses


flip flops


adidas superstar


louis vuitton


polo outlet


cheap ray ban sunglasses


pandora jewelry


timberland


burberry outlet


fitflops


nike air max 270


nike outlet


nike air force 1


ray ban sunglasses


nike air


nike revolution


celine


coach outlet


mlb jerseys


tod's shoes


coach outlet


cheap nfl jerseys


jordans


oakley sunglasses


alexander mcqueen


adidas outlet store


audemars piguet


mizuno


fitflops


adidas slides


air jordan


pandora jewelry


coach bags


nike free run


miu miu handbags


polo ralph lauren


true religion jeans


nike air max 2017


swarovski


michael kors handbags


nike air max


pandora charms


air max


jordan 4


rolex watches


louboutin


ray ban


ralph lauren


prada outlet


jordan


rolex watches


links of london


swarovski


new balance shoes


adidas shoes


nike air max


louboutin shoes


christian louboutin


louboutin


christian louboutin


christian louboutin outlet


coach outlet


coach outlet online


michael kors outlet store


kobe 12 shoes


nfl jerseys wholesale


timberland boots

hzx20180516

yaoxuemei yaoxuemei
14 days ago

adidas yeezy shoes


coach outlet


nike kyrie 3


pandora outlet


ray ban sunglasses


coach outlet canada


cheap nfl jerseys


michael kors outlet


polo outlet


michael kors outlet


oakley sunglasses wholesale


pandora jewelry


ralph lauren outlet


cheap mlb jerseys


christian louboutin outlet


ralph lauren outlet


coach outlet


michael kors outlet


ralph lauren outlet


polo ralph lauren


gucci outlet


oakley sunglasses wholesale


fitflops sale clearance


canada goose outlet


ray ban sunglasse


fred perry polo shirts


christian louboutin shoes


coach outlet


canada goose outlet


polo outlet


polo outlet


tory burch outlet


fred perry outlet


fitflops sale clearance


coach outlet


coach outlet


michael kors outlet


off white clothing


michael kors outlet


oakley sunglasses wholesale


cheap ray bans sunglasses


canada goose outlet


polo outlet


canada goose jackets


nike air max


ralph lauren polo shirts


mcm handbags


giuseppe zanotti outlet


michael kors outlet


cheap jordans


michael kors outlet


michael kors outlet


canada goose outlet


adidas yeezy


true religion jeans


fred perry polo


coach outlet


coach outlet


pandora jewelry


pandora jewelry


uggs outlet


canada goose outlet


louboutin shoes


birkenstock shoes


canada goose outlet


oakley sunglasses


true religion jeans


ugg outlet


adidas outlet


coach outlet


kate spade handbags


mlb jerseys wholesale


christian louboutin outlet


coach outlet online


cheap nfl jerseys


michael kors outlet


ugg outlet


moncler outlet


michael kors outlet clearance


true religion jeans


christian louboutin outlet


coach outlet


true religion outlet


christian louboutin outlet


nike outlet


michael kors uk


adidas nmd


kate spade outlet


coach outlet


kate spade outlet


pandora jewelry


tory burch outlet


adidas yeezy


uggs outlet


ugg outlet


nhl jerseys


supreme uk


mont blanc pens


pandora outlet


nike shoes


coach outlet


rolex watches


michael kors handbags


nfl jerseys


kate spade outlet


superdry clothing


ray ban outlet


coach factory outlet


mbt shoes


coach outlet online


pandora outlet


nfl jerseys wholesale


coach outlet online


polo ralph lauren


adidas superstar shoes


coach outlet


uggs outlet


coach outlet


polo shirts


kate spade outlet


oakley sunglasses wholesale


ferragamo outlet


clarks shoes


michael kors outlet


coach outlet


christian louboutin outlet


coach factory outlet


pandora outlet


nike outlet


coach outlet


nfl jerseys wholesale


polo outlet


cheap nfl jerseys


cheap jordans


tory burch outlet


nba jersey


kate spade outlet


ray ban sunglasses


christian louboutin outlet


coach outlet store online


yaoxuemei20180709

Image1495085925?1495085925

I completed my PhD in population genetics at the prestigious ETH Zurich in 2012, a top 10 world University. My work during my Phd led to a successful fellowship application, which brought me to the...

Recent Voters