Studies towards late blight control in potato
(2013)- Abstract
- Abstract
The oomycete Phytophthora infestans, which causes the devastating late blight disease of potato, is notorious for
developing resistance to conventional control strategies (fungicide application and resistance breeding by
introgression of R gene). To increase our tool box of disease management strategies available to combat P.
infestans, there is a need to explore several new approaches that can lead to more durable solutions to control late
blight disease. Using the potato-P. infestans pathosystem, different approaches were used in this thesis with an aim
to enhance potato defence and find new resistance sources to P. infestans. In the first approach, exogenous
... (More) - Abstract
The oomycete Phytophthora infestans, which causes the devastating late blight disease of potato, is notorious for
developing resistance to conventional control strategies (fungicide application and resistance breeding by
introgression of R gene). To increase our tool box of disease management strategies available to combat P.
infestans, there is a need to explore several new approaches that can lead to more durable solutions to control late
blight disease. Using the potato-P. infestans pathosystem, different approaches were used in this thesis with an aim
to enhance potato defence and find new resistance sources to P. infestans. In the first approach, exogenous
application of a new natural agent, sugar beet extract (SBE), resulted in significant reduction of the size of the
infection lesions. The pattern was similar to that seen with application of a known defence-inducing compound, β-
aminobutyric acid (BABA). SBE triggered pathogenesis-related protein production with no toxic effect on pathogen
growth from SBE was noted, which suggests that the protection conferred by SBE is via induced resistance. BABA
is a non-protein amino acid that was shown to induce resistance in different plant species and against various
pathogens. However, its mechanism of induced resistance (IR) activation in potato to P.infestans is unclear. Thus, in
the second approach, a proteomic and transcriptomic study was conducted in an attempt to unravel the mechanism
of BABA-IR in potato. It became clear from our study that BABA results in direct activation of several hormonerelated
pathways and defence-related proteins. In the third approach, a constitutively activated defence was
discovered in one Phytophthora-resistant potato clone (out of two investigated), which could be an interesting
starting material in resistance breeding. In the fourth approach, engineering potato plants by in planta expression of
pathogen-associated molecular patterns (Pep13 and flg22) resulted in significant reduction of late blight severity,
which could be a suitable strategy to alleviate the severity of plant diseases. An integrated pest management
approach, including reduction of the use of the fungicides, is one of the recommendations of the recent EU directive.
Thus, it is anticipated that combining induced resistance principle and/or a properly designed transgenic approach
with conventional control strategies can reduce fungicide inputs and provide a more efficient and sustainable
solution for late blight problem. (Less) - Abstract (Swedish)
- Popular Abstract in English
Plant diseases are directly associated with food security because they result in severe
reduction of plant yield and thus they add to the scarcity of foods in the world, which can
lead to negative repercussions on humankind. Late blight disease that severely hit Ireland in
1840s, which was caused by Phytophthora infestans and is mentioned in the historical
records as the Irish Famine, can be a testimony of the involvement of plant pathogens in
human tragedies and shaping the history of humankind. Through constant research and
discoveries, it became clear that control of plant diseases could be done by breeding resistant
varieties and... (More) - Popular Abstract in English
Plant diseases are directly associated with food security because they result in severe
reduction of plant yield and thus they add to the scarcity of foods in the world, which can
lead to negative repercussions on humankind. Late blight disease that severely hit Ireland in
1840s, which was caused by Phytophthora infestans and is mentioned in the historical
records as the Irish Famine, can be a testimony of the involvement of plant pathogens in
human tragedies and shaping the history of humankind. Through constant research and
discoveries, it became clear that control of plant diseases could be done by breeding resistant
varieties and by using agrochemicals, which led to enhanced plant protection and increased
yields. Plant pathogens became increasingly resistant to these conventional control strategies
due to their excessive and wide-spread use in different parts of the world. Taking P.infestans
as an example, recent research conducted in the areas of genome sequencing, pathogenicity,
and genetics revealed tactics used by this this devastating pathogen to defeat resistance
conferred by the resistant varieties and fungicides. It is now evident that this pathogen
contains several classes of transposons (jumping DNA elements) that can accelerate
pathogen evolution and also several types of pathogen proteins (named effectors) that affect
the host. Effectors can be viewed as a double-edged sword: they can either result in
resistance in plants that can have the required recognition system to recognize these
effectors so that the plants can be immunized against these pathogen isolates, or they can
result in disease initiation by suppression of the plant recognition system. Because of these
issues combined with the hazards that fungicides can have on health and environment, new
approaches to control plant diseases are now required. Plants are known to have their own
immune system and they induce various defence responses when they encounter different
stresses like pathogens. It was found, for example, that synthetic chemicals like analogues of
plant hormones or the non essential amino acid β-aminobutyric acid (BABA), when applied
to plants can result in enhanced resistance to pathogens because these chemicals, which are
called plant defence activators, activated plant defence responses and made the plant on the
alert against future plant infection in a more efficient way than the non-treated plants. This is
known as induced resistance and it is an interesting area of research with potential
application in modern agriculture. However, the prices of these chemicals can be prohibitive
for farmers. It stands to reason that natural and cheap agents that can have defence-inducing
ability can be an interesting alternative. I have found that sugar beet extract (SBE), extracted
through a simple extraction method from a large-scale plant waste product, could induce
defence in potato to P. infestans in a similar way in which the synthetic chemical BABA
does. The agent reduced the infection lesions on the plants and reduced the total number of
26
infectious propagules (sporangia) in plants, which indicates a good potential for its possible
use in organic farming or in general plant disease control strategies. The need to understand
the mechanism of plant defence activators is important to study in order to effectively apply
these agents in large-scale application in agriculture. BABA is a well-known defence
inducing agent, thus its mechanism of induced resistance was studied in potato after BABA
treatment to understand why potato plants become more resistant to P. infestans. In order to
study the changes after BABA treatment, detailed proteomic and transcriptomic study was
conducted for this purpose, which found that direct activation of hormone-related pathways
and defence-related proteins was involved in the induced resistance. In another project, it
was found that a Phytophthora-resistant potato clone from potato breeding program
displayed constitutive activation of plant defences without any pathogen stress, which can be
a good basis for future breeding efforts. Resistance can be engineered by genetically
modifying plants. During plant-microbe interactions, some molecules are released from
pathogens, which are termed pathogen-associated molecular patterns (PAMPs) and which
are recognized by specific plant receptors to activate plant defences. I have found that by
expressing two PAMPs in potato plants, one from bacteria (flg22) and the other one from
Phytophthora spp. (pep13), significant reduction of late blight severity was achieved, which
can be an interesting strategy to control late blight disease. Moreover, it is possible to
combine the transgenic approach or the induced resistance breeding with the conventional
control strategies to provide a more efficient and durable solution for the late blight problem. (Less)
Please use this url to cite or link to this publication:
https://lup.lub.lu.se/record/3559283
- author
- Moushib, Laith LU
- supervisor
- opponent
-
- Jørgensen, Hans, University of Copenhagen, Molecular Plant Biology
- organization
- publishing date
- 2013
- type
- Thesis
- publication status
- published
- subject
- keywords
- Oomycetes, plant induced resistance, sustainable agriculture, plant defence activators, plant innate immunity, potato, late blight
- publisher
- Department of Biology, Lund University
- defense location
- Crafoordsalen at Alnarp SLU
- defense date
- 2013-03-27 09:12:00
- language
- English
- LU publication?
- yes
- additional info
- The information about affiliations in this record was updated in December 2015. The record was previously connected to the following departments: Department of Cell and Organism Biology (Closed 2011.) (011002100), Molecular Cell Biology (432112241)
- id
- 2c5190cc-36df-4dfa-9d28-9e70599dba49 (old id 3559283)
- date added to LUP
- 2016-04-04 11:06:13
- date last changed
- 2018-11-21 21:02:41
@phdthesis{2c5190cc-36df-4dfa-9d28-9e70599dba49, abstract = {{Abstract<br/><br> The oomycete Phytophthora infestans, which causes the devastating late blight disease of potato, is notorious for<br/><br> developing resistance to conventional control strategies (fungicide application and resistance breeding by<br/><br> introgression of R gene). To increase our tool box of disease management strategies available to combat P.<br/><br> infestans, there is a need to explore several new approaches that can lead to more durable solutions to control late<br/><br> blight disease. Using the potato-P. infestans pathosystem, different approaches were used in this thesis with an aim<br/><br> to enhance potato defence and find new resistance sources to P. infestans. In the first approach, exogenous<br/><br> application of a new natural agent, sugar beet extract (SBE), resulted in significant reduction of the size of the<br/><br> infection lesions. The pattern was similar to that seen with application of a known defence-inducing compound, β-<br/><br> aminobutyric acid (BABA). SBE triggered pathogenesis-related protein production with no toxic effect on pathogen<br/><br> growth from SBE was noted, which suggests that the protection conferred by SBE is via induced resistance. BABA<br/><br> is a non-protein amino acid that was shown to induce resistance in different plant species and against various<br/><br> pathogens. However, its mechanism of induced resistance (IR) activation in potato to P.infestans is unclear. Thus, in<br/><br> the second approach, a proteomic and transcriptomic study was conducted in an attempt to unravel the mechanism<br/><br> of BABA-IR in potato. It became clear from our study that BABA results in direct activation of several hormonerelated<br/><br> pathways and defence-related proteins. In the third approach, a constitutively activated defence was<br/><br> discovered in one Phytophthora-resistant potato clone (out of two investigated), which could be an interesting<br/><br> starting material in resistance breeding. In the fourth approach, engineering potato plants by in planta expression of<br/><br> pathogen-associated molecular patterns (Pep13 and flg22) resulted in significant reduction of late blight severity,<br/><br> which could be a suitable strategy to alleviate the severity of plant diseases. An integrated pest management<br/><br> approach, including reduction of the use of the fungicides, is one of the recommendations of the recent EU directive.<br/><br> Thus, it is anticipated that combining induced resistance principle and/or a properly designed transgenic approach<br/><br> with conventional control strategies can reduce fungicide inputs and provide a more efficient and sustainable<br/><br> solution for late blight problem.}}, author = {{Moushib, Laith}}, keywords = {{Oomycetes; plant induced resistance; sustainable agriculture; plant defence activators; plant innate immunity; potato; late blight}}, language = {{eng}}, publisher = {{Department of Biology, Lund University}}, school = {{Lund University}}, title = {{Studies towards late blight control in potato}}, year = {{2013}}, }