Master’s thesis projects
SLU Grogrund projects offer great opportunities for you as a student to carry out your degree projects in partnership with industry. SLU encourages thesis work conducted together with companies, and this is the approach we take within SLU Grogrund, bringing together academia, industry, and society.
A Bachelor's thesis corresponds to ten weeks of full-time study, while a Master's thesis usually covers 20 weeks, sometimes more. The main supervisor and examiner must be based at SLU. External partners may act as co-supervisors or contribute in other ways.
Students registered for thesis projects are covered by insurance.
You can find more information, suggestions, and support regarding thesis work at:
Search among SLU Grogrund´s projects for ideas. You will find the contact details of our project coordinators on these pages.
Examples of previous Bachelor's and Master's theses related to plant breeding
2024
Is faba bean the new Nordic soybean?
Faba beans can be grown in our Nordic climate as an alternative legume crop for food and industrial purposes. But more breeding and research needs to be done to be able to help reach the common goal of improving our personal and environmental health.
Today the world is somewhat unison in the need for increased consumption of beans and other legumes for health and environmental causes. If more legumes are grown in Europe, some of the large amounts of soybean that is imported every year to the EU can be replaced. Soybean is not a crop that can be grown in the northern parts of Europe, due to the climate, but other legumes could take its place, such as peas, common beans and faba beans. Faba beans have a large variation in size and shape, making them perfect for a variety of purposes, both in food and industry. However, it is important to increase the research and breeding of new varieties to produce better crops to help reach the Sustainable Development Goals.
In this study we found that larger seeds of faba beans tend to take longer time to be fully cooked. Another find was that damage of bean weevil do have an effect of shortening the cooking time, but it did not show any effects on the starch content or quality. The low variation of starch quality is an interesting find when it is compared to the results of studies performed in peas. They found that wrinkly seeds had quite a different starch profile (meaning the amounts of the different starch components such as amylose and amylopectin). So far this kind of wrinkly seeds have not been found in faba beans, but who knows what will be found in the future.
The findings of this study are a part of the foundation of the research that can influence future studies in the field, both in breeding and in food sciences.
Read more in the thesis:
The purpose of this study is to get an overview of how plant breeders can screen genotypes of Malus spp for resistance against apple scab or black spot disease. This is done by inoculating the pathogen Venturia inaequalis onto apple tree seedlings and their symptoms are monitored and graded.
The focus is on different application methods that are trialled to get a more physical understanding of the entire process. Factors to consider are which methods of applications are successful, simple, and repeatable. A literary study is done on the current and past methods available, and the methods are compared to get an overview of the pathogen’s requirements to successfully establish an infection on the host in an experimental setting.
Along the literary study, four application methods are tested on young apple trees to get the practical understanding of what a screening entails and what the various methods demand. The result of the experiment will mainly consider the practicality and applicability of each method that is successful.
Read more in the thesis:
Inoculation methods for pathogenesis of Venturia inaequalis : for screening Malus spp for resistance
This thesis aimed to investigate the underlying processes of potential synergistic effects of native soil bacteria exhibiting plant growth-promoting traits and arbuscular mycorrhizal fungi (AMF) in suppressing Fusarium Crown and Root Rot in spring wheat cultivars.
Through greenhouse pot experiments, the efficacy of microbial interventions was evaluated. Despite encountering weaker results in terms of disease suppression than initially expected, this thesis still manages to show significant results with the introduction of AMF and a local microbial community provided by Hasta gård may have in terms of disease suppression. Specifically, observations in spring wheat cultivar Diskett align with existing literature as a promising cultivar in showcasing the positive effects AMF may have, and the synergy it could potentially establish below ground in terms of plant resilience challenged with fungal diseases.
These results, however, should be approached with caution as more tests and replicates for statistical robustness are needed. They could potentially be used as a springboard for further studies in that direction in the pursuit of sustainable practices in the realm of beneficial soil bacteria and fungi acting as biocontrol agents.
Read more in the thesis:
To contribute to sustainable food production, the variable seeding rate in red clover needs to be stabilized. However, what the variation is due to is not fully understood. To set seed, the florets in the clover head need to be cross-pollinated by pollinators. Therefore, it is of interest to investigate possible factors for a low pollination rate and thus a low seed setting rate.
Since floral scent attracts pollinators and can indicate the flower’s susceptibility to pollination, in this study I have investigated how the scent of the clover head changes with pollination, and whether there is any relationship between floral scent and seed set rate.
The study has been based on previously collected material consisting of clover heads and scent samples from them. Analysis of scent samples has focused on specific scent compounds. The scent of open, covered flower heads has been compared with odorants from open heads that had been open pollinated for 48 hours and checked against scent samples from unpollinated bud-stage clover heads. The control was aimed at testing whether certain floral scent compounds increase when the flowers are opened and susceptible to pollination.
In the study, the seeding rate was also investigated, meaning how many percent of the florets per clover head set seed. This is to finally investigate whether there is a relationship between degree of seeding and scent emission.
The result indicates that the content of selected floral scent compounds is generally lowest in the bud stage, then increases when the flowers have bloomed, but then drops when the clover heads have been pollinated and set seed. At the same time, the results indicate that certain flower scent compounds are emitted in more constant levels across the different development stages of the clover head.
Regarding the rate of seeding, the result shows, as expected, a significantly higher seeding in clover heads that were open pollinated, compared to clover heads that were covered. However, no correlation can be seen between the degree of seed setting and the amount of fragrance in pollinated flowers. The work concludes with suggestions on how improvements can produce more reliable results.
Read more in the thesis:
Floral scent emission in red clover in relation to pollination effects
Wheat (Triticum aestivum) is one of the most important crops grown globally together with maize and rice. Many crop species, wheat included, contain undesired traits or traits that could be better adapted to the changing environment. Biotechnological modifications to alter such traits in wheat are much less studied than in many other crops and there are several obstacles to overcome such as lack of efficient standard protocols for the transformation step. One part of the problem is the large size of its genome which makes gene integration more difficult.
One problematic trait is that wheat can take up and store large amounts of cadmium which is a toxic heavy metal that should not be consumed in large quantities. Cadmium is transported into the root cells through different transporters such as NRAMP6. The cadmium accumulates in the grains which are consumed by humans and animals and can cause health problems. Development of biotechnological methods for wheat transformation is therefore desired. With such methods, the undesired cadmium uptake and storage in wheat could potentially be decreased.
The aim of this MSc project was to develop an improved transformation method to facilitate gene editing in wheat, and the target was the NRAMP6 transporter. Additionally, a new plasmid for this purpose was designed and successfully cloned in silico using SnapGene. Two new transformation methods were tested in this project: floral dipping in an Agrobacterium solution and Agrobacterium pipetting. They both utilize Agrobacterium tumefaciens’ natural ability to transfer part of its DNA into the genome of a plant cell. A plasmid with a transfer-DNA (T-DNA) containing a CRISPR/Cas9 construct targeting the NRAMP6 transporter was transformed into A. tumefaciens. The Agrobacterium was thereafter added to an infiltration solution which was used to treat pre-anthesis wheat spikes with either floral dipping or Agrobacterium pipetting with the purpose of transferring the T-DNA into them.
Both methods managed to produce surviving spikes and the results showed that spikes treated with the dipping method had a higher survival rate. The surviving spikes were furthermore able to produce seeds, but the seed set was low for both the treated spikes and the controls. A hygromycin selection was then used on the mature seeds to test for T-DNA insertion.
In total, 135 treated seeds were harvested but only 46 of them were placed on the hygromycin selection medium. None of the 46 seeds germinated on the hygromycin in the set timeframe of the project and the number of potentially successful transformants could therefore not be determined.
Despite inconclusive results, this MSc project have contributed to increased knowledge of genetic modifications in wheat and have laid a foundation for continued progress within the important area of gene transformation of agricultural crops.
Read more in the thesis:
Effective disease management is dependent on accurate disease diagnosis. It might be challenging to diagnose the right cause based just on the visible symptoms because various abiotic factors including water stress, drought, and nutrient deficiency can all create similar symptoms. The primary sign of the disease virus yellows, which is caused by several viruses, is the yellowing of sugar beet leaves. Gradually, the disease may spread within the entire field and cause a massive yield loss.
According to current research, three main viruses are responsible for viral yellows in sugar beet in Sweden: beet yellows virus, beet mild yellowing virus and beet chlorosis virus. All these viruses are transmitted by aphids. Earlier, neonicotinoid insecticide was used to successfully suppress virus yellows. However, because of the neonicotinoids' severe environmental effects, they have been prohibited in Europe since 2018. Consequently, there is an increased risk for virus yellows disease in Sweden's sugar beet crop.
The current study was able to identify beet mild yellowing virus and beet chlorosis virus in sugar beet field samples that had been collected from five locations in Skåne, 2023. Symptomatic sugar beet leaves collected from two locations were infected with beet mild yellowing virus and leaves from the other three locations were infected with beet chlorosis virus. Analyses showed that the virus isolates identified in the present study are different from those previously found in Sweden, which means that the viruses are more variable than we knew. These new virus variants could have been brought into Sweden by migrating aphids.
Because of limited knowledge of the virus, there is a lot of room for new investigations. Breeders developing new sugar beet cultivars to be grown in Sweden can utilize this information to determine the spectrum of resistance that the plants require. It is critical to have thorough knowledge about these viruses to manage infection and stop their spread, hence reducing yield loss due to viral yellows.
Recently it was found that there are some other smaller virus-like molecules living together with those viruses mentioned above called “associated RNA molecules”. Infection of both viruses and associated molecules together can lead to severe yield loss and control strategies would be more challenging than those in single virus infection. However, in this study, associated RNA molecules could not be found in the virus-infected samples.
Read more in the thesis:
Survey of aphid-transmitted viruses and associated RNA molecules in Swedish sugar beet crops
The Green Revolution, a pivotal era in agriculture, significantly enhanced crop yields through various means such as plant breeding, increased use of fertilizers and pesticides, and mechanization. However, despite its contributions to food security and economic development, modern agricultural practices face relevant challenges posed by climate changes and globalized markets that have exacerbated the incidence of crop diseases.
Synthetic chemical pesticides, while effective, raise increasing concerns about long-term sustainability and environmental impacts. Integrated Disease Management (IDM) and biological control offer promising alternatives by employing eco-friendly approaches to combat crop diseases. Nevertheless, little is understood about how genetic variation in plants influences how effective biological control agents (BCAs) are.
This study aims to investigate the genetic diversity among winter wheat genotypes concerning fusarium foot rot (FFR) susceptibility and their response to the fungal biocontrol agent Clonostachys rosea during FFR infection. Hypothesizing differences in resistance to FFR and compatibility with C. rosea among winter wheat genotypes in a bioassay, where disease severity, and traits associated with root length, shoot length, and plant length under two treatments: F. graminearum (Fg) and Fg with C. rosea (FgCr) were measured.
Through statistical analyses and correlation studies, significant differences show C. rosea effectiveness in reducing disease severity and improving plant growth, highlighting its potential for sustainable disease management. Furthermore, correlations between disease severity, plant growth, and biocontrol efficacy were observed, providing insights into plant-pathogen interactions. Additionally, using a 20K marker array, a genome-wide association study was also performed. Genome-wide association studies identified significant genetic markers associated with disease score, shoot length, and root length, showing different locations in the genome. Additionally, the bioassay was performed using Trichoderma harzianum as a BCA, where the effect of treatment was not significant for any of the traits.
Read more in the thesis:
Genetic variation in wheat for fusarium foot rot and its biocontrol by Clonostachys rosea
2023
Reap the Benefit of Rapeseed
Rapesed cake, the protein-rich by-product of rapeseed oil extraction, grasps great potential as a source of nutrition for both humans and livestock. However, its high levels of glucosinolates (GSLs) have long been a problem due to their anti-nutritional properties and extreme bitterness when hydrolyzed. These unfavorable characteristics have limited the use of rapeseed cake in both human and animal diets.
Among the different types of GSLs, aliphatic GSLs have been identified as the major culprits behind these negative properties. To address this issue, a precision plant breeding study was conducted to reduce the levels of long and short-chain aliphatic GSLs in rapeseed cake. This research work employed a cutting-edge genetic tool known as CRISPR to target the principal regulator of aliphatic GSL biosynthesis, MYB28. This transcription factor positively regulates several genes in different stages of GSL biosynthesis, such as side chain elongation and core structure formation. So, the absence of this transcription factor will automatically restrict the aliphatic GSL biosynthesis. They identified six out of seven MYB28 paralogs in the cv. Kumily genome and designed two sgRNAs to target specific regions within both MYB-type HTH domains of MYB28 protein.
The RNP complex that consists of sgRNA and Cas9 protein was introduced into cv. Kumily protoplasts to induce mutation. Subsequently, the transformed protoplasts were cultured under in-vitro conditions to promote organogenesis. Genomic DNA was extracted from the true leaves of three regenerated plants and seven randomly selected callus samples and screened for mutation.
In conclusion, this study has identified a successful sgRNA that can initiate CRISPR/Cas9-mediated mutagenesis at MYB28, as confirmed by the mutation event in LOC106428039. The research is still ongoing, with the continuation of screening the regenerated shoots from the transfected protoplasts to identify desirable homozygous mutation lines. This exciting work paves the way for a future where rapeseed cake can be used more effectively for human nutrition and improved livestock feed.
Read more in the thesis:
Seed yield in red clover (Trifolium pratense L.) is in today’s modern commercially grown cultivars highly variable and inconsistent, which affect the seed production nationally in Sweden negatively. Previous research that have investigated the interacting factors have found that ecological relationships are complex and often difficult to interpret.
The study looked at data from red clover fields at 26 locations in Skåne county (the southernmost province of Sweden) over three years 2018 – 2020. It investigated relationships and co-variance in interactions between seed set factors pollinator density, bumble bee density, pollinator & bumble bee densities in relation to number of open flowers and percentage of flowers that set seed in conjunction with seed yield achieved.
The results show that number of flowers strongly correlate with number of pollinators in the fields, but at the same time that higher numbers of flowers and pollinators negatively correlates with grade of seed set. The number of pollinators relative to number of flowers also show a negative correlation which suggests that a higher number of pollinators in conjunction with a lower number of flowers directly corresponds to less effective pollination.
The study also looked into how these correlations vary with time during the growing season, which showed that the correlations that were negative when looking over the season in a whole in reality were positive during the first part of the season and then turned negative by the latter half of the season; this applies to correlation between pollinator & relative pollinator density and seed set. This suggests that the proven factors regarding seed yield in clover do vary and co-vary over time, which should be investigated further in future studies.
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There is significant evidence to suggest that diets that include high levels of meat consumption have negative effects on both the environment and human health. As a result, efforts are being made to identify and characterize more plant-based proteins, such as those found in rapeseed. Rapeseed is the second-largest oilseed crop worldwide and is primarily used to produce edible oils through mechanical separation methods. During this process, a protein-rich by-product called press cake is produced, which is currently utilized as a source of protein in animal feed.
Rapeseed press cake primarily consists of fibre (30%), protein (27-30%) and residual oil (20%). The use of rapeseed protein in food is limited because of its bitter taste and the antinutritional components it contains. In order to effectively recover protein from rapeseed press cake, it is necessary to scale up the process beyond laboratory-scale setups. Researchers from the Department of Food Technology, Engineering and Nutrition at Lund University have successfully achieved this; consequently, the current study aimed to further enhance the process's capacity and protein recovery yield in a pilot-scale setup.
The study aimed to recover proteins from rapeseed press cake using the salt extraction method at a concentration of 0.25M and a pH of 7, followed by isoelectric precipitation at pH 3.5 and a decanter centrifuge. The optimal processing parameters for the decanter centrifuge during the first protein recovery step were an inlet feed rate of 60 L/h, 2000xg acceleration, 50 rpm differential speed, and a weir disc with an inner diameter of 68 mm. A pH of 7 was suitable for a gentler extraction of proteins, with the addition of sodium chloride resulting in an extraction coefficient of 61%. Based on thorough analysis, it was determined that the most suitable set of processing parameters for the second phase of protein recovery were an inlet flow rate of 10 L/h, 4000xg acceleration, 6 rpm differential speed, and a 56 weir disc inner diameter. The latter enhanced the overall process capability without any adverse effects on critical factors such as dry matter and protein content of the precipitate.
The study found that scraping equipment surfaces resulted in a significant increase in protein recovery yield. The yield increased from 17% to 29% under the selected processing conditions.
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Every year the crops of the world are supplied with a hundred million tons of nitrogen in the form of inorganic fertilizer which is mainly produced using fossil fuels. Regrettably, half of it is leached out of the fields and is causing pollution, eutrophication, and increased greenhouse gas emissions.
Thankfully, there is another way to provide the crops with essential nitrogen. Certain soil bacteria in symbiosis with legumes can transform (“fix”) the nitrogen in the air into organic forms that plants can utilize. One group of legumes excellent for this purpose is the clovers, who enter a symbiotic relationship with the species Rhizobium leguminosarum variant trifolii. The symbiosis requires complex molecular communication and several hundred symbiosis genes to function. Here we attempt to sample the Swedish diversity of red clover-associated Rhizobium and determine their level of genetic variation. For this we collected 16 Rhizobium isolates from clover roots and performed gene sequencing of one species-determining gene and four symbiosis genes.
The analysed Swedish Rhizobium isolates were highly genetically similar; the species-determining gene sequences were near identical, showing that all isolates were closely related. However, the symbiosis-specific genes showed some variability, and that variability could be roughly traced to the sampling location, to north and south of Sweden. By comparing these Rhizobium sequences to published sequences worldwide we could determine that the Swedish isolates are indeed very closely related and, considering the similarities, can possibly share a single geographical origin. To understand the variability and its effects in the symbiosis-specific genes, we need to extend our work to include further genetical and functional analysis of our Rhizobium.
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Oat, broad beans and soybeans are all common and important food crops. They play an important role worldwide in terms of both nutrition and economy. As for most plants, different diseases can emerge in these crops, causing considerable yield losses. One great concern is virus infections in plants. Barley yellow dwarf virus (BYDV), bean leafroll virus (BLRV), and other related viruses of the genera luteoviruses and poleroviruses are commonly infecting the aforementioned crops. Symptoms of infection include discolouration and dwarfism, and transmission is mainly vectored by aphids.
The viruses studied in this project have their genetic material in the form of RNA. Reverse transcription polymerase chain reaction (RT-PCR) was performed for a nucleic acid-based detection of luteovirus and polerovirus in symptomatic and non-symptomatic leaves from the plants mentioned above, and in aphids. The aphids were collected in 2014 and 2020. The great amount of aphids in these years caused extensive spread of virus in cereals and damage following years.
No sequence of viral origin was detected in any of the samples. This was also the case for the positive control sample, containing aphids known to carry BYDV. For the positive control, a high background amplification in the PCR might be the explanation for absence of identified viral RNA sequences. For the plant samples, the negative results are believed to be an indication that they were not infected with luteovirus or polerovirus. Results from analyses of older aphid samples did not indicate any presence of virus, although due to uncertain results, no definitive conclusions can be drawn.
More research on aphids could lead to an increased knowledge of the correlation between the vectored transmission and virus epidemics in crops. This knowledge could in turn be useful when creating guidelines of more accurate insecticide use, resulting in secured yields, reduced economical losses and less negative environmental impact.
Read more in the thesis:
Molecular detection of luteovirus and polerovirus : in oat, broad bean, soybean and aphids
The cultivation of oilseed rape faces challenges caused by pests and pathogens, and soil-borne pathogens such as Plasmodiaphora brassicae (clubroot) are among the main causes of disease. Verticillium longisporum is anothersoil-borne pathogen, which causes the verticillium stem striping disease in Brassica plants, including oilseed rape.
In this project the fungal biological control agent Clonostachys rosea was used in an attempt to utilize biological control of verticillium stem striping disease in oilseed rape. The main in planta experiment was perfomed to investigate this hypothesis, but the results showed no significant effect of C. rosea to prevent verticillium stem striping disease in oilseed rape.
Three in vitro experiments were also performed to study the interactions between these two fungi, C. rosea and V. longisporum, and showed that C. rosea can inhibit the growth of V. longisporum in the in vitro setting.
In summary, C. rosea show some potential of being able to control V. longisporum in an in vitro setting, but none in planta.
Read more in the thesis:
Biological control of verticillium stem striping disease on oilseed rape : fungi as friends and foes