Final report for GNE20-243
Project Information
Emerging fungal plant diseases such as Fusarium wilt of tomato cause significant losses for growers in the northeast United States. Although some members of the Fusarium oxysporum Species Complex (FOSC) are responsible for this plant disease on over 100 crops, most isolates live in the soil or inhabit plants without causing disease. In fact, because of the complex evolutionary history of this group and the multiple modes of genetic exchange available, the isolates that cause Fusarium wilt can be very closely related to isolates that do not. As these isolates occupy the same ecological niche in agroecosystems, it is important to understand how these isolates relate to and impact one another. Improving this understanding helps researchers understand risks related to pathogen emergence and aid in developing better diagnostic tools. Therefore, it is crucial that we understand the evolutionary and ecological context from which pathogenicity emerges. This necessitates characterizing host adaptation among nonpathogenic isolates. Therefore, we propose to conduct a systematic sampling of FOSC isolated from specific parts of asymptomatic tomato plants and agricultural and non-agricultural soil. This sampling will allow meaningful comparisons to evaluate the genetic diversity of nonpathogenic FOSC in Pennsylvania tomato production, and identify factors that may be influencing population structure, and adaptation to tomato. Specifically, we will assess 1. Agricultural production, 2. Crop History, 3. Time, and 4. Host Variety. We will also assess current diagnostic approaches for Fusarium-associated diseases. We will identify educational needs of diagnosticians for Fusarium identification and provide resources to address those needs.
We seek to characterize nonpathogenic F. oxysporum occupying the same ecological niche as pathogenic isolates to better understand host adaptation and genetic exchange within the species complex.
Objective 1: Determine if F. oxysporum soil population is impacted by agricultural production (Compare populations from agricultural soil vs. nonagricultural soil).
Objective 2: Determine if F. oxysporum populations associated with tomato production are shaped by geographic location. (Compare populations from Pennsylvania vs. Florida).
Objective 3: Determine if F. oxysporum populations associated with tomato production change over the course of the growing season (Compare populations from Timepoint 1: time of transplanting seedlings vs. Timepoint 2: harvesting)
Objective 4: Determine if Fusarium wilt resistance genes impact the F. oxysporum populations asymptomatically colonizing tomato (Compare populations from different tomato lines with differing Fol resistance genes).
Objective 5: Identify current practices in Fusarium identification in plant diagnostic clinics and identify educational needs among diagnosticians.
The purpose of this project is to characterize nonpathogenic F. oxysporum occupying the same ecological niche as pathogenic isolates so as to better understand emergence of pathogenicity in this system and lay the groundwork for better diagnostic strategies. This research is important as some strains of F. oxysporum cause damaging diseases on important vegetable crops in Pennsylvania. Plant pathogenic F. oxysporum are specific to certain hosts are grouped as formae speciales (f.sp). Tomato is one of the most profitable vegetable crops grown in Pennsylvania and is impacted by Fo f. sp. lycopersici (Fol). In 2015, open-air, fresh market tomato production was valued at $33.2 million1.
Soil health and effectively managing soilborne plant pathogens is especially important in the northeast US, as many vegetable growers are transitioning to high tunnel production. Although this production technique may extend the growing season and lead to increase yields, the intensification of soil use may also lead to issues with soilborne plant pathogens such as F. oxysporum2. Growers face challenges if they find Fusarium wilt in their fields. F. oxysporum can survive in the soil for several years by colonizing degraded plant material, the roots of other crops, or by forming survival spores4–6.
Options for soil treatments exist such as steaming, solarization, and anaerobic disinfestation treatments7. These treatments involve infrastructural barriers, as they require specialized equipment, additional labor, and training. Even if growers can afford to use other effective soil treatments such as using disease-free seed and resistant tomato varieties, there is the looming possibility that certain races of Fol, will spread to new regions, or new races that overcome current genetic resistance can emerge 8. Fol can also be problematic in an agricultural setting due to the multiple ecological niches occupied by plant pathogenic F. oxysporum and their ambiguous relationship with nonpathogenic strains of F. oxysporum 4,9,10. Therefore, we need to better understand the factors contributing to emergence of this pathogen from closely related nonpathogenic relatives9. As nonpathogenic strains of FOSC are highly diverse in terms of ecological function and evolutionary background, we seek to clarify the blurry spectrum between nonpathogen and pathogen and examine how these individuals may interact.
These topics merit investigation because of the downstream impacts of understanding emergence of pathogenicity of Fusarium wilt, and on diagnostic capability. When researchers can better assess risk of pathogen emergence, we are better prepared to address the problem when it happens or implement strategies to reduce the risk. Ultimately, emerging pathogens such as those that cause Fusarium wilt, place an economic burden on vegetable growers in the northeast US as they lose part of their crops to the disease and spend time and money on management.
Additionally, providing diagnostic tools and education in Fusarium identification also contributes to reducing economic losses for growers. Diagnosticians are responsible for providing fast and accurate identification of pathogens and management recommendations for growers to respond to the specific pathogen. When diagnosticians help growers they are less likely to use unnecessary chemical treatments that add additional environmental impact.
Research
To assess the genetic dynamics of FOSC in tomato agroecosystems in Pennsylvania, we conducted a systematic sampling of FOSC isolated from specific parts of asymptomatic tomato plants, rhizosphere soil, and soil from neighboring non-agricultural soil. Samples were collected at the Russel E. Larson Agricultural Research Center in Pennsylvania Furnace, PA and at the University of Florida Gulf Coast Research and Education Center in Wimauma, FL.
Sampling locations: Two fields were sampled at the Penn State University Russell E. Larson Research Center in Pennsylvania Furnace, PA. These fields have a history of varied agricultural production. Tomatoes have not been grown in these plots since 2011. Since then, squash, onions, celery, and soybean were grown in these fields. Soil was sampled from eight plots at the beginning of the tomato growing season and again from the same plots at the end of the growing season. Four different varieties of tomatoes were grown in these fields. Each variety has resistance to different races of F. oxysporum f. sp. lycopersici (Fol), the fungus that causes a vascular wilt disease in tomato. Each tomato variety was grown in four plots, totaling 16 plots per variety. Four plants were sampled from each plot. The trial was repeated in 2021, with the inclusion of 5 additional tomato lines with varying Fol resistance genes.
Adjacent to the production area of the research farm are wooded areas leading up to mountainous terrain of the Rothrock State forest. Soil samples were taken at the edge of the forest and an area on the beginning of the incline.
In 2021, 4 of the tomato lines included in the 2021 PA field trial were included in a similar field trial at the University of Florida Gulf Coast Research Center in Wimauma, FL. These fields have been used for tomato production for several years.
Isolating F. oxysporum from field samples
Whole plants and their roots were sampled at the mature fruit stage (8-12 weeks after transplanting). Plants were dug up so much of the root system would remain in-tact. Plants were labeled and rinsed before being processed in the lab. Then, the plant tissue was cut into 10 ~1cm pieces in equal intervals up the length of the stem. Additionally, two pieces of the crown, and 10 pieces across the roots. Tissue was surface sterilized for 2 minutes in a 2% commercial bleach solution, and then rinsed with water. Tissue was air dried, and plated on Nash-Snyder media, which is selective for Fusarium spp.
Soil samples were collected by taking seven soil cores in between each plant in a given plot and pooled into one sample. Soil samples were allowed to air dry in the lab, then passed through a sieve to remove rocks and debris. 1 gram of soil was diluted in 50 mL of water and a serial dilution series of soil suspensions were made and plated on Komada’s media and Nash-Snyder media, as both are selective for Fusarium spp.
Plates were kept in a dark incubator set to at 25 C and were monitored daily for fungal growth. Fungal growth emerging from the plated plant tissue and soil dilution plates were sub-cultured on 1⁄4 strength potato dextrose agar. To obtain pure isolates, subcultures were “cleaned” via hyphal tip transfers or single spore isolations when necessary. Isolates displaying morphology consistent with F. oxysporum were prepared for long-term storage as well as DNA extraction.
DNA extractions, PCR, and sequencing
Fungal tissue was harvested from ¼ PDA plates using an autoclaved toothpick. The tissue was crushed under liquid nitrogen using a micropestle, then CTAB was added to lyse fungal cells. Ammonium acetate, isopropanol and ethanol were used to precipitate and clean nucleic acid in the samples. DNA was quantified and the quality was assessed using a spectrophotometer.
Extracted DNA that meet necessary quality standards were subject to Polymerase Chain Reaction (PCR) to amplify the translation elongation factor 1- (TEF) region. TEF is a common barcoding region for Fusarium24, and can be a reliable way to identify the species of a Fusarium culture. The success of each PCR was assessed using gel electrophoresis and visualizing the presence or absence of a band at approximately 600 bp. Samples that showed a successful PCR product were selected for sequencing.
PCR products were cleaned with ExoSAP-IT kits to remove unincorporated primers and dNTPs. The samples were then submitted to the Penn State University Genomics Core Facility to undergo Sanger Sequencing on an Applied Biosystems 3730XL DNA Analyzer.
Data Analysis
Sequences of fungal isolate TEF sequences were returned to us from the PSU Genomics Core facility as .ab1 files. The chromatograms of the sequences were visually assessed using the software, Geneious Prime. Sequences were trimmed and edited manually, and poor quality sequences were discarded. Sequences with good quality chromatograms were subject to a BLAST search using the curated TEF database, FUSARIUM ID v.3.0. This allowed us to identify the species of each isolate. Sequences from the isolates shown to be F. oxysporum were selected for genetic diversity analyses.
Sequences were coded with metadata about the fungal isolate such as substrate (root, crown, stem, soil), location, and year. Sequences were aligned with standard settings in MUSCLE, and imported into GenAlEx for haplotype assignment and data formatting. The R package ‘poppr’ was used to calculate statistics used to measure genetic diversity.
Previous studies investigating F. oxysporum diversity in both agricultural and non- agricultural systems have observed high diversity among isolates. To capture this diversity, we aimed to isolate up to 40 isolates from each soil sample, and up to 15 isolates per plant. This sampling follows the approach used by Demers et al. (2015), as we would like to draw comparisons to their results. However, we found a low success rate of recovering F. oxysporum from the samples. For example, we isolated 1,414 fungal subcultures from plant material from 2020 that had morphology consistent with F. oxysporum. As these isolates moved through our workflow and isolates were discarded at each step, we only ended up with 201 F. oxysporum isolates with good quality TEF sequences that could be used in our downstream analyses (Table 1).
Table 1:
|
Tomato Line |
Tissue Type |
Plot/Rep |
Number of fungal subcultures |
Number of F. oxysporum isolates with good quality TEF sequence |
|
Bonny Best |
crown |
1 |
16 |
2 |
|
2 |
16 |
4 |
||
|
3 |
11 |
3 |
||
|
4 |
21 |
8 |
||
|
roots |
1 |
35 |
13 |
|
|
2 |
27 |
7 |
||
|
3 |
21 |
4 |
||
|
4 |
41 |
8 |
||
|
stems |
1 |
49 |
1 |
|
|
2 |
59 |
3 |
||
|
3 |
50 |
3 |
||
|
4 |
44 |
1 |
||
|
Bradley |
crown |
1 |
15 |
4 |
|
2 |
12 |
1 |
||
|
3 |
21 |
18 |
||
|
4 |
16 |
8 |
||
|
roots |
1 |
24 |
3 |
|
|
2 |
35 |
10 |
||
|
3 |
33 |
7 |
||
|
4 |
30 |
12 |
||
|
stems |
1 |
52 |
4 |
|
|
2 |
40 |
1 |
||
|
3 |
56 |
3 |
||
|
4 |
46 |
0 |
||
|
Floradade |
crown |
1 |
10 |
3 |
|
2 |
8 |
3 |
||
|
3 |
8 |
2 |
||
|
4 |
18 |
5 |
||
|
roots |
1 |
25 |
6 |
|
|
2 |
17 |
3 |
||
|
3 |
7 |
1 |
||
|
4 |
32 |
2 |
||
|
stems |
1 |
26 |
0 |
|
|
2 |
45 |
3 |
||
|
3 |
39 |
3 |
||
|
4 |
49 |
0 |
||
|
Mountain Merit |
crown |
1 |
19 |
7 |
|
2 |
2 |
0 |
||
|
3 |
9 |
5 |
||
|
4 |
15 |
4 |
||
|
roots |
1 |
36 |
4 |
|
|
2 |
12 |
0 |
||
|
3 |
29 |
7 |
||
|
4 |
38 |
6 |
||
|
stems |
1 |
62 |
3 |
|
|
2 |
33 |
3 |
||
|
3 |
54 |
3 |
||
|
4 |
51 |
0 |
We moved sets of isolates through the workflow in batches and were able to adapt our screening process as we processed samples. For example, we noticed we were frequently selecting F. incarnatum-equiseti species complex and F. solani species complex isolates for sequencing, as their morphology can be similar to that of F. oxysporum. We were then able to filter out those samples earlier in the workflow. We processed soil samples later in our project and had a higher success of removing cultures that were not F. oxysporum (Table 2, Table 3.)
Table 2: Species composition of in planta isolates sequenced at TEF (2020, 2021)
|
Fusarium species complex |
Species name |
Number of isolates |
|
F. tricinctum species complex |
acuminatum |
3 |
|
F. chlamydosporum species complex |
armeniacum |
3 |
|
F. incarnatum-equiseti species complex |
clavum |
18 |
|
F. incarnatum-equiseti species complex |
compactum |
33 |
|
F. solani species complex |
falciforme |
2 |
|
F. incarnatum-equiseti species complex |
undescribed |
2 |
|
F. tricinctum species complex |
undescribed |
1 |
|
F. fujikuroi species complex |
fujikuroi |
3 |
|
F. incarnatum-equiseti species complex |
ipomoeae |
6 |
|
F. incarnatum-equiseti species complex |
luffae |
2 |
|
F. solani species complex |
parceramosum |
1 |
|
F. solani species complex |
solani |
19 |
|
F. sambucinum species complex |
sporotrichioides |
2 |
|
F. oxysporum species complex |
oxysporum |
253 |
Table 3: Species composition of soil isolates sequenced at TEF (2020, 2021, 2023)
|
Fusarium species complex |
Species Name |
Number of isolates |
|
F. incarnatum-equiseti species complex |
clavum |
1 |
|
F. solani species complex |
solani |
23 |
|
F. sambucinum species complex |
sporotrichioides |
1 |
|
F. solani species complex |
waltergamsii |
1 |
|
F. oxysporum species complex |
oxysporum |
235 |
Overall, we were able to generate good quality TEF sequences of 485 isolates of F. oxysporum isolated from asymptomatic tomato plants, soil from fields associated with tomato production, and adjacent non-agricultural lands (Table 4).
Table 4: F. oxysporum isolates sequenced at TEF
|
Population |
Substrate |
Location |
Year |
# isolates |
|
1 |
soil |
PA tomato field |
2023 |
65 |
|
2 |
soil |
PA tomato field |
2020 |
40 |
|
3 |
soil |
PA tomato field |
2021 |
10 |
|
4 |
soil |
FL tomato field |
2021 |
112 |
|
5 |
soil |
PA non-agricultural land |
2020 |
1 |
|
6 |
soil |
PA non-agricultural land |
2023 |
4 |
|
7 |
roots |
PA tomato field |
2020 |
93 |
|
8 |
roots |
PA tomato field |
2021 |
33 |
|
9 |
crown |
PA tomato field |
2020 |
77 |
|
10 |
crown |
PA tomato field |
2021 |
13 |
|
11 |
stem |
PA tomato field |
2020 |
31 |
|
12 |
stem |
PA tomato field |
2021 |
6 |
Objective 1 (Determine if F. oxysporum soil population is impacted by agricultural production), Objective 2 (Determine if F. oxysporum associated with tomato is shaped by the geographic location of the field).
To address Objectives 1 and 2, we stratified our dataset of F. oxysporum TEF sequence types by substrate and location. This allowed us to calculate measures of genetic diversity from populations of F. oxysporum isolated from agricultural production and non-agricultural production (Table 5). It should be noted that we had an extremely low recovery rate of F. oxysporum from non-agricultural soil samples. Across all soil samples collected from non-agricultural land, 126 soil dilution plates were generated, resulting in a total of 652 colony forming units. Only 5 of those colonies resulted in a sequenced F. oxysporum isolates. As the population size of F. oxysporum isolated from neighboring non-agricultural land is much lower than the population sizes of F. oxysporum isolated from the soil of tomato fields, the statistics displayed in Table 5 should be considered accordingly. However, the numbers indicate that there is higher diversity of F. oxysporum in the soil of PA tomato fields than in the soil of neighboring wooded area not subjected to agricultural production. All MLGs observed in the non-agricultural land were also observed in the nearby agricultural soil. These findings could be attributed to a higher diversity of other fungi in the non-agricultural soil that would out-compete F. oxysporum isolates that may be present. This would suggest that F. oxysporum could be adapted to agricultural production, as they are over-represented in these samples.
Our results also show that the population of F. oxysporum isolated from PA tomato fields has a much higher diversity than that of the population isolated from FL tomato fields. These findings could be attributed to the history of the sampled fields. If certain F. oxysporum genotypes are associated with tomato production, many years of tomato production could select for such isolates compared to fields with varied agricultural practices.
Table 5: Diversity measures of F. oxysporum populations isolated from soil across three locations
|
Population |
N |
MLG |
eMLG |
SE |
H |
E.5 |
Hexp |
|
PA tomato field soil |
115 |
13 |
5.16 |
1.15 |
1.93 |
0.65 |
0.10 |
|
PA non-ag soil |
5 |
4 |
4 |
0 |
1.33 |
0.92 |
0.08 |
|
FL tomato field soil |
112 |
5 |
1.44 |
0.61 |
0.24 |
0.35 |
0.01 |
Key for Diversity Measures
N = number of individuals observed
MLG = number of multilocus genotypes observed. Genotypic richness
eMLG = number of expected MLG at the smallest sample size >10 based on rarefaction
SE = standard error based on MLG
H = Shannon-Wiener Index of MLG diversity (Shannon, 2001)
E.5 = genotypic evenness (Pielou, 1975; Ludwig & Reynolds, 1988, Grunwald et al. 2003).
Hexp = Nei’s unbiased gene diversity (Nei, 1978).
Objective 3 (Determine if F. oxysporum soil population changes over the course of the growing season)
Due to the low recovery rate of F. oxysporum from the field samples, we did not have a high enough sample size for sets of F. oxysporum isolated at the beginning and end of each growing season. However, we can draw comparisons between the diversity of F. oxysporum soil populations of the same PA tomato fields across several years. Based on measures of genotypic diversity, all three populations had similar levels of F. oxysporum diversity (Table 6). This suggests that the diversity of F. oxysporum in agricultural soil remains stable over the years and that location, or field history has a greater impact on F. oxysporum diversity.
Table 6: Diversity measures of F. oxysporum populations isolated from soil across three years
|
Population |
N |
MLG |
eMLG |
SE |
H |
E.5 |
Hexp |
|
PA tomato field soil 2020 |
40 |
10 |
5.3 |
1.1 |
1.85 |
0.67 |
0.09 |
|
PA tomato field soil 2021 |
10 |
6 |
6 |
0 |
1.64 |
0.85 |
0.1 |
|
PA tomato field soil 2023 |
65 |
5 |
5 |
1.06 |
1.8 |
0.71 |
0.11 |
To address Objective 4 (Determine if Fusarium wilt resistance genes impact the F. oxysporum populations asymptomatically colonizing tomato).
Due to the low recovery rate of F. oxysporum from the field samples, we did not have a high enough sample size for sets of F. oxysporum isolated from tomato lines with differing resistance to Fusarium wilt. However, we were able to address this objective by assessing other tools that are used to characterize F. oxysporum colonizing tomato. Seven qPCR markers from previously published studies were assessed as candidates for quantifying F. oxysporum in planta. It is methodologically challenging to measure fungal biomass of endophytes, as they tend to have a much lower biomass than pathogenic isolates. With F. oxysporum, there is the additional challenge of differentiating nonpathogenic isolates from pathogenic isolates, as they can have high genetic similarity at their core genomes. In order to characterize representatives of our collection of F. oxysporum associated with tomato, current markers need to be assessed with strict metrics. Testing a panel of qPCR markers against representatives of our F. oxysporum collection allowed us to identify the most appropriate assay to use in characterizing F. oxysporum asymptomatically colonizing tomato. This approach can be used to test the impact of Fol resistance genes on asymptomatic F. oxysporum colonization of tomato.
Objective 5 (Identify current practices in Fusarium identification in plant diagnostic clinics and identify educational needs among diagnosticians). See Outreach Section for more details.
Our research provides a broader context regarding Fusarium oxysporum associated with vegetable production. F. oxysporum is the causal agent of the economically important Fusarium wilt disease. However, it is also a species that is found in many ecological niches, including soil and asymptomatic plants. As nonpathogenic isolates are closely related to pathogenic isolates and occupy the same ecological niche, understanding nonpathogenic isolates is crucial for understanding Fusarium wilt. Our research provides evidence of factors that impact F. oxysporum diversity, such as location and field history. Furthermore, as other studies use TEF to assess F. oxysporum diversity, we can compare our results to other published studies from around the world, giving our results a global context. Finally, we were able to identify tools to better characterize asymptomatic F. oxysporum in planta.
Education & Outreach Activities and Participation Summary
Participation Summary:
Our major outreach goals aim to strengthen infrastructure that provide valuable support to growers dealing with Fusarium diseases in the northeast US. The National Plant Diagnostic Network (NPDN) is a consortium of plant diagnostic clinics across academia, state and federal governments, and industry. Its purpose is to facilitate information and resource sharing so reports of new diseases can be communicated to those charged with responding to such outbreaks. Plant disease clinics provide the most important first step in determining the most appropriate management response to a certain disease. Having an accurate and fast diagnosis ensures that growers are responding to a disease using the right tools at the right time. This prevents growers from spending money on unnecessary treatments or putting avoidable chemical input in the environment. Acting fast and appropriately can minimize losses and maximize profits for growers. As Fusarium diseases can be challenging to diagnose, there is a need for continued education on best practices for diagnosticians. Determining current practices and educational needs is the first necessary step in adapting and developing workshops, trainings, and other resources. Therefore, we propose to conduct a survey for members of the NPDN to determine current practices and educational needs in Fusarium diagnostics. This information is important to Fusarium experts, such as Dr. David Geiser, who regularly offer practical workshops on Fusarium.
Another resource used by diagnosticians are “Disease Notes”, short, peer-reviewed articles published in Plant Diseaset hat report first occurrences of plant pathogens on a new host or in a new geographic region. These reports are crucial for documenting and cataloging distribution and impact of plant pathogens. Diagnosticians use information from these reports when making diagnoses and assessing risk and appropriate management recommendation. Diagnosticians are also frequent authors of these reports. Diseases associated with Fusarium are notoriously difficult to describe, particularly when it comes to establishing an isolate as the causal agent of the observed disease16. Differentiating secondary colonizers from true pathogens can be challenging, and oftentimes, multiple species may be involved in the disease. Furthermore, there are specific morphological characteristics and molecular protocols that will provide the best information for an identification, but with changing identification tools, taxonomy, and nomenclature rules, all of this information may not be clear to diagnosticians16,24. Therefore, we believe a short article providing guidelines for writing Disease Notes on Fusarium-associated diseases will be very helpful to the community. All participants worked on this article together, each providing expertise from a different perspective. This article was published in the NPDN Communicator. This newsletter often features informative articles such as this to the plant pathology community.
Additionally, the findings of this research project were communicated to different audiences, with the emphasis of the results contextualized for each audience. The results were presented as a poster presentation to an academic audience at the APS annual conference, Plant Health 2023.
I also presented my research objectives, methodologies, and future steps for Objectives 1-5 during a lab meeting with four fungal biology labs. As several new graduate students were present, it was a helpful learning experience for them to learn about methodologies in fungal isolation and survey design. Additionally, I presented the experimental design and preliminary progress on Objectives 1-5 in a seminar I gave to my department. I placed this project in the context of the other FOSC projects I am working on.
To address Objective 5, we have had several consultations with professionals experienced in social sciences as well as the director of the NPDN, Dr. Neil McRoberts. Additionally, we met with the NPDN’s Professional Development Committee to receive feedback on our survey and to have a broad discussion of the committee’s goals for providing continuing education and training for diagnosticians. We also presented this objective at Plant Health 2021 at a virtual poster session and conducted an informal “pre-survey” in order to fine-tune the wording of the final survey questions. The survey was approved by the IRB. A second round of feedback on the survey was provided by diagnosticians attending the NPDN National Conference in April 2022 where I also presented this project and the "pre-survey" . By consulting with a diverse range of experts, we were advised to adapt our survey into a focus group. A focus group study was determined to be a more appropriate tool to address our objective and would provide more informative data compared to a survey. These activities have laid the groundwork for a more robust and informative focus group study.
Project Outcomes
The results of Objectives 1-4 will contribute to future sustainability efforts as we hope to learn more about population dynamics and evolutionary relationships between members of the Fusarium oxysporum Species Complex (FOSC). As this group contains endophytes, economically important plant pathogens, and biological control agents, it is important to know factors shaping these populations, specifically in vegetable production. Objective 5 will contribute to agricultural sustainability because we hope to provide resources that will aid in professional development goals of the National Plant Diagnostic Network (NPDN), thus strengthening this crucial service.
This project has provided a solid foundation to continue exploring the overarching goal of understanding the emergence of vascular wilt diseases in vegetables, particularly through characterizing nonpathogenic F. oxysporum associated with agricultural production. We were able to generate a substantial collection of F. oxysporum isolates that will continue to be evaluated in future studies. This project allowed us to optimize crucial approaches in isolating and maintaining F. oxysporum and evaluating tools to further characterize their behavior in planta.
Additionally, through Objective 5, our outreach component, we learned more about how Fusarium researchers can improve training materials to help plant diagnosticians as they serve growers. We plan to continue exploring this topic, and this project allowed us to receive informed feedback on the best approach to do so.