Progress 09/15/06 to 08/31/10

Outputs
OUTPUTS: We have accomplished all the objectives proposed. 1) Generated genomic resources for two important soil-borne fungal pathogens: Verticillium dahliae and Verticillium albo-atrum. These resources include:a 7X V. dahliae genome assembly integrated with an optical map; a 4X V. albo-atrum genome assembly; automated annotation results for both assemblies; and 20,000 Expression Sequence Tags (ESTs) from two V. dahliae cDNA libraries. 2) Conducted comparative analysis with V. dahliae and V. albo-atrum. 3) Broadened the impact of the project by integrating educational and mentoring activities through established outreach programs as well as initiating outreach to the growers and producers to enhance their understanding of the biology and control of diseases caused by Verticillium spp. The data were released through the Verticillium comparative web site (http://www.broadinstitute.org/annotation/genome/verticillium_dahliae /MultiHome.html). Multiple data releases, a comparative genomic manuscript (submitted to PLoS Pathogen) and a manuscript that describes the transposable elements and their relationship to pathogenicity were produced directly under this project (see publication list below). The availability of the genome sequence enabled rapid and reliable identification of V. dahliae cDNA sequences in a study of cDNA subtraction libraries that were derived from infected plant tissue. Comparative analyses of the genomes of races 1 and 2 of V. dahliae is underway using the sequenced race 2 strain, as well as analyses of mating type genes in Verticillium species. Additional work has included an in depth examination of the Verticillium dahliae secretome by sequence characteristics. Gene knockout experiments were initiated in V. dahliae to examine the roles of multiple genes that were identified as conserved among V. dahliae, V. albo-atrum, and another fungal wilt pathogen. PARTICIPANTS: Li-Jun Ma: Broad Institute of MIT and Harvard; Katherine F. Dobinson: Agriculture and Agri-Food Canada; Scott Evan Gold: University of Georgia; Seogchan Kang: Penn State University; Steven J. Klosterman: USDA-ARS; Krishnamurthy Subbarao: University of California Davis; Paola Veronese: North Carolina State. TARGET AUDIENCES: Multiple research projects were developed based on the genomic information. To carry out the outreach objectives of the grant, a hands-on workshop was delivered to teachers of the Salinas Union High School district, in Salinas, California by Drs Klosterman and Subbarao. The workshop was held in June, 2009. Teachers were introduced to the rationale for sequencing fungi of agricultural importance, the fungal genome initiative, and USDA AFRI (formerly NRI). Workshop attendees were introduced to the basic local alignment search tool, and protein or DNA sequence conservation between fungi and other organisms. Then the teachers applied some of this background knowledge using DNA and protein sequence information at the Verticillium Group website maintained by the Broad Institute, and the National Center for Biotechnology database. In additon, Dr. Veronese organized a 10-week research program for the undergraduate students Olivia Campbell (NCSU, Microbiology and Honors Program) and Crystal Phelps (Rhodes College, Biology) in summer 2007 and Amarpreet Kaur (NCSU, Biochemistry and Honors Program) and Lindsey Montefiori (NCSU, Microbiology) in 2008. The four students received training on basic principles and methods of molecular genetic analysis of Arabidopsis-Verticillium spp. interactions and had the opportunity to present results of their activity at the NCSU Undergraduate Summer Research Symposium held at the J. S. McKimmon Center on August 2, 2007 and July 31, 2008, respectively. For their work in Veronese's lab, Olivia Campbell and Amarpreet Kaur received the NCSU Honors Program Undergraduate Award for Creative and Research Projects. Drs. Steve Klosterman and Krishna Subbarao hosted a visit of plant physiology students from the University of California Santa Cruz to discuss aspects of Verticillium wilt research and the genome project funded through USDA-CSREES at USDA ARS station in Salinas. We also continually update the vegetable and small fruit industries in California regarding the progress in the sequencing project through oral presentations to the California Leafy Greens Board twice a year and to the California Strawberry Commission on an annual basis. PROJECT MODIFICATIONS: Not relevant to this project.

Impacts
Vascular wilts are chronic, and very often severe plant diseases that cause billions of dollars in annual crop losses. The specific findings resulting from this study include the discoveries of: 1).Among all sequenced eukaryotic genomes only those of three vascular wilt fungi, V. dahliae, V. albo-atrum, and F. oxysporum encode a homolog of a bacterial glucosyl transferase with known roles in bacterial pathogenicity, and specifically in the synthesis of osmoregulated periplasmic glucans. The acquisition of these genes through horizontal transfer events from bacteria in the order Rhizobiales likely contributed to the adaptation of vascular wilt fungi to live within the plant xylem vessels since the vessel fluid can undergo fluctuations in osmolarity. 2). The Verticillium genomes encode a diverse array of carbohydrate active enzymes and more pectin degrading enzymes than all other fungal genomes examined, suggesting an extraordinary capacity to degrade pectin present in the plant cell walls during penetration and during colonization of xylem vessels. 3). The comparison between two closely related Verticillium genomes revealed the existence of the flexible genomic regions in V. dahliae, defined as "genomic islands". These genomic islands are enriched for transposable elements, containing duplicated genes and genes that encode predicted proteins important in signaling/transcriptional regulation and iron/lipid metabolism. Coupled with the impressive arsenal of plant cell wall-degrading enzymes, the genomic islands may further contribute to the increased genetic plasticity observed in V. dahliae. The rich and high quality genomic resources generated through this project have accelerated efforts of scientists worldwide to understand the genetic basis of pathogenicity in these species. Particularly, our study reveals insights into the mechanism of niche adaptation of this group of agriculturally important plant pathogens, and sheds light on potential avenues for the development of novel disease management strategies to combat destructive vascular wilt diseases.

Publications

• Klosterman, S., Anchieta, A., Maruthachalam, K., Hayes, R., Subbarao, K., lettuce genes differentially expressed in a lettuce-Verticillium dahliae interaction. 10th International Verticillium Symposium, Corfu Island, Greece, November, 2009
• Klosterman, S., K. Subbarao, P. Veronese, K. Dobinson, S. Gold and S. Kang, L.-J. Ma. The Verticillium Comparative genomics understanding pathogenicity and Diversity American Phytopathological Society, Portland, OR, August 2009
• Klosterman S., K. V. Subbarao, S. Kang, S. E. Gold, P. Veronese, B. Thomma, Z. Chen, B. Henrissat, Y.-H. Lee, L. Park, M. Garcia-Pedrajas, Dez J. Barbara, A. Anchieta, R. de Jonge, P. Santhanam, K. Maruthachalam, Z. Atallah, S. Amyotte, Z. Paz, P. Inderbitzen, R. Hayes, D. Heiman, S. Young, Q. Zeng, R. Engels, J. Galagan, C. Cuomo, K. F. Dobinson, L.-J. Ma*. 2010. Verticillium comparative genomics yields insights into niche adaptation by plant vascular wilt pathogens. PLoS Pathogen (in preparation).
• Paz, Z, Garcia-Pedrajas, MD, Andrews, DL, Klosterman, SJ, Baeza-Montanez, L, Gold, SE. 2010. One Step Construction of Agrobacterium Recombination-ready plasmids (OSCAR), an efficient and robust tool for ATMT based gene deletion construction in fungi. Accepted (with minor revision), Fungal Genetics and Biology.
• Amyotte, S.G., P. Veronese , L.-J. Ma, S. Klosterman, and K.F. Dobinson. 2010. Transposable elements and the impacts on Verticillium genome evolution. (In preparation)
• Tan, X., et al., Ma, L.-J., Dobinson K.F.,Veronese, P. 2010 Genome-wide analysis of Class II transposons in phytopathogenic Verticillium spp.: biased distribution and evolution of lineage specific regions.
• One Step Construction of Agrobacterium Recombination-ready plasmids (OSCAR), an efficient and robust tool for ATMT gene deletion construction in fungi Z. Paz, S. E. GOLD, D. L. Andrews, S. J. Klosterman, M. D. Garcia-Pedrajas, L. Baeza-Montanez American Phytopathological Society, Charlotte, NC, August, 2010 Phytopathology 100:S98
• Klosterman, S.J., Veronese, P., Dobinson, K.F., Subbarao, K., Chen, Z., Anchieta, A., Maruthachalam, K, Paz Z., Heiman, D.I., Young, S., Zeng, Q., Engels, R., Koehrsen, M., Galagan, J., Birren, B., Cuomo, C., Kang, S., Gold, S.E., Ma, L-J. (2009) Verticillium comparative genomics understanding pathogenicity and diversity. Proceedings of the XXV Fungal Genetics Conference, Asilomar Conference Center, Pacific Grove (CA), March, 2009
• Amyotte, S.G., Dobinson, K.F., Veronese P., Klosterman, S.J., Subbarao, K.V., Gold, S. Kang, S.E., Ma, L.-J. (2009) Transposable elements in Verticillium dahliae and V. albo-atrum. 10th International Verticillium Symposium, Corfu Island, Greece, November, 2009
• Santhanam, P., de Jonge, R., Thomma, B. (2009) Identification of the Verticillium dahliae secretome by sequence characteristics. 10th International Verticillium Symposium, Corfu Island, Greece, November, 2009
• Klosterman, S. J., Subbarao, K., Dobinson, K. F., Veronese, P., Thomma, B. P. H. J., Garcia-Pedrajas, M. D., Anchieta, A., Chen, Z., Barbara, D., De Jonge, R., Santhanam, P., Maruthachalam, K., Atallah, Z., Aymotte, S., Inderbitzin., P., Paz, Z., Heiman, D. I., Young, S., Zeng, Q., Engels, R., Koehrsen, M., Galagan, J., Birren, B., Cuomo, C., Kang, S., Gold, S. E., Ma L.-J. (2009) Verticillium comparative genomics: Understanding pathogenicity and diversity. X International Verticillium Symposium, Corfu Island, Greece, November 16-20, 2009, abs. 24
• Barbara, D., Inderbitzin., P., Clewes, E., Grant, C., Klosterman, S. J., Subbarao, K., Dobinson, K. F., Veronese, P., Thomma, B. P. H. J., Garcia-Pedrajas, M. D., Anchieta, A., Chen, Z., De Jonge, R., Santhanam, P., Maruthachalam, K., Atallah, Z., Aymotte, S., Paz, Z., Heiman, D. I., Young, S., Zeng, Q., Engels, R., Koehrsen, M., Galagan, J., Birren, B., Cuomo, C., Kang, S., Gold, S. E., Ma L.-J. (2009) Analyses of mating type genes in Verticillium species. X International Verticillium Symposium, Corfu Island, Greece, November 16-20, 2009, abs. 27
• Klosterman, S., K. Subbarao, P. Veronese, K. Dobinson, S. Gold and S. Kang,. L.-J. Ma. Comparative genomics of the plant vascular wilt pathogens, Verticillium dahliae and Verticillium albo-atrum. American Phytopathological Society, Charlotte, NC, August, 2010

Progress 09/15/08 to 09/14/09

Outputs
OUTPUTS: After the public releases of the genome assemblies of both Verticillium dahliae and V. albo-atrum through the Verticillium comparative web site (http://wwwdev.broad.mit.edu/annotation/genome/verticillium_group/), we have focus our studies in understanding the pathogenicity of Verticillium using comparative approaches. The global alignments reveal very high sequence identity (>92%) between these two selected Verticillium genomes, which ensures the unambiguous identification of orthologous genomic regions and highlights species-specific genomic regions on two chromosomes of Verticillium dahliae. These regions, containing 354 protein encoding genes, are enriched in certain DNA transposon sequences. The 354 genes in these regions are apparently of fungal origin, and approximately half of these share a paralog in Verticullium dahliae in non-lineage specific regions. Comparative analyses of proteins from V. dahliae with two other vascular wilt pathogens, Verticillium albo-atrum and Fusarium oxysporum, and other Fusarium species, have enabled the identification of 17 proteins that are only shared among the three wilt pathogens. These proteins may contribute to the unique lifestyle of these soilborne vascular pathogens. As a result of this finding, two researchers on the grant are currently cooperating to pursue gene disruption experiments of two of these genes in Verticillium dahliae. Detailed analyses of the carbohydrate-active enzymes of Verticllium dahliae and Verticillium albo-atrum, coupled with comparisons to other fungi, have revealed increased numbers of pectin degrading enzymes, which is particular relevance to the pathogenicity of these fungi. We also have identified enhanced numbers of carbohydrate binding module 1 (CBM1)-containing proteins in Verticillium dahliae relative to other fungi. Historically, CBM1s are referred to as cellulose binding domains, and these highly conserved domains bind cellulose from plant cell walls. Verticillium dahliae has a number of CBM1-enodong proteins that rival that of the dung fungus, Podospora anserina. V. dahliae and P. anserina each have a total of thirty of these types of proteins, the highest numbers of the sequenced ascomycete fungi. The numbers of these types of proteins are also elevated relative to other fungi in Verticillium albo-atrum. This finding may have significance in extending the host range of Verticillium species, since the breakdown of cellulosic substrates from a diverse array of plant hosts may require an enhanced arsenal of these types of proteins. This finding also raises additional questions about the saprophytic ability of Verticillium spp. PARTICIPANTS: Li-Jun Ma: Broad Institute of MIT and Harvard; Katherine F. Dobinson: Agriculture and Agri-Food Canada; Scott Evan Gold: University of Georgia; Seogchan Kang: Penn State University; Steven J. Klosterman: USDA-ARS; Krishnamurthy Subbarao: University of California Davis; Paola Veronese: North Carolina State. TARGET AUDIENCES: To carry out the outreach objectives of the grant, a hands-on workshop was delivered to teachers of the Salinas Union High School district, in Salinas, California by Drs Klosterman and Subbarao. The workshop was held in June, 2009. Teachers were introduced to the rationale for sequencing fungi of agricultural importance, the fungal genome initiative, and USDA AFRI (formerly NRI). Workshop attendees were introduced to the basic local alignment search tool, and protein or DNA sequence conservation between fungi and other organisms. Then the teachers applied some of this background knowledge using DNA and protein sequence information at the Verticillium Group website maintained by the Broad Institute, and the National Center for Biotechnology database. In additon, Dr. Veronese organized a 10-week research program for two undergraduate students. Drs. Steve Klosterman and Krishna Subbarao hosted a visit of plant physiology students from the University of California Santa Cruz to discuss aspects of Verticillium wilt research and the genome project funded through USDA-CSREES at USDA ARS station in Salinas. We also continually update the vegetable and small fruit industries in California regarding the progress in the sequencing project through oral presentations to the California Leafy Greens Board twice a year and to the California Strawberry Commission on an annual basis. PROJECT MODIFICATIONS: Not relevant to this project.

Impacts
Verticillium dahliae is the primary causal agent of Verticillium wilts that cause billions of dollars in annual losses worldwide. This soil-borne fungal pathogen exhibits extraordinary genetic plasticity and is able to rapidly adapt to a broad range of hosts in diverse ecological niches. Control of Verticillium wilt is particularly difficult, due to their persistence in the soil and the organisms' ability to adapt. The knowledge gained through this study, even at its early stages, already deepens our understanding of evolutionary mechanism involving the pathogens development and holds the promises for the development of novel control mechanisms. Of the particular interest is the discovery of a limited gene set that uniquely shared among three wilt pathogens sequenced, which may contribute to the development of novel strategies in disease management for these wilt pathogens.

Publications

• Klosterman S. and L.-J. Ma. Verticillium comparative genomics: understanding pathogenicity and diversity. APS Centennial meeting. 2008, St. Paul MN.
• Dobinson K.F. The molecular road from differentiation of Verticillium isolates to analysis of growth and development. 2008. APS Centennial meeting. 2008, St. Paul MN.
• Ma, L.-J., S. Klosterman, K. Subbarao, P. Veronese, K. Dobinson, S. Gold and S. Kang. 2007Verticillium Comparative genomics understanding pathogenicity and Diversity. Microbial Genome Sequencing Program Awardee Workshop. San Diego, January 2007.
• Klosterman, S., K. Subbarao, P. Veronese, K. Dobinson, S. Gold and S. Kang,. L.-J. Ma. 2007 Verticillium Comparative genomics understanding pathogenicity and Diversity. Fungal Genetic Conference, Asilomar, California, March 2007
• S.G. Amyotte, K.F. Dobinson, P. Veronese, S.J. Klosterman, K.V. Subbarao, S.E. Gold, S. Kang, L.-J. Ma. 2009 Transposable elements in Verticillium dahliae and V. albo-atrum APS meeting, August, 2009
• Klosterman, S., K. Subbarao, P. Veronese, K. Dobinson, S. Gold and S. Kang,. L.-J. Ma. 2009 The Verticillium Comparative genomics: understanding pathogenicity and Diversity APS. Portland, Oregon. August 2009
• Klosterman, S., K. Subbarao, P. Veronese, K. Dobinson, S. Gold and S. Kang,. L.-J. Ma. 2009 The Verticillium Comparative genomics: understanding pathogenicity and Diversity Fungal Genetic Conference, Asilomar, California, March 2009.

Progress 09/15/07 to 09/14/08

Outputs
OUTPUTS: In the past year, the Verticillium comparative project had made speedy progress. In February 2008, we publicly released the high quality 7.5 X genome assembly of V. dahliae and an optical map with ~300 X physical coverage that consists of 8 chromosomes. This initial release allows the users to: 1) do BLAST searches against our 7.5X genome assembly; 2) download the consensus sequence and additional files for the genome assembly; 3) Search and download a particular region of the genome assembly; 4) access the optical map of Verticillium dahliae and integration with the genome assembly; and 5) search genomic features including PFAM and RFAM domains, repeats, and ab initio gene predictions. In June 2008, we publicly released the Verticillium comparative web site (http://wwwdev.broad.mit.edu/annotation/genome/verticillium_group/). In addition to the V. dahliae assembly, this comparative web site provides the research community with windows to access the 4X assembly of V. albo-atrum, alignments of over 38,000 EST reads and the results of automated annotation for both genomes. 1) Using assisted assembly techniques, we were able to improve the assembly quality for the low coverage V. albo-atrum genome, resulting in an N50 scaffold of 2.32 Mb (half of the scaffolds in the assembly are greater than or equal to 2.32 Mb). 2) Automated gene annotation, using EST alignments as evidence produced 10,535 and 10,223 genes for V. dahliae and V. albo-atrum, respectively. We have publicly released the gene sets through both Broad comparative web page and the NCBI data bank. 3) The comparative search function built into the comparative web page allows the users to comparing the presentation of features such as PFAM domains, Blast homologs, and tRNAs. PARTICIPANTS: Not relevant to this project. TARGET AUDIENCES: Dr. Veronese organized a 10-week research program for two undergraduate students. The research opportunity was advertized within NCSU and all the instituitions who provided support letters for the outreach component of the Verticillium genome sequencing initiative. The participants were selected on the basis of their credentials (GPE and reference letters) and belonging to underepresented groups. The students acquired knowledge of principles and methods for the molecular genetic analysis of Arabidopsis-Verticillium spp. PROJECT MODIFICATIONS: Not relevant to this project.

Impacts
Verticillium dahliae is the primary causal agent of Verticillium wilts that cause billions of dollars in annual losses worldwide. This soil-borne fungal pathogen exhibits extraordinary genetic plasticity and is able to rapidly adapt to a broad range of hosts in diverse ecological niches. Control of Verticillium wilt is particularly difficult. One factor that has hindered progress in developing new control strategies for Verticillium wilt is our limited understanding of the biology and ecology of V. dahliae and other soil-borne pathogens. V. albo-atrum, another widespread and well-studied phytopathogenic Verticillium species, is closely related to V. dahliae, but has a very different host range and distinct phenotypes with respect to its pathogenicity. The genomic resources created through this project will fill the knowledge gap. We will apply comparative genomics to study the molecular mechanisms that underlie the differences in pathogenicity, differentiation, and host-adapted virulence in these two Verticillium spp.. Knowledge of the genome content of these two important soil-borne plant pathogens will greatly accelerate efforts of scientists worldwide to understand the genetic basis of pathogenicity, virulence, and niche adaptation in these species.

Publications

• Dobinson K.F. 2008, The molecular road from differentiation of Verticillium isolates to analysis of growth and development. APS Centennial meeting. St. Paul MN.Invited talk.
• Ma, L.-J., S. Klosterman, K. Subbarao, P. Veronese, K. Dobinson, S. Gold and S. Kang,. 2007, Verticillium Comparative genomics in understanding pathogenicity and Diversity. Microbial Genome Sequencing Program Awardee Workshop. San Diego. Poster presentations
• Klosterman, S., K. Subbarao, P. Veronese, K. Dobinson, S. Gold and S. Kang,. L.-J. Ma. 2007, Verticillium Comparative genomics in understanding pathogenicity and Diversity. Fungal Genetic Conference, Asilomar, California. Poster presentations
• Li-Jun Ma, et al. 2008. This Whole Genome Shotgun projects for both V. dahliae and V. albo-atrum have been deposited at DDBJ/EMBL/GenBank under the project accessions ABJE00000000 and ABPE00000000 respectively. The versions described in the current release, including both assemblies and annotations, are ABJE01000000 and ABPE01000000. The sequence traces from the Broad Institute sequencing can be downloaded from the NCBI trace repository.
• Klosterman S. and L.-J. Ma. 2008, Verticillium comparative genomics, understanding pathogenicity and diversity. APS Centennial meeting. St. Paul MN. Invited talk.

Progress 09/15/06 to 09/14/07

Outputs
In the first year of this two-year project, we have been working towards the completion of the first objective of generating genomic resources of V. dahliae and V. albo-atrum. In the process, we have developed a protocol to extract high quality genomic DNA specifically designed to deal with the high content of polysaccharides in the cell wall of Verticillium species. Using this protocol, high quality genomic DNA samples were prepared for whole genome shotgun sequencing. All the WGS libraries had been successfully created. Over 378,000 whole genome shotgun reads from Verticillium dahliae and 38,000 reads from V. albo-atrum have been deposited at the NCBI trace repository. At the same time, we have created an optical map for V. dahliae with ~300X physical coverage. The optical map reveals that the Verticillium daliae genome contains 7 chromosomes with a genome size of ~32 Mb. To assist the automated annotation, we have generated three cDNA libraries from three different cultural conditions including complete cultural medium, minimal medium nitrogen and the minimal medium containing the plant root extract. These cDNA libraries are in the queue to be sequenced. During summer 2007, Dr. Veronese organized a 10-week research program for two undergraduate students. The research opportunity was advertized within NCSU and all the instituitions who provided support letters for the outreach component of the Verticillium genome sequencing initiative. The participants were selected on the basis of their credentials (GPE and reference letters) and belonging to underepresented groups. The students acquired knowledge of principles and methods for the molecular genetic analysis of Arabidopsis-Verticillium spp. The results were presented at the Sixth Annual North Carolina State University Undergraduate Summer Research Symposium held on August 2 at the J.S. McKimmon Center.

Impacts
Verticillium wilts cause billions of dollars in annual losses worldwide. The causal agent of this severe disease is Verticillium dahliae, a soil-borne fungal pathogen that exhibits extraordinary genetic plasticity and is able to rapidly adapt to a broad range of hosts in diverse ecological niches. V. albo-atrum, another widespread and well-studied phytopathogenic Verticillium species, is closely related to V. dahliae, but has a very different host range and distinct phenotypes with respect to its pathogenicity. The comparative genomic resources created through this project will accelerate efforts of scientists worldwide to understand the genetic basis of pathogenicity, virulence, and niche adaptation in these species. Optical mapping is an enabling technology for whole-genome assembly, which involves the capture of individual chromosomal DNAs, followed by in situ digestion by selected restriction enzymes. Since no genetic map is available for V. dahliae, the creation of an optical map provides an extremely valuable tool. The integration of the optical map and sequence assembly will offer means to anchor sequence scaffolds to the chromosomes and provide a comprehensive landscape of the genome structure.

Publications

• Klosterman, S.J. 2007. Isolation of high molecular weight DNA and direct PCR from Verticillium spheroplasts. In preparation.
• Ma, L.-J., S. Klosterman, K. Subbarao, P. Veronese, K. Dobinson, S. Gold and S. Kang. 2007 (January). Verticillium Comparative genomics - understanding pathogenicity and Diversity. Microbial Genome Sequencing Program Awardee Workshop. San Diego
• Klosterman, K. Subbarao, P. Veronese, K. Dobinson, S. Gold and S. Kang,. L.-J. Ma. 2007 (March). Verticillium Comparative genomics - understanding pathogenicity and Diversity. Fungal Genetic Conference, Asilomar, California
• Campbell O and P. Veronese. 2007 (August) . Microarray analysis of Arabidopsis genes induced during colonization with the vascular fungal pathogen Verticillium dahliae . Sixth Annual North Carolina State University Undergraduate Summer Research Symposium. NCSU, Raleigh, NC
• Crystal Phelps C. and P. Veronese. 2007 (August) .Functional analysis of gene network regulating Arabidopsis responses to colonization with the vascular fungal pathogen Verticillium dahliae. Sixth Annual North Carolina State University Undergraduate Summer Research Symposium. NCSU, Raleigh, NC