Nematologist Shahid Siddique of the UC Davis Department of Entomology and Nematology and his doctoral student Alison Coomer, drew widespread recognition at the Seventh International Congress of Nematology (ICN), held May 1-6 in Antibes Juan-Les-Pins, France. 

Siddique served as an invited speaker and chaired a nine-presentation session on nematode-plant interactions. He also was elected to the governing board member of the European Society of Nematology (ESN), and will serve a four-year term.

Siddique, who joined the UC Davis faculty in March 2019 as an assistant professor after serving as a research group leader for several years at the University of Bonn, Germany, delivered his address on “How Plants Recognize Nematodes: Signals and Signalling.”

Siddique focuses his research on "elucidating interactions between parasitic nematodes and their hosts using molecular and basic applied methodologies." Plant-parasitic nematodes are destructive pests causing losses of billions of dollars, he says on his lab website. "While these pests have been investigated mainly because they pose a major threat to food security globally, they are also intellectually fascinating due to their highly evolved interkingdom interactions with host plants." 

Coomer, who recently won a worldwide competition sponsored by the International Federation of Nematology Societies (IFNS) for her three-minute thesis on root-knot nematodes, presented her award-winning video, “Trade-Offs Between Virulence and Breaking Resistance in Root-Knot Nematode.”  She received a busary as well as a certificate signed by ICN president Larry Duncan of the University of Florida and conference chair Pierre Abad of France, a senior scientist at INRA, a French public research institute dedicated to agricultural science. Coomer also showcased her work on a life-sized poster. 

IFNS annually hosts the three-minute thesis competition “to cultivate student academic and research communication skills, and to enhance overall awareness of nematodes and the science of nematology.” Coomer, a doctoral student in plant pathology with an emphasis on nematology, is working on her dissertation, “Plant Parasitic Nematode Effectors and Their Role in the Plant Defense Immune System.”

The international meeting, themed “Crossing Borders: A World of Nematode Diversity and Impact to Discover" to reconcile the importance of agricultural production with that of environmental conservation,  drew 682 nematologists from 57 countries. Among them were 100 student and early career scientist busary recipients. The scientific program of 32 concurrent sessions included 288 oral presentations, 12 workshops, 12 keynote speakers and more than 500 poster presentations. 

It was the first in-person meeting in two years due to the COVID-19 pandemic. 

The nematode collection displayed at the 11th annual UC Davis Biodiversity Museum Day on Sunday, March 6 in the UC Davis Conference Center will feature mostly root-knot nematodes and Ascaris (roundworm) nematodes, according to nematologist Shahid Siddique, assistant professor, and doctoral student Alison Coomer. 

The display will include:

• What's in the jar?
• Celery infected with root-knot nematodes
• Tree swallow infected with Diplotriaena
• White-tailed deer eye infected with a Thelazia species
• Peach root infected with root-knot nematodes
• Mormon crickets infected with Gordius robustus
• Lettuce infected with root-knot nematodes
• Garlic damaged by Ditylenchus dipsaci
• Horse stomach infected with three parasites: Parascaris (roundworms), tapeworms, and botfly larvae.
• Grape roots infected with root-knot nematodes
• Sweet potato infected with root-knot nematodes
• Sugar beet infected with cyst nematodes
• Peach root infected with cyst nematodes
• Sugar beet infected with root-knot nematodes
• Ascaris lumbricoides (roundworm) 
• Minke whale infected infected with ascaridoid nematodes
• Heartworm of dog

Nematologist Steve Nadler, professor and chair of the UC Davis Department of Entomology and Nematology, explains what a nematode is on this YouTube video presented at the 2021 UC Davis Biodiversity Museum Day.

The event is set for 11 a.m. to 3 p.m. in the UC Davis Conference Center, 555 Alumni Lane. Admission and parking are free, but visitors must adhere to the COVID-19 Campus Ready guidelines. Masks will be required in accordance with campus policies, organizers said. Visitors can also sign up at the Conference Center for limited tours. Several museums or collections will be offering tours. (See news story)

"Plant-parasitic nematodes are destructive pests causing losses of billions of dollars annually," Siddique says on his website. "Economic, health, and environmental considerations make natural host plant resistance a preferred strategy for nematode control, but there are limitations to this approach. In many cases, the resistance conferred by resistance genes is partial, and some of the nematodes are able to survive. Similarly, nematode resistance genes are often effective against only one or a few species, whereas plants are exposed to several pathogens in the field. Another concern is the emergence of pathotypes that can overcome resistance. In view of all these limitations, it is important to identify additional mechanisms and tools that can be used to develop novel and sustainable approaches to the management of nematodes."

"Research in the Siddique lab focuses on basic as well as applied aspects of interaction between parasitic nematodes and their host plants," Siddique points out on his website. "The long-term object of our research is not only to enhance our understanding of molecular aspects of plant–nematode interaction but also to use this knowledge to provide new resources for reducing the impact of nematodes on crop plants in California."

Coomer, a second-year doctorate student, recently won a  worldwide competition  competition sponsored by the International Federation of Nematology Societies (IFNS) for her three-minute thesis on root-knot nematodes. She delivered her video presentation virtually on “Trade-Offs Between Virulence and Breaking Resistance in Root-Knot Nematodes.” She will be awarded a busary and plaque at the 7th  International Congress of Nematology (ICN), set May 1-6 in Antibes, France. 

Coomer earlier was selected one of the nine finalists in the 22-participant competition, vying against eight other graduate students from the University of Idaho, Moscow; and universities in England, Australia, Brazil, Ireland, Kenya, Belgium and South Africa. 

The UC Davis Biodiversity Museum Day is traditionally held on the Saturday of Presidents' Day weekend. However, last year's event was virtual, and this year's event is centrally located in an exposition. For more information, access the UC Davis Biodiversity Museum Day website and/or connect with Instagram,Twitter, and Facebook.

UC Davis second-year doctoral student Alison Coomer is now a global champion.

Coomer, a member of the laboratory of nematologist Shahid Siddique of the UC Davis Department of Entomology and Nematology, just won a world-wide competition sponsored by the International Federation of Nematology Societies (IFNS) for her three-minute thesis on root-knot nematodes.

She delivered her video presentation virtually on “Trade-Offs Between Virulence and Breaking Resistance in Root-Knot Nematodes.” She will be awarded a busary and plaque at the 7th  International Congress of Nematology (ICN), set May 1-6 in Antibes, France. 

Coomer earlier was selected one of the nine finalists in the 22-participant competition, vying against eight other graduate students from the University of Idaho, Moscow; and universities in England, Australia, Brazil, Ireland, Kenya, Belgium and South Africa. 

"Our entire lab is glad for Alison winning this award," said Siddique. "This is an outstanding performance and Alison has really been working hard for that. I feel proud about it. I am also looking forward to Alison's presentation at ICN."

Judges announced that Rhys Copeland of Murdoch University, Australia, won second, and Laura Sheehy of Liverpool John Moores University England,  scored third. They also will receive busaries and plaques at the 7th  International Congress of Nematology. (See the nine finalists' presentations on this site.)

Copeland discussed "Determining the Spatial Distribution of Pratylenchus quasitereoides/Pratylenchus curvicauda in the WA Wheatbelt, and Understanding How They Find Host Roots."

Sheehy's topic: Improving the Biological Control of Slugs: Understanding the Genome of Parasitic Nematode Phasmarhabditis hermaphrodita."

IFNS hosts the competition, IFNS 3-Minute Thesis, "to cultivate student academic and research communication skills, and to enhance overall awareness of nematodes and the science of nematology."

The competition began with 22 participants. Each was required to present only a single static slide, and not use any props or sound-effects. In the finals, a panel of judges--six nematologists and three non-experts from other areas of plant sciend science--scored them on the quality of their research presentation, ability to communicate research to non-specialists, and the 3MT slide. 

In her presentation, Coomer began with: “Root-knot nematodes, specifically the MIG-group, consisting of Meloidogyne incognita, javanica, and arenaria, are the most damaging of the plant parasitic nematodes causing severe yield loss in over 2,000 different plant species including tomatoes. The Mi-gene, which is a resistance gene in tomato, has been used in commercial farming and has been praised for its effectiveness towards the MIG group. This gene has been cloned but the mechanisms of how it's resistance works is still unknown.” 

“We do know that with the presence of the MI gene, plants are more durable and will restrict infection and reproduction, by inducing an immune response within the plant,” Coomer pointed. “Although this resistance gene has been reliable for many decades, resistance breaking strains of root-knot nematodes have emerged threatening the tomato industry.” 

Coomer related that her research “compares two strains of the root-knot nematode M. javanica. One strain is the wildtype, which has been isolated from fields, we will refer to it as VW4. This nematode can infect tomato plants, but when the MI gene is present, the nematode is blocked from successfully infecting. The other strain is a naturally mutated version of VW4. This strain breaks the resistance provided by the MI gene and therefore infects plants that contain the MI gene. I have labeled this strain as VW5. With the help of research like mine we can stay ahead of the resistance breaking strains and prevent major crop loss in the future.” 

“Sequencing the entire genome of VW5 when compared to VW4, we can see that there is a large deletion in its genome, but we have yet to find out what genes were deleted and how important they are when it comes to infecting other plants,” she continued. “My research is focusing on what happens when we infect the resistance breaking strain, VW5 on plants not containing the MI gene.” 

In detailing her research, she said “My infection assays have been designed as displayed by the flow chart. Tomato and cucumber were used since neither variety contained the MI gene. 500 J2s were inoculated and at 34 days post inoculation, roots were harvested, and eggs were collected. After staining, galls were dissected, and nematode stage development was recorded for juveniles and females; comparisons between the two roots were made. As displayed by the graph and image, consistently, we see a reduction in the number of eggs produced in plants infected with VW5 than with VW4. The image also shows significant reduction in galls for VW5s as well. Two main objectives remain for this project: How does VW5 break MI resistance and why is VW5 less fit on plants that do not contain the MI gene. With the help of further infection assays and genomic data regarding gene presence and transcription analysis we hope to shed light on this process, identify candidate genes in action, and overall identify how the mechanism of the MI gene works.”

Coomer, a doctoral student in plant pathology with an emphasis on nematology and advised by Siddique, is working on her dissertation, "Plant Parasitic Nematode Effectors and Their Role in the Plant Defense Immune System."

Coomer, originally from the St. Louis, Mo., area, received two bachelor degrees--one in biology and the other in chemistry--in May 2020 from Concordia University, Seward, Neb., where she won the Outstanding Graduate Student in Biology Award. She served as a biology lab assistant and taught courses in general biology and microbiology. 

As a biological science aide/intern, Coomer did undergraduate research in the Sorghum Unit of USDA's Agricultural Research Service. Lincoln, Neb.  Her work included collecting, prepping and analyzing DNA, RNA and proteins to identify genes that contribute to an under- and over-expression of lignin in sorghum plants.