- Author: Kathy Keatley Garvey
And UC Davis plant nematologist Shahid Siddique, formerly with the University of Bonn, is at the heart of it.
He led a 10-member international team in discovering the role of a plant's endodermal barrier system in defending against plant-parasitic nematodes.The Plant Journal published the research, Root Endodermal Barrier System Contributes to Defence against Plant‐Parasitic Cyst and Root-Knot Nematodes, in its July 19th edition.
Fast forward to October.
Research Highlight Editor Lysa Maron chose the work as the "research highlight" in her Oct. 14th article, “Breaking or Sneaking into the Fortress: the Root Endodermis is a Defence Wall Against Nematode Infection.” The journal also showcased the team's nematode image on the cover.
What's the significance of the research?
“We discovered that the integrity of the endodermis—a specialized cell layer that surrounds the vascular system and helps regulate the flow of water, ions and minerals--is important to restrict nematode infection,” said Siddique, an assistant professor in the UC Davis Department of Nematology who joined the faculty in March after serving several years at the University of Bonn.
“We found that having defects in endodermis make it easier for parasites to reach the vascular cylinder and establish their feeding site. Although, this finding is a result of basic research, it opens new avenues to for breeding resistance against cyst nematodes in crops.”
Maron noted that “Roots are a truly amazing plant structure: they conquer the underground, form complex structures that anchor the plant, let water and nutrients in, but must not dry out. Roots store energy, send signals to the aboveground parts of the plant and to neighbors, and defend the plant against soil-borne pathogens. Within the root, the endodermis is the barrier that separates the inner vasculature from the outer cortex. If the root is a fortress, the endodermis is the gated wall. Cell wall reinforcements such as the casparian strip (CS), lignin deposition, and suberin seal the apoplast of the endodermis throughout different parts of the root. These reinforcements allow the diffusion of water and nutrients to and from the vascular tissue while blocking its penetration by pathogens such as bacteria and fungi (Enstone et al., 2002).”
“But roots also face pathogens of a different kind: root-infecting, sedentary endoparasites such as cyst nematodes (CNs) and root-knot nematodes (RKNs),” Maron wrote. “These pathogens infect a variety of important crops and cause significant yield losses (Savary et al., 2019).”
Maron quoted Siddique: “According to Siddique, investigating root traits that affect plant-nematode interactions is important for finding new strategies for plant protection. Screening for natural variation in suberin- and lignin-related traits might help identify and develop stronger fortresses, i.e., plants with enhanced resilience against pathogens, drought, and nutrient deficiency.”
Siddique collaborated with scientists from Germany, Switzerland and Poland: Julia Holbein, Rochus Franke, Lukas Schreiber and Florian M. W. Grundler of the University of Bonn; Peter Marhavy, Satosha Fujita, and Niko Geldner of the University of Lasuanne, Switzerland; and Miroslawa Górecka and Miroslaw Sobeczak of the Warsaw University of Life Sciences, Poland.
“Plant-parasitic nematodes are among the most destructive plant pathogens, causing agricultural losses amounting to $80 billion annually in the United States,” said Siddique in an earlier news story. “They invade the roots of almond, tomato, beets, potato or soybeans and migrate through different tissues to reach the central part—the vascular cylinder--of the root where they induce permanent feeding sites.”
“These feeding sites are full of sugars and amino acids and provide the parasite all the nutrients they need,” Siddique explained. “A specialized cell layer called the endodermis surrounds the vascular system and helps regulates the flow of water, ions and minerals into and out of it. However, the role of endodermis in protecting the vascular system against invaders such as nematodes had remained unknown.
The German Research Foundation funded the research.
- Author: Kathy Keatley Garvey
Schroeder will speak on "Endless Worms Most Beautiful" at 4:10 p.m. in Room 122 of Briggs Hall, off Kleiber Hall Drive. Plant nematologist and assistant professor Shahid Saddique of the Department of Entomology and Nematology will serve as the host. The event is open to all interested persons.
Schroeder's website indicates that he "makes new discoveries on the biology of nematodes, one of the world's most abundant group of animals. His work identifies how nematodes survive difficult environmental conditions, which helps control parasitic nematodes and reveals how higher animals like humans deal with stress."
"My laboratory studies the development and anatomy of diverse nematode species to understand the plasticity of structure within species and the generation of novel forms across evolution," Schroeder explains in his abstract. "Caenorhabditis elegans is a bacterial feeding nematode widely used as a model for understanding basic cellular and molecular processes. Under specific environmental stressors, C. elegans can enter a developmental switch into a stress-resistant dauer stage. During the entry to dauer, several tissues rapidly remodel. We discovered a new neuronal remodeling phenotype during dauer formation and have described several mechanisms controlling this phenotype."
"In addition to neuronal remodeling," he says, "C. elegans also undergoes remodeling of epithelial stem cell-like 'seam cells.' We have identified a group of extracellular proteins that regular the seam cell remodeling process. While C. elegants research is blessed with numerous tools, this nematode represents only one of thousands of species inhabiting wide-ranging aquatic and terrestrial habitats. Together with their relatively simple anatomy, nematodes are an ideal taxon to understand the evolution of anatomy."
Schroeder adds: "In addition to our work in C. elegans, we are exploring the mechanisms controlling new anatomical forms. For example, we recently found that the seam cell homologs in the cyst nematode Heterodera glycines have increased proliferative capacity compared with C. elegans. This increased cell division likely contributes to the atypical lemon-shape of H. glycines. Finally, we are beginning a collaboration with the NIH-funded WormAtlas to expand their offerings beyond C. elegans and help bridge the divide between the sometimes-disparate research communities."
Schroeder, who joined the Department of Crop Sciences in 2013, received his bachelor of science degree in chemistry from Earlham College, Richmond, Ind., in 1998, and his doctorate in plant pathology from the University of Wisconsin-Madison in 2008. He then served as a postdoctoral fellow in the Department of Genetics, Rutgers University, New Jersey, from 2008 to 2013.
Community ecologist and assistant professor Rachel Vannette is coordinating the seminars, which are held every Wednesday at 4:10 p.m. in 122 Briggs Hall. (See schedule.)
- Author: Kathy Keatley Garvey
And you ought to be interested in the exciting research that Shahid Masood Siddique, a new member of the UC Davis Department of Entomology and Nematology faculty, is doing.
Plant-parasitic nematodes are microscopic worms that extract water and nutrients from such host plants as wheat, soybeans, sugar beets, citrus, coconut, corn, peanuts, potato, rice, cotton and bananas. (See more from a list compiled by the Agricultural Research Services of the U.S. Department of Food and Agriculture or USDA-ARS.)
“They're one of the most destructive agricultural pests,” says Siddique, an assistant professor who joined the UC Davis Department of Entomology and Nematology last March. “The agricultural losses due to plant-parasitic nematodes reach an estimated $80 billion. The high impact of plant parasitic nematodes in economically important crops is not only due to the direct damage but also because of the role of some species as virus vectors.”
“In fact, a recent expert-based assessment of crop health lists nematodes among the most damaging pests and pathogens in different crops. In particular for soybeans, nematodes are the most damaging pests in the United States and around the world.”
Siddique, who served as a research group leader for several years at the University of Bonn, Germany, before joining the UC Davis faculty, says nematodes are troubling in other ways as well. “Although nematode-resistance varieties are available for various crops, there is an emergence of resistant-breaking population throughout the world. An example is the recent arrival of peach root-knot nematode in California, which has the potential to seriously harm many of region's important crops including almonds, peaches, eggplants, sugar beets and cucumber.”
Siddique was among a team of scientists from Bonn University and University of Missouri, who demonstrated the ability of parasitic nematodes to synthesize and secrete a functional plant hormone to manipulate the host system and establish a long-term parasitic interaction. PNAS published the research in August 2015. In a subsequent article headlined “Researchers Discover Key Link in Understanding Billion-Dollar Pests in Agriculture,” Science Daily called nematodes “a huge threat to agriculture, causing billions in crop losses every year …The discovery will help to develop crop plants that feature enhanced protection against this type of parasites.”
Born and reared in Multan, Pakistan, Siddique received two degrees in Multan: his bachelor of science degree from the Government College Bosan Road in 2001 and his master's degree in botany from the Bahauddin Zakariya University in 2004. Then it was off to Vienna, Austria to receive his doctorate in 2009 in agriculture and biotechnology from the University of Natural Resources and Life Sciences.
“His group was working on understanding the molecular aspects of plant-nematode interaction,” Siddique recalled. “In particular, they were using microarrays to study the changes in gene expression in plants upon nematode infection. I found the work very interesting and joined his lab.”
Nematodes did not immediately trigger his interest. “They have a complicated life cycle and infection pattern,” he points out. “Also, it is not yet possible to genetically transform plant-parasitic nematodes. So, I was mostly focusing on plants, which are more amenable to genetic manipulations. Then I gradually started to realize that how fascinating it is to work with nematodes, how they have mastered the ability to manipulate the defense and developmental pathways of their host.”
By the time he completed his doctorate, “I was completely infected by nematodes.” He still is.
What drew him to UC Davis? “High academic reputation in field of agriculture was the main factor that drew me to UC Davis,” Siddique says. “Ethnic diversity and liberal culture of golden state are some of the other factors that contributed to my decision to move to UC Davis.”
“For the next six months, I will be focusing on establishing a state-of-the art nematology lab here at UC Davis. This includes buying equipment, hiring the staff, establishing the protocol, and multiplying the nematode culture. In terms of research, my mid-term goal is understanding the plant immune responses to nematode infections. In long-term, I would like to use this knowledge to produce durable and broad-spectrum resistance in crops.”
“Another area where I will be focusing is development of molecular diagnostic tools for plant-parasitic nematodes from soil,” Siddique says. “I will be particularly focusing on nematodes that are relevant to California agriculture. Lastly, I am highly interested in understanding the mechanism of biocontrol of plant-parasitic nematodes. I expect that this will help in understanding why application of microbial biocontrol is so inconsistent.”
Siddique describes himself as “a result-oriented person and I am comfortable leading a large research team. At the same time, I like to delegate the responsibilities. My working style is collaborative and I believe on open and frank communication.”
In his leisure time, he enjoys cooking, outdoor adventures and watching documentaries. What would people be surprised to know about him? “I am an introvert,” he says. “A couple of other things: I like super spicy food and my favorite game is cricket. And oh, yes, I don't like ice-cold water.”
Siddique is currently seeking “undergraduate and graduate students to work on a number of exciting projects.”
“California is a beautiful place to live,” Siddique says, “and Davis is a perfect place to work on nematodes. So, for those interested in working with nematodes, drop me an email at ssiddique@ucdavis.edu.”
Related Links:
- “Worm Subverts Plant Attack,” The Scientist, April 3, 2014
- “Researchers Discover Key Link in Understanding Billion-Dollar Pests in Agriculture,” Science Daily, Sept. 29, 2015
- “Arabidopsis Leucine-Rich Repeat Receptor–Like Kinase NILR1 Is Required for Induction of Innate Immunity to Parasitic Nematodes,” PLOS Pathogens, April 13, 2017
