SEP 30, 2015 1:00 PM PDT

Plant Parasites Mimic Plant Hormones to Cause Disease

WRITTEN BY: Sarah Hertrich
Plant parasitic nematodes, such as the well-known root-knot nematode and the cyst nematode, invade plant roots near the root tip and enter the plants vascular system where they feed on the plant for several weeks. Symptoms in plants are quite dramatic and are typically associated with the formation of large “knots” or cysts. Severe infections result in reduced crop yield and deformities which decreases consumer acceptability of many vegetables. For example, carrots infected with root knot nematodes will undergo severe forking with knots forming primarily in the lateral roots.
Carrots infected with root knot nematodes will undergo severe forking.

It is not well understood how these parasites transform plant root cells into highly active feeding sites however; it is generally assumed that nematodes manipulate production and signaling of the plant hormone cytokinin. In addition, it is not known whether the hormone is secreted into host plants and its role in parasitism remains unknown. In plants, cytokinin regulates numerous developmental and physiological responses including cell division, tissue establishment, root growth, branching, senescence, seed germination and stress responses. It is hypothesized, that because knot formation in plants involves reentry of cells at some point during cell cycle, that cytokinin has a role in this aspect of pathogenesis.

Researchers from the University of Missouri as well as University of Bonn in Germany analyzed the activation of the hormone cytokinin during infection of plant model, Arabidopsis thaliana, and the cyst nematode, Heterodera schachtii. The researchers used interfering RNA (RNAi) to silence the HsIPT gene in H. schachtii, which contributes to cytokine synthesis in the parasite and inoculated it onto plants to see if it could cause infection. On plants that were infected with HsIPT mutants, susceptibility to disease was significantly decreased. This allowed the researchers to identify HsIPT as the gene responsible for the ability of H. schachtii to synthesize the functional plant hormone cytokinin. Secretion of this hormone allows the parasite to manipulate the plant host system to establish a long-term parasitic interaction.
Cytokinin regulates numerous developmental and physiological responses in plants.

While the IPT gene, responsible for the expression of isopentenyltransferase, has been found in other bacteria and fungi, this is the first report of the gene being found in an animal. This study provides the first genetic evidence of cytokinin synthesis by an animal that helps the parasite to induce and maintain a long-term parasitic interaction. Further investigation of this relationship may lead to future developments pesticides or biocontrol targets against root knot nematodes.

Sources: PNAS, American Phytopathological Society, Science Daily
 
About the Author
PhD
I am a postdoctoral researcher with interests in pre-harvest microbial food safety, nonthermal food processing technologies, zoonotic pathogens, and plant-microbe interactions. My current research projects involve the optimization of novel food processing technologies to reduce the number of foodborne pathogens on fresh produce. I am a food geek!
You May Also Like
OCT 17, 2022
Microbiology
Is it pan-resistant Candida auris? Now you can know for sure
OCT 17, 2022
Is it pan-resistant Candida auris? Now you can know for sure
Candida auris is a global concern, categorized by the CDC as an Urgent Threat level. According to the CDC's latest 2 ...
OCT 14, 2022
Microbiology
How Exactly do Bacteria Move? An Old Question is Finally Answered
OCT 14, 2022
How Exactly do Bacteria Move? An Old Question is Finally Answered
Bacteria are single-celled organisms, and while we know they can move around with filaments, the exact mechanisms behind ...
OCT 14, 2022
Chemistry & Physics
The Precursor to ATP
OCT 14, 2022
The Precursor to ATP
  Adenosine triphosphate (ATP) is the essential energy molecule that drives our bodies. The cleavage of one of its ...
OCT 28, 2022
Immunology
A Mysterious Molecule That Enables Viruses to Overcome Immunity
OCT 28, 2022
A Mysterious Molecule That Enables Viruses to Overcome Immunity
Viruses can infect many different kinds of cells, and those cells can often react directly to the infection. When bacter ...
NOV 10, 2022
Microbiology
TB Germ That Can Move to the Bones Resembles Ancient Strain Found in Mummies
NOV 10, 2022
TB Germ That Can Move to the Bones Resembles Ancient Strain Found in Mummies
Mycobacterium tuberculosis is the pathogenic bacterium that causes TB, which is still a major public health problem in m ...
NOV 29, 2022
Drug Discovery & Development
75g Kale Per Day Could Keep Bone Fractures Away
NOV 29, 2022
75g Kale Per Day Could Keep Bone Fractures Away
Vitamin K1- a nutrient found in leafy greens like kale, cabbage, and spinach- may help reduce bone fracture risk in elde ...
Loading Comments...