Thursday, October 2, 2014

"Root-Knot Nematode" Meloidogyne incognita

Tori Pilger
Meloidogyne incognita
"Root-Knot Nematode"

Picture from Erwin Rose and Hein Overmars


Domain: Eukaryota
Kingdom: Metazoa
Phylum: Nematoda
Family: Meloidogynida
Genus: Meloidogyne
Species: incognita
(Singh, 2012)

Female compared to male body shape
Photo courtesy of A&T University
Physical Description: The nematode Meloidogyne incognita, or more commonly known as the root knot nematode, is a plant parasite. Because it is a plant based parasite, it has a stylet that is hollow and protrusible. This stylet secretes digestive proteins into a cell that come from their dorsal and esophageal glands (Huang et al. 2003). The stylet then sucks up the remains of the root cell into the nematode itself. It does this by using a pump-like organ at the end of a long tube that is attached to the stylet. The cutical of the male nematode is ringed. It has no lips, and its tail is blunt. The female nematode is swollen and lemon-shaped.

The root knot nematode prefers subtropical conditions with large biomass (Devran, 2009). They are found throughout the world and affect over 2,000 species of plants. This nematode is critical in the agricultural business since it is the cause of most concern when dealing with parasites that can affect ground for generations. It is of most concern when dealing with small grains, fruits, tubers, vegetables, and turf grasses (Riedel, N/A). Once an area of land is infected with this nematode, there is little one can do about getting rid of it. There are no real natural predators for this specific nematode and thus it can be nearly impossible to get rid of. Therefore it is important to discover an infection of nematodes early on by checking for stunted plant growth, discoloration, reduction of fruit/vegetable/tuber/leaf number or any other sign that might indicate plant malnourishement (Krueger, 2008). The root creates these galls or root knots where the nematode has infected the plant. These areas are caused by the female nematodes. While in the juvenile state the nematode is free living and will move about the soil until it reaches a root. The females will then latch onto the root and remain stationary. The root will grow cells around the nematode and create what is called 'giant cells' which then form the gall of the infected root (Krueger, 2008).

Interesting facts: The common name 'root-knot nematode refers to the knotted look the roots get when infected by this parasite.
Very little is actually known about how the nematode digests its food. Many of the proteins it secretes are unknown compounds that are still being studied (Devran, 2009).
This nematode was first discovered in 1855 when it was infecting the plants of a greenhouse in England (Riedel, N/A).
When cut into, an infected gall on a root will either appear purple or grey/brown in color. The purple shows an active colony of nematodes whereas a grey or brown color shows a dead one (Krueger, 2008). 


Devran, Zubeyir; Sogut, Mehmet. (June, 2009). Journal of Nematology. Distribution and Identifictaion of Root-Knot Nematodes from Turkey. Retrieved from: Pg. 1, 4. 

Huang, Guozhong; Gao, Bingli; Maier, Tom; Allen, R.; Davis, Eric; Baum, Thomas; Hussey, Richard. (Nov. 1, 2002). A Profile of Putative Parasitism Genes Expressed 
in the Esophageal Gland Cells of the Root-knot Nematode Meloidogyne incognita.Retrieved from: Pg. 1, 4.

Krueger, Romy; McSorley, Robert. (January 2008). Nematode management in Organic Agriculture. Retrieved from: Pg. 1-2.

Riedel, Richard; Miller, Sally; Rowe, Randall. (N/A). Extension Factsheet. Root Knot Nematode. Retrieved from: Pg. 1.
Singh, Sunil. (April 2012). Pathogen of the Month. Meloidogyne incognita. Retrieved from: Pg. 1.

1 comment:

  1. So, the picture of the nematode at top must be of a male?