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ARS Home » Northeast Area » Washington, D.C. » National Arboretum » Floral and Nursery Plants Research » Research » Publications at this Location » Publication #335367
Title: Cytological changes of Easter lily (Lilium longiflorum) upon root lesion nematode (Pratylenchus penetrans) infection

Author
item VIEIRA, PAULO - Virginia Tech
item Mowery, Joseph
item KILCREASE, JAMES - Orise Fellow
item EISENBACK, JONATHAN - Virginia Tech
item Kamo, Kathryn

Submitted to: Nematology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/15/2017
Publication Date: 3/1/2017
Citation: Vieira, P., Mowery, J.D., Kilcrease, J., Eisenback, J.D., Kamo, K.K. 2017. Cytological changes of Easter lily (Lilium longiflorum) upon root lesion nematode (Pratylenchus penetrans) infection. Plant Pathology. 49:1-11.

Interpretive Summary: Lilium longiflorum cv. Nellie White, commonly known as Easter lily, is an important floral crop with an annual wholesale value of over $26 million in the U.S. The root lesion nematode (RLN), Pratylenchus penetrans, is a major pest of lily due to the significant root damage it causes. In this study we investigated nematode infection using an in vitro culture method to multiply Easter lilies and then to follow the nematode activity for 60 days. We found that a major feature of the lily response to nematode infection was the formation of necrosis, browning, and tissue death involving both root epidermis and cortical cells. Degradation of cell walls resulted in collapse of the infected cells, followed by cell death along the intracellular path of the nematode’s migration. Nematodes were never seen in the vascular cylinder as the layer of collapsed endodermal cells presumably blocked the progression of P. penetrans into this area of the roots. This study presents the first detailed cytological characterization of P. penetrans infection of Easter lily plants and will provide both scientists and growers with a better understanding of the process involved in root lesion nematode infection of flower bulb crops.

Technical Abstract: Lilium longiflorum cv. Nellie White, commonly known as Easter lily, is an important floral crop with an annual wholesale value of over $26 million in the U.S. The root lesion nematode (RLN), Pratylenchus penetrans, is a major pest of lily due to the significant root damage it causes. In this study we investigated the cytological aspects of this plant-nematode interaction using bright-field light and transmission electron microscopy. We took advantage of an in vitro culture method to multiply lilies and follow the nematode infection over time. Phenotypic reactions of roots inoculated with P. penetrans were evaluated from 0 to 60 days after nematode infection. Symptom development progressed from initial randomly distributed discrete necrotic areas to advanced necrosis along entire roots of each inoculated plant. The induction and severity of symptoms could be correlated with the number of nematodes found parasitizing roots. A major feature characterizing this susceptible-host response to nematode infection was the formation of necrosis, browning, and tissue death involving both root epidermis and cortical cells. Degradation of consecutive cell walls resulted in loss of cell pressure, lack of cytoplasmic integrity, followed by cell death along the intracellular path of the nematode’s migration. RLN were never seen in the vascular cylinder as the layer of collapsed endodermal cells presumably blocked the progression of P. penetrans into this area of the roots. This study presents the first detailed cytological characterization of P. penetrans infection of Easter lily plants.