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3.  Effects of Temperature on the Fine-Structural Responses in the Hypocotyl Region of Alfalfa Lines to Ditylenchus dipsaci 
Journal of Nematology  1975;7(3):239-246.
Fine-structural analyses were made of the response of host tissue, Medicago sativa L. 'Ranger' and 'Lahontan', to infection by the stem nematode, Ditylenchus dipsaci (Kühn) Filipjev. Seedlings were grown at 15 and 25 C, and hypocotyl regions were sampled 1,3, or 7 days after inoculation. Electron micrographs of infected alfalfa tissue indicated that the same types of damage were inflicted on Lahontan (stem-nematode-tolerant)and Ranger (stem-nematode-susceptible). Only the infection rate and degree of damage differed between lines and temperatures, with the greater injury occurring at the higher temperatures. After 3 and 7 days of infection, the symptoms observed were: swollen and broken endoplasmic reticulum (ER), distended and broken chloroplasts, loss of nuclear material, and bulging and rupturing of nuclear envelopes. Cells with infected cytoplasm contained more ER, ribosomes, vesicles, and Golgi apparatuses, suggesting increased metabolic activities. Lobing nuclei were observed in all samples. Lipid contents varied with temperature in I-day-old seedlings. At 15 and 25 C, electron-dense substrances were commonly found along the tonoplast, and on the cell wall. Also, some cells with enlarged ER were noted in the noninfected controls at these temperatures.
PMCID: PMC2620109  PMID: 19308164
electron microscopy; host-parasite interactions
4.  Ultrastructure Changes Induced by Stem Nematodes in Hypocotyl Tissue of Alfalfa 
Journal of Nematology  1973;5(3):165-173.
Scarified seeds of Medicago sativa L. 'Ranger' and 'Lahontan' alfalfa were allowed to imbibe water for 36 hr and then were inoculated with stem nematodes, Ditylenchus dipsaci Kühn. Seedlings were grown in sterilized Provo sand at 20 C and hypocotyl sections harvested at 1, 3 and 7 days. Evidence from electron micrographs indicated that cells of noninfected control plants contained normally developing chloroplasts bearing stroma, thylakoids, starch grains and plastoglobuli. The cytoplasm contained a nucleus, endoplasmic reticulum, vacuoles, mitochondria, ribosomes and dictyosomes. No morphological symptoms of nematode infection were observed in infected plants of either Ranger of Lahontan alfalfa 1 day after inoculation. Electron micrographs of tissue from the infected plants, however, indicated more osmiophilic bodies (lipid bodies) per cell than did the noninfected control, with more lipid bodies present in Ranger than in Lahontan. Three and 7 days after planting, swollen hypocotyls could be seen; the degree of swelling was greater in Ranger than in Lahontan. Electron micrographs of infected tissues indicated that both cultivars were undergoing the same kind of damage. Injured organelles were endoplasmic reticulum, chloroplasts and the nucleus. Histochemical staining indicated no changes in the middle lamellae.
PMCID: PMC2620006  PMID: 19319326
fine structure; host-parasite interactions

Results 1-4 (4)