Characterization of the Early Host-nematode Relationship of Meloidogyne Incognita Infecting Resistant and Susceptible Alfalfa Cultivars

Persistent Link:
http://hdl.handle.net/10150/195802
Title:
Characterization of the Early Host-nematode Relationship of Meloidogyne Incognita Infecting Resistant and Susceptible Alfalfa Cultivars
Author:
Flores-Lara, Yolanda
Issue Date:
2005
Publisher:
The University of Arizona.
Rights:
Copyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.
Abstract:
Plant parasitic nematodes cause billons of dollars in annual crop losses. One of the most damaging is the root-knot nematode, Meloidogyne incognita, which is known to attack more than 3000 plants. This research will contribute to the understanding of host-plant resistance through characterization of the early infection processes of Meloidogyne incognita race 3 in susceptible (Lahontan) and resistant (Moapa) alfalfa cultivars by light microscopy and transmission electron microscopy. Neither differential penetration of M. incognita J2 into Lahontan, nor migration of J2 from Moapa, played a significant role in the resistance mechanism(s). Coiled nematodes in the cortex were observed in greater numbers in the Moapa 48 hours after inoculation. This position was interpreted as a sign of disorientation and starvation. By 96 hours after inoculation, no coiled nematodes were observed in Lahontan. In Moapa, resistance probably depends not only on the failure of the J2 to identify a suitable feeding site and initiate giant cells, but also on its inability to maintain the giant cells, once they are initiated. At the ultrastructural level, 48 hours after inoculation, the most evident change in both cultivars was the appearance of a uniform interstitial material (IM) between the nematode cuticle and the root cell wall. At 96 hours, IM in Moapa was completely agglutinated while in Lahontan it was still uniform or only slightly agglutinated. Due to these clear differences between both cultivars I propose that the IM plays a role in the resistance of Moapa to M. incognita. Immunolabeling techniques were employed to determine if the distribution of the nematode's surface coat, deposited in host tissues, differs in resistant and susceptible alfalfa cultivars. At 72 hours after inoculation, labeling of surface coat epitopes in Moapa was stronger than at 24 and 48 hours after inoculation. Labeling was observed on the nematode's cuticle, the plant cell wall, and the IM. In Lahontan, 72 and 96 hours after penetration, labeling of the surface coat epitopes was observed on the nematode's cuticle, the root cell walls, and the cell wall junctions of cells near the nematode, but not in direct contact with the cell.
Type:
text; Electronic Dissertation
Keywords:
Meloidogyne incognita; Root-knot nematode; alfalfa resistance; Ultrastructural responses; Meloidogyne incognita surface coat; MISC nematode antibody
Degree Name:
PhD
Degree Level:
doctoral
Degree Program:
Plant Pathology; Graduate College
Degree Grantor:
University of Arizona
Advisor:
McClure, Michael A.
Committee Chair:
McClure, Michael A.

Full metadata record

DC FieldValue Language
dc.language.isoENen_US
dc.titleCharacterization of the Early Host-nematode Relationship of Meloidogyne Incognita Infecting Resistant and Susceptible Alfalfa Cultivarsen_US
dc.creatorFlores-Lara, Yolandaen_US
dc.contributor.authorFlores-Lara, Yolandaen_US
dc.date.issued2005en_US
dc.publisherThe University of Arizona.en_US
dc.rightsCopyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.en_US
dc.description.abstractPlant parasitic nematodes cause billons of dollars in annual crop losses. One of the most damaging is the root-knot nematode, Meloidogyne incognita, which is known to attack more than 3000 plants. This research will contribute to the understanding of host-plant resistance through characterization of the early infection processes of Meloidogyne incognita race 3 in susceptible (Lahontan) and resistant (Moapa) alfalfa cultivars by light microscopy and transmission electron microscopy. Neither differential penetration of M. incognita J2 into Lahontan, nor migration of J2 from Moapa, played a significant role in the resistance mechanism(s). Coiled nematodes in the cortex were observed in greater numbers in the Moapa 48 hours after inoculation. This position was interpreted as a sign of disorientation and starvation. By 96 hours after inoculation, no coiled nematodes were observed in Lahontan. In Moapa, resistance probably depends not only on the failure of the J2 to identify a suitable feeding site and initiate giant cells, but also on its inability to maintain the giant cells, once they are initiated. At the ultrastructural level, 48 hours after inoculation, the most evident change in both cultivars was the appearance of a uniform interstitial material (IM) between the nematode cuticle and the root cell wall. At 96 hours, IM in Moapa was completely agglutinated while in Lahontan it was still uniform or only slightly agglutinated. Due to these clear differences between both cultivars I propose that the IM plays a role in the resistance of Moapa to M. incognita. Immunolabeling techniques were employed to determine if the distribution of the nematode's surface coat, deposited in host tissues, differs in resistant and susceptible alfalfa cultivars. At 72 hours after inoculation, labeling of surface coat epitopes in Moapa was stronger than at 24 and 48 hours after inoculation. Labeling was observed on the nematode's cuticle, the plant cell wall, and the IM. In Lahontan, 72 and 96 hours after penetration, labeling of the surface coat epitopes was observed on the nematode's cuticle, the root cell walls, and the cell wall junctions of cells near the nematode, but not in direct contact with the cell.en_US
dc.typetexten_US
dc.typeElectronic Dissertationen_US
dc.subjectMeloidogyne incognitaen_US
dc.subjectRoot-knot nematodeen_US
dc.subjectalfalfa resistanceen_US
dc.subjectUltrastructural responsesen_US
dc.subjectMeloidogyne incognita surface coaten_US
dc.subjectMISC nematode antibodyen_US
thesis.degree.namePhDen_US
thesis.degree.leveldoctoralen_US
thesis.degree.disciplinePlant Pathologyen_US
thesis.degree.disciplineGraduate Collegeen_US
thesis.degree.grantorUniversity of Arizonaen_US
dc.contributor.advisorMcClure, Michael A.en_US
dc.contributor.chairMcClure, Michael A.en_US
dc.contributor.committeememberStock, S. Patriciaen_US
dc.contributor.committeememberOlsen, Maryen_US
dc.contributor.committeememberKubota, Chierien_US
dc.contributor.committeememberMcCloskey, Williamen_US
dc.identifier.proquest1324en_US
dc.identifier.oclc137355024en_US
All Items in UA Campus Repository are protected by copyright, with all rights reserved, unless otherwise indicated.