Reproduction of a root-knot nematode population on flue-cured tobacco homozygous for Rk1 and/or Rk2 resistance genes and the effect of soil temperature on resistance gene efficacy

dc.contributor.authorPollok, Jillen
dc.contributor.committeechairJohnson, Charles S.en
dc.contributor.committeememberEisenback, Jonathan D.en
dc.contributor.committeememberReed, T. Daviden
dc.contributor.departmentPlant Pathology, Physiology, and Weed Scienceen
dc.date.accessioned2015-09-18T20:08:57Zen
dc.date.available2015-09-18T20:08:57Zen
dc.date.issued2015-09-01en
dc.description.abstractUtilizing resistant cultivars is a main control strategy for root-knot nematodes in flue-cured tobacco (Nicotiana tabacum L.). Most commercial cultivars possess the Rk1 gene, providing resistance to races 1 and 3 of Meloidogyne incognita and race 1 of M. arenaria. This initiated a shift in root-knot populations to other species and races, creating a need for resistance to those populations. Numerous cultivars possess a second resistance gene, Rk2. Greenhouse experiments investigated whether possessing both Rk1 and Rk2 increases resistance to a variant of M. incognita race 3 compared to either gene alone, and if high soil temperatures impact their efficacy. Root galling, numbers of egg masses and eggs, and the reproductive index were compared from roots of Coker 371-Gold (susceptible), NC 95 and SC 72 (Rk1Rk1), T-15-1-1 (Rk2Rk2), and STNCB-2-28 and NOD 8 (Rk1Rk1 and Rk2Rk2). The same data were analyzed from plants in open-top root zone cabinet growth chambers set to 25ºC, 30ºC, and 35ºC to examine if resistance is temperature sensitive. Despite variability, Rk1Rk2 entries conferred greater resistance than entries with Rk1 or Rk2 alone. Entries with Rk1 alone reduced galling and reproduction compared to the susceptible control, whereas T-15-1-1 (Rk2) did not, but often suppressed reproduction. An apparent reduction in nematode reproduction was observed at 25ºC and 30ºC on entries possessing Rk1 and Rk1Rk2 compared to the control and Rk2. However, no apparent differences in reproduction occurred on Rk1 and/or Rk2 entries at 35ºC compared to the control, indicating parasitism increased on resistant entries at higher temperatures.en
dc.description.degreeMaster of Science in Life Sciencesen
dc.format.mediumETDen
dc.identifier.othervt_gsexam:6133en
dc.identifier.urihttp://hdl.handle.net/10919/56597en
dc.publisherVirginia Techen
dc.rightsIn Copyrighten
dc.rights.urihttp://rightsstatements.org/vocab/InC/1.0/en
dc.subjectMeloidogyneen
dc.subjectMeloidogyne incognitaen
dc.subjectMeloidogyne arenariaen
dc.subjectNicotiana tabacumen
dc.subjectflue-cured tobaccoen
dc.subjectreproductive indexen
dc.subjectVirginiaen
dc.titleReproduction of a root-knot nematode population on flue-cured tobacco homozygous for Rk1 and/or Rk2 resistance genes and the effect of soil temperature on resistance gene efficacyen
dc.typeThesisen
thesis.degree.disciplinePlant Pathology, Physiology, and Weed Scienceen
thesis.degree.grantorVirginia Polytechnic Institute and State Universityen
thesis.degree.levelmastersen
thesis.degree.nameMaster of Science in Life Sciencesen

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