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How different or similar are nematode communities - International ...
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TOPIC NINE – POSTER PRESENTATIONS<br />
Effect of Meloidogyne incognita Resistance Genes in Cotton on the<br />
Reproduction of M. mayaguensis<br />
Brito, J.A. (1), R. Kaur (2), R.F. Davis (3) & D.W. Dickson (2)<br />
(1) Nematologist, Division of Plant Industry, Florida Department of Agriculture and Consumer Services, P. O.<br />
Box 147100, Gainesville, FL 32614-7100; (2) Post-Doctoral Associate and Professor, Entomology and<br />
Nematology Department, University of Florida, Gainesville, FL 32611-0620; (3) Research Plant Pathologist,<br />
USDA-ARS, Crop Protection and Management Research Unit, P. O. Box 748, Tifton, GA 31793.<br />
Meloidogyne mayaguensis was first reported in the continental United States in 2002, and<br />
some isolates can reproduce on cotton. Meloidogyne incognita is the single most important<br />
pathogen of cotton in the United States, and efforts to incorporate resistance to M. incognita<br />
into cotton cultivars are ongoing. Our objective was to determine whether resistance to M.<br />
incognita in cotton will also confer resistance to M. mayaguensis. Two greenhouse<br />
experiments showed that gall and egg mass indices, eggs per gram of root, and reproductive<br />
factor (Rf) differed significantly among cotton genotypes resistant or susceptible to M.<br />
incognita when inoculated with M. incognita, but not when inoculated with M. mayaguensis.<br />
Results indicated that resistance to M. incognita in cotton does not confer resistance to M.<br />
mayaguensis; however, on cotton susceptible to M. incognita, inoculation with M.<br />
mayaguensis resulted in gall and egg mass indices, eggs per gram of root, and Rf less than on<br />
plants inoculated with the same number of M. incognita. On cotton resistant to M. incognita,<br />
the two nematode species reproduced similarly.<br />
Variability in Infection and Reproduction of Meloidogyne javanica on<br />
Tomato Rootstocks with the Mi Resistance Gene<br />
Cortada, L. (1), F.J. Sorribas (2), C. Ornat (2), I. Kaloshian (3) & S. Verdejo-Lucas (1)<br />
(1) IRTA. Crta. de Cabrils Km 2. 08348 Cabrils, Barcelona, Spain.; (2) Departament d’Enginyeria<br />
Agroalimentària i Biotecnologia. Universitat Politècnica de Catalunya. Campus Baix Llobregat, Edifici ESAB,<br />
Av. Canal Olímpic 15. 08860 Barcelona, Spain; (3) Department of Nematology, University of California.<br />
Riverside, California, 92521, USA<br />
Grafting became widely used in the late 1990s with the appearance of a disease known as<br />
‘vascular collapse’. Most tomato rootstocks are interspecific hybrids of Solanum<br />
lycopersicum × S. habrochiates or Solanum lycopersicum × Solanum spp. The response of 10<br />
tomato rootstocks with the Mi resistance gene to an initial inoculum of a Mi avirulent<br />
population of Meloidogyne javanica was determined in pot tests conducted in spring and<br />
summer. In a field test, the rootstocks were subjected to continuous exposure to high<br />
population densities of the nematode. The presence of the Mi resistance gene in the<br />
rootstocks was determined using the PCR- based co-dominant markers REX-1, developed to<br />
detect the introgressed Mi region in hybrids of S. lycopersicum × S. peruvianum, and the<br />
Mi23, designed for Solanum hybrids. Nematode infectivity (egg masses), and reproduction<br />
(eggs g -1 root) was highly variable in the spring tests. Rootstocks cvs. PG76, Gladiator, and<br />
MKT-410 consistently responded as highly resistant (Pf/Pi < 1 and reproduction index [RI] <<br />
10%), and were as efficient as the resistant tomato cultivars. The relative resistance levels of<br />
rootstocks cvs. Brigeor, 42851, 43965, Big Power and Heman varied depending on the<br />
susceptible cultivar used for reference or the duration of the test. Rootstocks cvs. PG76 and<br />
5 th International Congress of Nematology, 2008 234