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Anne M. Gillen and Fredrick A. Bliss

Peach rootstock breeding may be accelerated by utilization of molecular markers linked to the root-knot nematode resistance locus (Mi) to screen segregating populations. A genetic linkage map was constructed using RFLP markers in an F2 population (PMP2) that is segregating for this locus. PMP2 is derived from a controlled cross of the relatively diverse peach rootstocks Harrow Blood (susceptible) and Okinawa (homozygous resistant). Bulked Segregant Analysis was applied using RAPD markers. A single small (227 base pairs) RAPD marker was found to be linked to the dominant resistant allele of Mi at a distance of 10 cM. This new marker joined the Mi locus to the RFLP linkage map and showed that two dominant RFLP markers are located between the RAPD marker and Mi. RFLPS are expensive, time-consuming and RAPD markers are unreliable, and therefore both are unsuitable for screening breeding populations. We attempted to convert the RAPD marker to a more breeder-friendly CAPS marker. The converted CAP marker was dominant. Attempts to convert the CAP marker to a co-dominant marker were not successful. The utility of the CAP marker was tested in an open pollinated F2 population derived from the F1 parent of PMP2 and in several rootstocks. The genetic linkage map was compared to other Prunus maps. The PMP2 linkage group containing the Mi locus can be related to the peach × almond linkage group which contains the phosphoglucomutase Pgm-1 locus.

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Sindynara Ferreira, Luiz Antonio A. Gomes, Wilson Roberto Maluf, Vicente Paulo Campos, José Luiz S. de Carvalho Filho, and Daniela Costa Santos

beans are considered good hosts for both Meloidogyne incognita and M. javanica with losses that can reduce pod numbers and seed weight per plant by 65%. Several studies report the occurrence of these root-knot nematodes in P. vulgaris L. cultivars

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W. Alan Erb and Randall C. Rowe

Abbreviations: Fol 1 and 2, Fusarium oxysporum f. sp. lycopersici races 1 and 2; Forl, Fusarium oxysporum f. sp. radicis-lycopersici; Mel, Meloidogyne incognita; TMV, tobacco mosaic virus; Verd, Verticillium dahliae. 1 Assistant Professor

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Judy A. Thies, Don W. Dickson, and Richard L. Fery

The southern root-knot nematode, Meloidogyne incognita (Chitwood) Kofoid and White, causes severe yield losses to pepper production in sub-tropical climates throughout the world ( DiVito et al., 1985 , 1992 ; Sasser and Freckman, 1987 ). In

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Judy A. Thies and Amnon Levi

. citroides PIs that showed moderate resistance to M. arenaria race 1 for resistances to M. incognita race 3 and M. arenaria race 2. Materials and Methods Inocula. Meloidogyne incognita race 3 and M. arenaria race 2 were cultured on

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Andrew P. Nyczepir, Alexis K. Nagel, and Guido Schnabel

reproduction, respectively, of the root-knot nematode, Meloidogyne incognita (Kofoid & White, 1919) Chitwood, 1949 ( Cox et al., 2006 ; Nagel et al., 2008 ). Additionally, these transgenic tobacco and plum lines had increased tolerance to Phytophthora

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Hetal M. Kalariya, Guido Schnabel, Cesar Petri, and Ralph Scorza

root; P = 0.3377 at α = 0.05 for galls/g of root; Fig. 5 ). Fig. 5. Reproduction of Meloidogyne incognita on roots of ‘Stanley’ control line, ‘Bluebyrd’ control line (BB-OP-0), transgenic lines 4J, and BB-OP-1. ( A ) Number of eggs per gram of root

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Alexis K. Nagel, Hetal Kalariya, and Guido Schnabel

reduced symptom severity when challenged with the stramenopile pathogen Phytophthora cinnamomi and both lines trended toward increased tolerance to the root-knot nematode Meloidogyne incognita ( Nagel et al., 2008 ). The presence of foreign gene

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Ke Cao, Lirong Wang, Gengrui Zhu, Weichao Fang, Chenwen Chen, and Pei Zhao

environments, and pest resistance ( Desmond and Daniele, 2008 ). Three major RKN species, Meloidogyne incognita (MI), M. javanica (MJ), and M. arenaria (MA), are present in most areas with tropical and Mediterranean climates ( Lamberti, 1979 ; Sasser

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H.Y. Hanna

A study was conducted in Summer 1996 and 1997 to determine the residual effects of planting nematode-resistant vs. susceptible tomato (Lycopersicon esculentum Mill.) cultivars and use of white vs. black polyethylene mulch on the growth and yield of a subsequent muskmelon (Cucumis melo L.) crop. Tomato cultivars were planted in early April and harvested in June and early July. Muskmelons were planted in late July on the same beds. Muskmelons, planted after the nematode-resistant tomato cultivar Celebrity, produced significantly greater marketable yield and more fruit per hectare in both years than did muskmelons planted after the nematode-susceptible tomato cultivar Heatwave. Plant dry weight of muskmelons was greater and the percentage of their galled roots was smaller when planted after nematode-resistant tomatoes than when planted after nematode-susceptible ones. Mulching tomatoes with black or white polyethylene had no significant effect on growth, yield, and root galling of subsequent muskmelon crops.