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United States Department of Agriculture

Agricultural Research Service

Research Project: Development of Disease and Nematode Resistance in Vegetable Crops

Location: Vegetable Research

Project Number: 6080-22000-026-00
Project Type: Appropriated

Start Date: May 01, 2012
End Date: Apr 30, 2017

Objective:
1. Determine inheritance of resistance to Phytophthora fruit rot in watermelon; and develop breeding lines with resistance to Phytophthora fruit rot and watermelon vine decline. 2. Determine genetic basis of resistance to root-knot nematodes in watermelon, identify molecular markers associated with resistance, and develop resistant breeding lines. 3. Determine genetic basis of resistance to root-knot nematodes in pepper and develop resistant breeding lines.

Approach:
Populations of watermelon segregating for resistance to Phytophthora fruit rot will be generated by crossing a highly resistant selection developed from a Citrullus lanatus var. lanatus accession with susceptible commercial cultivars of C. lanatus. These populations will be phenotyped for reaction to Phytophthora fruit rot to determine inheritance of resistance. Molecular markers closely linked to resistance genes will be identified and used in marker assisted selection (MAS) to develop fruit rot resistant breeding lines. Breadth of resistance in watermelon germplasm and breeding lines will be assessed against isolates of Phytophthora capsici from several Southeastern states. Advanced watermelon germplasm lines resistant to vine decline (caused by the whitefly-transmitted squash vein yellowing virus, SqVYV) will be developed using known sources of resistance to SqVYV in wild watermelon accessions via the pure line selection breeding procedure. The advanced resistant germplasm will be crossed with a susceptible commercial cultivar to develop segregating populations to determine inheritance of resistance to SqVYV. Genetic populations of wild watermelon (Citrullus lanatus var. citroides) segregating for resistance to southern root-knot nematode (RKN, Meloidogyne incognita) will be developed and phenotyped for reaction to RKN to determine the mode of inheritance of resistance. Molecular markers closely linked to the RKN resistance gene(s) will be identified and used for gene mapping and MAS. Watermelon populations segregating for resistance will be developed by crossing RKN-resistant C. lanatus var. citroides with cultivated watermelon, C. lanatus. These populations will be phenotyped for reaction to RKN and MAS utilized to develop RKN-resistant watermelon breeding lines. Sweet peppers (sweet banana, sweet cherry, and Cubanelle types) with resistance to southern RKN will be developed using conventional recurrent backcross breeding procedures to transfer the dominant ‘N’ gene for RKN resistance from resistant bell pepper to sweet pepper. Genetic populations of pepper (Capsicum annuum) segregating for resistance to northern RKN (M. hapla) will be developed by crossing a highly resistant selection from a C. annuum accession with a susceptible commercial C. annuum cultivar. These populations will be phenotyped for root galling and RKN reproduction to determine mode of inheritance of resistance to northern RKN.

Last Modified: 10/25/2014
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