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United States Department of Agriculture

Agricultural Research Service

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Research Project: Reniform Nematode Resistance

Location: Insect Control and Cotton Disease Research Unit

Project Number: 3091-22000-031-12
Project Type: Specific Cooperative Agreement

Start Date: Dec 15, 2009
End Date: Dec 14, 2014

Objective:
The ultimate goal is to provide U.S. cotton growers with an economical solution to reniform nematodes, Rotylenchulus reniformis, which have been reducing yields over $100M per year. Through complex manipulations, we jointly created non-GMO lines extremely resistant to the nematode (e.g. LONREN-1 and LONREN-2) using a naturally occurring gene from a non-cultivated African species, Gossypium longicalyx. However, all such resistant lines are agronomically debilitated in many fields – the plants are smaller and less productive. Such effects were not unexpected, and are most likely due to alien genes linked to the nematode resistance. These probably cause susceptibility to domestic pathogens and/or commonly used herbicides. Objectives of the joint Texas A&M University and USDA, ARS research are: 1) Break the linkages between the genes for reniform nematode resistance and the flanking genes that affect agronomic performance and fiber traits (Texas A&M University); 2) Develop a rapid, accurate bioassay to measure seedling stunting associated with the chromosome segment introgressed from G. longicalyx, and use the bioassay to identify desirable recombinants (USDA); and 3) Confirm resistance of recombinants to nematodes and stunting in the field (USDA).

Approach:
To break the linkages between the genes for reniform nematode resistance and the flanking genes that affect agronomic performance and fiber traits, we will synthesize heterozygotes that contain nearby recombination events, create testcrosses, and screen progeny with linked molecular markers to find recombinants, then jointly test the desired recombinants experimentally to determine their resistance and agronomic phenotypes. Concommitant with this process will be the identification of markers progressively closer to the resistance gene. Develop a rapid, accurate bioassay to measure seedling stunting associated with the chromosome segment introgressed from G. longicalyx, and use the bioassay to identify desirable recombinants (USDA). Confirm resistance of recombinants to nematodes and stunting in the field (USDA).

Last Modified: 10/23/2014
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