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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

2011 Annual Report


1a.Objectives (from AD-416)
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).


1b.Approach (from AD-416)
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).


3.Progress Report

The goal of this project is to develop new cotton germplasm that will be highly resistant, if not immune, to the reniform nematode, a very highly destructive pathogen of cotton in many areas of the U.S. Project work in FY 2011 included collection of RNA samples from eleven progeny developed from previous cross-breeding work. From these samples, libraries of genetic information were prepared. In addition, crosses were made in the field between 19 plants resistant to the reniform nematode and a commercial cultivar. Progeny are being tested for reniform resistance and stunting. A detailed pedigree of all populations was tabulated. As the work progresses, new information will be developed that will advance our understanding of the relationship between resistance to the reniform nematode and plant stunting. The work will provide foundational information to support efforts aimed at developing new reniform nematode-resistant cotton cultivars that do not show stunting in the field and that will be appropriate for productive use by U.S. farmers. The ADODR of this project and the cooperator are located in close physical proximity, and are in contact with each other on a weekly basis for discussions on the direction and progress of the work.


Last Modified: 8/29/2014
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