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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

2010 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

This is a new project that replaced 6202-22000-026-11S and is continuing and expanding the work of the precursor project. Stunting observed in 2009 field plots of cotton plants resistant to the reniform nematode was confirmed in field plots in 2010. The primary cause of this stunting has been identified as enhanced susceptibility to soil borne pathogenic fungi. This information and that to be provided by ongoing project work will greatly advance our understanding of the stunting phenomenon and its link to reniform nematode resistance, and will allow exploitation of the G. longicalyx resistance in developing new nematode-resistant commercial cottons for productive and profitable use by U.S. farmers. The ADODR of this project and the cooperator are located in close physical proximity, and are in contact with one another on an ongoing basis. The ADODR and the cooperator (or key personnel working under the cooperator) meet and discuss the direction and progress of the project on a regular basis.


Last Modified: 8/21/2014
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