Project Summary: “Engineering resistance to cotton root rot fungus”

Cotton root rot is one of the most destructive of plant diseases, causing economic losses in numerous broadleaf crops including alfalfa (Medicago sativa), cotton, peanuts, pecans, fruit trees, grapes, and vegetable crops. It is the major reason why production of alfalfa, the world’s most important forage legume, is not economically feasible in southern Oklahoma and much of Texas. The disease is caused by the fungus Phymatotrichopsis omnivora. After more than a century of sporadic research, no effective cultural or chemical control has been developed, and no sources of genetic resistance have been identified. The regional nature of this disease, which is particularly prevalent in southern Oklahoma and north Texas, has limited its appeal to federal funding agencies. Only by utilizing multiple approaches and combining the latest tools in molecular biology and genetics with a state-of-the-art selection and breeding program will it be possible to address this devastating disease. The present proposal builds upon the scientific and intellectual infrastructure assembled in the groups of the Consortium members through Noble Foundation and National Science Foundation funded programs on the molecular genetics of the model legume Medicago truncatula. 

The overall objectives of this research are to characterize Phymatotrichopsis root rot in alfalfa at the biological, chemical and genetic levels, with the long-term goal of developing resistant alfalfa varieties. 

The objectives in the Dixon lab are to develop an engineered chemical defense strategy against cotton root rot. Clearly, the known chemical defense responses of alfalfa against other potential pathogens are ineffective against P. omnivora. If it is confirmed that there is no genetic resistance against the fungus in existing alfalfa germplasm collections, introduction of novel chemical defenses will be valuable. Based on the chemistry of the few legume species that are known to be resistant to P. omnivora, a range of plant natural products will be evaluated for antimicrobial activity against the fungus grown in culture. Most will be variants of alfalfa metabolites, facilitating their engineering into alfalfa for assessment of efficacy during natural infections.

• Dr Wensheng Li

• Dr Lloyd Sumner, Plant Biology Division, The Samuel Roberts Noble Foundation.
• Dr Kiran Mysore, Plant Biology Division, The Samuel Roberts Noble Foundation.
• Dr Carolyn Young, Forage Improvement Division, The Samuel Roberts Noble Foundation.
• Dr Joe Bouton, Forage Improvement Division, The Samuel Roberts Noble Foundation.
• Dr Bruce Roe, University of Oklahoma.
• Dr Steve Marek, Oklahoma State University.

• The State of Oklahoma