Location: Plant Stress and Germplasm Development Research
Project Number: 3096-21000-022-017-N
Project Type: Non-Funded Cooperative Agreement
Start Date: Sep 15, 2018
End Date: Sep 30, 2022
Objective:
1. Evaluate root cell wall composition on cotton progeny or germplasm with known resistance/susceptibility response to pathogen infection such as FOV races 1 and 4 (FOV1 and FOV4), and RKN.
2. Identify genes, compounds or proteins involved in repair and cell wall reinforcement-fortification.
3. Develop a screening assay-tool for identifying and selecting resistant breeding lines to FOV and RKN.
Approach:
Multiple evidences from model and crop species demonstrated that the cell wall acts as a physical barrier against pathogen infection. Hence it is possible to enhance cotton resistance against Fusarium oxysporum f. sp. vasinfectum (FOV) by identifying cotton entries with stronger cell walls which acts as a strong physical barrier against pathogen entry-infection. The goal of this proposed project is to explore if cotton (Gossypium spp.) root cell wall composition can be used as an indicator for resistance-enhancement against FOV races 1 and 4 (FOV1 and FOV4) and the pest root-knot nematode (RKN) Meloidogyne incognita. FOV is a worldwide distributed soil borne vascular pathogenic fungus that penetrates plant tissues causing damage, cell necrosis, and wilting symptoms in plants. This fungus has been a continuing problem causing cotton economic losses in the U.S. and worldwide. We will isolate cell walls from entries with known disease response to FOV1, FOV4, and RKN to analyze their composition. Two-step approach will be used to screen the lines. We first perform a rapid screening using histochemical analysis of the cotton root cross sections by staining for various cell wall polymers. This is a rapid technique to identify the lines with enhanced cell wall polymers. Then the lines with higher cell wall polymers will be further analyzed for the biochemical composition by wet laboratory methods (HPLC/GC/Spectrophotometer). Several cell wall fortifications such as deposition of callose, cellulose, lignin, phenolic compounds and structural proteins have been reported to occur directly below the point of attempted penetration to prevent the pathogen infection. Callose (ß, 1-3 glucose polymer) is a cell wall component that is quickly deposited in response to the pathogen infection. Breeding material or cotton entries have been selected/developed with resistance to FOV such as race 4 (FOV4) and RKN by the USDA-ARS and University cooperators. These and additional entries of interest identified from ongoing screening and selection efforts at the USDA-ARS, CSRL, Plant Stress and Germplasm Development Research, Lubbock, TX and/or other germplasm sources will be used as appropriate for this project. In addition, using the next generation sequencing technology, information from expressed genes have been generated from infected and uninfected roots of susceptible and resistant/tolerant entries, including resistant/tolerant PS6 and susceptible PS7 to FOV4. From this USDA-ARS ongoing RNA-Seq transcriptomic research, candidate genes involved in cell wall fortification will be identified. SNP-biomarkers will eventually be used in marker-assisted breeding for developing tolerant cotton lines. Resistance to FOV4 was originally identified in commercial Pima cotton (G. barbadense L.), Commercial Phytogen 800, and originated-pool germplasm, Pima S-6. However, so far, resistance in Upland cotton (G. hirsutum L.) has not been identified and commercial Upland varieties are not available. Therefore, there is still a critical need to identify and develop upland cotton germplasm and cultivars with disease resistance, especially to FOV4.
