Analysis of Lonren Reniform Nematode Resistance and "Stunting", By Marker-Assisted Dissection of an Alien R-Gene Chromosome Segment and Detection of Significant Fungal Interactions

Genetic resistance of the wild African species Gossypium longicalyx to reniform nematodes (Rotylenchulus reniformis) was previously transferred into upland cotton (Gossypium hirsutum L.). LONREN and other cotton lines containing the responsible gene, Ren^lon, are highly nematode-resistant, but when grown in nematode-infested fields, the seedlings and plants become "stunted". Hypothesized causes include hypersensitivity reaction, per se, and/or increased susceptibility to soil pathogens. To research this problem we developed Ren^lon-linked markers, mapped the Ren^lon region at high resolution, used MAS to identify recombinants between Ren^lon and nearby loci and determine if “stunting” is due to linkage drag.  In so doing, we created genomic and germplasm resources useful for genetic manipulation of chromosome-11, especially Ren^lon.  We also investigated if "stunting" is due solely to plant-nematode interactions or involves additional pathogens, including a number of replicated growth chamber experiments.