Registration of LONREN-1 and LONREN-2 Germplasm Lines of Upland Cotton Resistant to Reniform Nematode

Cotton (Gossypium hirsutum L.) germplasm lines LONREN-1 (Reg. No. GP-977, PI 669509) and LONREN-2 (Reg. No. GP-978, PI 669510) were developed and released by the USDA-ARS, Texas Agricultural Experiment Station and Cotton Incorporated in 2007 to provide breeders with desirable germplasm resistant to the reniform nematode (Rotylenchulus reniformis Linford and Oliveira). The resistance was transferred from wild G. longicalyx via a triple-species hybrid. Crosses, backcrosses, and single plant selections were used to develop the F-2 progeny used for seed production. Resistance was followed with the codominant simple sequence repeat BNL 3279_114 marker, located 1.4 cM proximal and the phenotypic marker 'greenfuzz' (LTCOL_F) located 4.5 cM distal to the Ren(lon) resistance gene on chromosome 11. A single nucleotide polymorphism marker also was developed for rapid screening of large numbers of seed. The introgressed chromosome segment is smaller in LONREN-2 than in LONREN-1. Both lines reduced reniform populations by 95% in growth chamber bioassays and by 50 to 90% in fields. In the absence of nematodes in the field, growth rate, yield, and fiber quality of the lines were similar to that of the 'Fibermax 958' parent. In the presence of reniform nematodes in the field, the lines often showed stunting and yield losses, probably due to enhanced severity of fungal seedling diseases, especially Thielaviopsis root rot. The seedling diseases in LONRENs were diminished by control measures such as fungicides, nematicides, and crop rotation with corn or sorghum, and were negligible in a second year of planting in the same field.