Genetics of Reniform Nematode Resistance in Gossypium arboreum Germplasm Line PI 529728

Abstract

Reniform nematode (Rotylenchulus reniformis) is a serious pathogen of cotton in the United States and management has been difficult due to the lack of resistant upland cotton (Gossypium hirsutum) varieties. The diploid G. arboreum germplasm line PI 529728 was identified as a potential new source of R. reniformis resistance. Line PI 529728 was crossed with the highly susceptible G. arboreum germplasm line PI 529729 to develop F1, BC1F1, and F2 populations that were screened for nematode resistance under controlled environmental conditions to determine the genetics of resistance. The 10 F1, 69 BC1F1, and 332 F2 plants were inoculated with 1,000 vermiform nematodes and the number of swollen females on the root systems was determined 28 days after inoculation. The F1 plants supported more nematodes than the susceptible control genotype PI 529251 (G. hirsutum accession Deltapine 16) indicating resistance was a recessive trait. For the BC1F1 and F2 populations, plants supporting the same or a reduced level of infection that developed on the resistant control genotype PI 163068 (G. barbadense accession Texas 110) were rated as resistant. Based on this classification of resistance and susceptibility, it was predicted that a single recessive gene was conferring resistance; although, the BC1F1 population had more susceptible plants than expected. Additionally, highly resistant plants were observed in the BC1F1 and F2 populations. This information will aid in the introgression of R. reniformis resistance from PI 529728 into upland cotton for the development of resistant varieties.