Location: Crop Genetics ResearchTitle: Genetic characterization of reniform nematode resistance for Gossypium arboreum accession PI 417895 Author
Submitted to: Plant Breeding
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/11/2017
Publication Date: 2/12/2018
Citation: Erpelding, J.E., Stetina, S.R. 2018. Genetic characterization of reniform nematode resistance for Gossypium arboreum accession PI 417895. Plant Breeding. 137:81-88. https://doi.org/10.1111/pbr.12560.
Interpretive Summary: Reniform nematode is a microscopic worm that lives in the soil and feeds on the roots of upland cotton plants resulting in lower cotton fiber yields. The best method of controlling this nematode is through the use of resistant cotton varieties; however, no resistant upland cotton varieties are available. Sources of resistance have been identified in the Asiatic cotton germplasm collection. These Asiatic cotton varieties have been collected from many different countries and could be a source of genetic diversity for reniform nematode resistance. One obstacle to using these varieties as a source of resistance genes is that they have half the number of chromosomes as upland cotton, which requires specialized breeding procedures in order to transfer resistance between the two species. Therefore, determining the number of genes controlling resistance to reniform nematode is important in order to successfully transfer resistance to upland cotton. A population of 300 plants was developed by crossing a highly resistant Asiatic cotton variety (PI 417895) with a susceptible Asiatic cotton variety (PI 529729). The 300 plants were infected with reniform nematodes and the roots were evaluated to determine which plants showed resistance. By evaluating these data, it was determined that two genes were controlling resistance. Transferring multiple resistance genes to upland cotton can be difficult and further research is ongoing to develop DNA markers associated with these resistance genes that can be used to select plants with both genes.
Technical Abstract: Reniform nematode (Rotylenchulus reniformis) is an important root pathogen of cotton in the southeastern United States and management is hindered by the lack of host-plant resistance in upland cotton (Gossypium hirsutum). The G. arboreum germplasm collection is an important source of resistance. Transferring resistance to G. hirsutum requires specialized breeding approaches; therefore, characterizing the genetic inheritance of resistance could improve the efficiency of introgression. The G. arboreum accession PI 417895 is highly resistant to R. reniformis and a segregating population of 300 F2 plants was developed for phenotypic characterization of R. reniformis resistance. The population showed quantitative variation for nematode infection. Forty-nine plants were classified as resistant, indicating resistance is a recessive trait, but the data did not support the one or two recessive gene models. If the 139 F2 plants classified as resistant or moderately resistant were instead classified as resistant, the data would support a two recessive gene model based on a 7:9 segregation ratio. Considering this second approach, accession PI 417895 represents a new source of R. reniformis resistance with two major genes conferring resistance. These results further suggest expression of susceptibility would require complementary gene action. Introgression of multiple resistance genes will require the development of larger populations in order to recover the resistant phenotype in G. hirsutum; although, a marker-assisted selection approach would be desirable to increase the efficiency of recovering multiple genes.