Genetic characterization of reniform nematode resistance for Gossypium arboreum accession PI 417895

Abstract

Rotylenchulus reniformis is an important root pathogen of cotton in the south‐eastern United States, and management is hindered by the lack of host‐plant resistance in upland cotton (Gossypium hirsutum). 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 resistance. The population showed quantitative variation for nematode infection. Twenty plants showed no infection and were classified as escapes. Fifty‐four plants were classified as resistant or moderately resistant, whereas, 226 were classified as moderately susceptible or susceptible based on the nematode response of the susceptible parent, indicating resistance is a recessive trait, but these data did not support the single recessive gene model. Alternatively, this model would be supported if the 77 plants with a similar nematode response as observed for PI 417895 were classified as resistant. Twelve plants showed high levels of resistance and these data would support a two recessive gene model. Accession PI 417895 represents a new source of R. reniformis resistance with two major genes conferring resistance. Introgression of multiple resistance genes into G. hirsutum will require the development of larger populations to recover the resistant phenotype.

Genetic characterization of Gossypium arboreum accession PI 529740 for reniform nematode resistance

“…Marker-assisted selection has been used to introgress resistance from accession PI 615699, but no breeding lines with stable resistance have been developed to further characterize resistance. A single recessive gene conferred R. reniformis resistance for the moderately resistant G. arboreum accession PI 529728 (Erpelding & Stetina, 2013), which would suggest multiple resistance genes with additive effects may be required for the expression of higher levels of resistance. For the highly resistant G. arboreum accession PI 417895, two genes were reported to confer the high level of | 877 ERPELDING aND STETINa resistance with the moderately resistant phenotype conferred by a single recessive gene .…”

“…For the highly resistant G . arboreum accession PI 417895, two genes were reported to confer the high level of resistance with the moderately resistant phenotype conferred by a single recessive gene (Erpelding & Stetina, ). These results along with the results of the present study would indicate a single recessive gene conferred expression of the moderately resistant phenotype; whereas, two genes in the homozygous recessive state would be required for expression of the highly resistant phenotype.…”

“…reniformis resistance for the moderately resistant G . arboreum accession PI 529728 (Erpelding & Stetina, ), which would suggest multiple resistance genes with additive effects may be required for the expression of higher levels of resistance. For the highly resistant G .…”

“…For the R . reniformis evaluation of the F 3 generation, the shoot of each F 2 plant was vegetatively propagated as described by Erpelding and Stetina (). Seed cotton was removed from bolls at maturity, ginned and acid delinted.…”

“…The R. reniformis screening of the population followed the procedure described by Erpelding and Stetina (2018). Gossypium hirsutum accession PI 529251 (cv.…”