ARS | Publication request: SSR MARKER(S) ASSOCIATED WITH ROOT-KNOT NEMATODE RESISTANCE GENE(S) IN COTTON

Submitted to: Journal of Cotton Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: October 1, 2003
Publication Date: December 1, 2003
Citation: Bezawada, C., Saha, S., Jenkins, J.N., Creech, R.C., McCarty, J.C. 2003. SSR marker(s) associated with root-knot nematode resistance gene(s) in cotton. Journal of Cotton Science. 7:179-184.

Interpretive Summary: Root-knot nematode (RKN) cause a major yield loss in US cotton, Gossypium hirsutum. The primary limitation for developing resistant germplasm to RKN is the limited information available about resistant gene(s). Molecular markers linked to RKN-resistant gene(s) provide the option to select on the genotype rather than on the phenotype. The objectives of this research were to: (1) identify DNA markers associated with the resistance of RKN in Upland cotton and (2) determine the mode of inheritance of RKN resistance gene(s). Moderately resistant parent, Clevewilt, and susceptible parent, Stoneville 213, and their F2 population were genotyped using 120 SSR primer pairs, providing 28 polymorphic markers. Results showed that root gall indices were the best indicator for measuring resistance. Gall indices for this population segregated in the Mendelian ratio 3:1, suggesting the resistant parent had a recessive gene for resistance to galling. The BNL 1421 SSR marker explained 8% of the gall index variation in the segregating F2 populations. DNA markers associated with such small resistance effects will be useful in pyramiding genes for resistance using a molecular breeding approach.

Technical Abstract: Nematodes cause significant yield loss in US cotton, Gossypium hirsutum. Very few cotton lines are resistant to root-knot nematode [RKN] (Meloidogyne incognita spp.), one of the major nematode pest species in the US Cotton Belt. DNA markers for root-knot nematode resistance gene(s) will provide tools in breeding resistant cultivars. The objectives of this research were to: (1) identify DNA markers associated with the resistance of RKN in Upland cotton and (2) determine the mode of inheritance of RKN resistance gene(s). Modertately resistant parent, Clevewilt, and Stoneville 213, susceptible parent, and their F2 population were genotyped using 120 SSR primer pairs, providing 28 polymorphic markers. Results showed that the gall indices were the best indicator for measuring resistance. Gall indices for this population segregated in the Mendelian ratio 3:1 suggesting the resistant parent had a recessive gene for resistance to galling. The BNL 1421 marker explained 8% of the gall index variation in the segregating F2 population. DNA markers associated with such small resistance effects will be useful in pyramiding genes for resistance using a molecular breeding approach.