Are Renari From Gossypium aridum and Renlon From G. longicalyx Duplicate Genes?

Reniform nematode (Rotylenchulus reniformis) has become a major pest of cotton in the mid-south area of the United States. Resistance genes, Ren^ari and Ren^lon from Gossypium aridum and G. longicalyx, respectively, have been identified and introgressed into Upland cotton. Using plant materials containing either Ren^ari  or  Ren^lon gene as parents, we developed an F₂ population of 184 progeny for genetic evaluation of nematode resistance. The response of F₂ plants to nematode inoculation was evaluated in a growth chamber. Microsatellite markers BNL2662 and BNL3279 were analyzed to assist selection of proper parents and F₁ plants, and to study the segregation of the resistance genes among the F₂ progeny.  Our results suggested that Ren^ari and Ren^lon were duplicate genes with Ren^ari residing on chromosome 21, and Ren^lon on chromosome 11. F₂ plants containing either Ren^ari  or Ren^lon had significantly fewer nematodes than the susceptible Upland cotton genotype.  No significant difference in nematode resistance was found between plants containing Ren^ari and those having Ren^lon, indicating that these two genes may have similar resistance mechanisms. Pyramiding Ren^ari and Ren^lon further enhanced plant resistance to reniform nematodes.