Plants have evolved sophisticated molecular defense mechanisms in order to survive disease conditions. So far, a number of pathogen resistance (R) genes have been reported in plants. These R genes are thought to be involved in activating the signals that lead to disease resistance. The structural specificity of R genes products makes it possible to isolate these genes from plants by homology based techniques. Knowledge regarding molecular organization of R genes in cotton is limited and other resistant gene analogues (RGAs) still need to be identified for Cotton Leaf Curl Disease (CLCuD) resistance, particularly from Gossypium arboreum. This study has, therefore, been designed to identify the natural resistance related genes from Gossypium arboreum against CLCuV. In addition to G.arboreum (resistant to CLCuV), G. hirsutum L. var S12 (highly susceptible to CLCuV), G. hirsutum L.var. CP15/2 and LRA (partially resistant to CLCuV) were used as reference controls to facilitate identification of defense related genes. This paper describes several differentially expressed transcripts through DDRT-PCR on total RNA from G. arboreum and some other tetraploid cotton species. The nucleotide sequence of these genes, when compared to the reported database, indicated that some of the differentially expressed transcripts had homology to the reported R-genes.Key words: Pathogen resistance genes (R-genes), G. arboreum, differential display, cotton leaf curl virus (CLCuV), RT-PCR
