cDNA library of the Upland cotton resistant cultivar, Jimian 20, was constructed using suppression subtractive hybridization （SSH） and pGEM-T Easy vector under the stress of Verticilliurn dahliae at 8h, 12h, 24h and 48h post inoculation. This SSH library included eight hundred positive clones. The insert sizes ranged from 0.2kb to lkb, averaged 400bp, based on restriction endoenzyme digestion and nested PCR. Twenty random clones were selected and sequenced. ESTs similarity analysis via BLASTn and BLASTx showed that all of the twenty ESTs were homologous to the sequences with known functions. Twelve were as known sequences in the BLASTn, accounted for 60% of the total ESTs tested. Fourteen, i. e, 70% of the total, were as known sequences in the BLASTx. According to the classification criteria of plant gene function, these homologous sequences were related to ten kinds of disease resistance genes as those reported, including serine/threonine kinase, glutathi- one S-transferase, alcohol dehydrogenase, cytochrome P450, ACC oxidase, etc. Querying the Gen-Bank dbEST, as much as 75% of these ESTs were of high homology with the cDNAs that were found under the abiotic or biotic stresses in plants. These stress involved pathogen, low temperature, ultraviolet, heat shocking, salt stress, oxygen stress, and salicylic acid etc.
disease resistance gene