Gossypium mustelinum,a wild tetraploid cotton species endemic to the semi-arid region of northeastern Brazil,is highly resistant to verticillium wilt disease and sexually compatible with cultivated cotton(G.hirsutum or G.barbadense).In this research,capillary electrophoresis was introduced into methylation-sensitive amplification polymorphism(MSAP)analysis system,so as to analyze DNA methylation level in G.mustelinum and reveal the molecular mechanism of verticillium wilt resistance in cotton.