| Plants in their natural environments are constantly challenged by a wide spectrum of pathogens including viruses, bacteria, fungi, nematodes, etc. Cotton, a major source of cotton fiber for the textile industry, is an important economic crop. A variety of pathogens can infect cotton. In China, cotton blight and cotton verticillium wilt (causative pathogen Verticillium dahliae) are especially severe and cause serious damage to cotton production annually. It is well documented that planting disease resistant cultivars is the most effective approach to the control disease. Gossypium hirsutum is the major cotton species planted in China and breeding of blight-resistant cultivars has been very fruitful. However, breeding of cultivars resistant to V. dahliae has proven to be unsuccessful, largely due to the lack of germplasm known to be immune or highly resistant to the fungal pathogen V. dahliae. The successful cloning of RGAs and DGAs in various crops prompted us to clone RGAs and DGAs sequences from cotton. It is hoped that isolation and characterization of RGAs and DGAs in cotton should help identify DNA markers closely linked to the R genes in cotton, and ultimately lead to the mapping and cloning of cotton R genes. It is expected that the isolation and identification of R genes against cotton verticillium wilt should facilitate breeding and development of cotton cultivars which are highly resistant to this devastating pathogen.Gossypium barbadense L. cv. Hai7124, a widely used verticillium wilt-resistantcultivar in China for genetic study and breeding, was employed for cloning RGAs and DGAs. 79 NBS sequences, 21 STK sequences and 11 DGAs were cloned from disease-resistance cotton. Previously 143 NBS-encoding RGAs were cloned from cotton by a PCR-based strategy. Among 79 NBS sequences from this study 13 belonged to the new sequences relative to NBS-encoding RGAs cloned in cotton, the... |
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