Construction Of A SSH Library Of Resistant Cultiver Jimian20 Induced By Verticillium Dahilae

Verticillium wilt is a worldwide serious disease in cotton. It restricts the development of cotton yield. In china, the production of cotton play an important role in economy, but the yield is restricted by Fusarium and Verticillium wilts, especially Verticillium wilts. So how to prevent and control Verticillium wilt is a problem to be solved. Using resistant cultivars is an effective and economical method for controlling Verticillium wilt. To breed resistant cultivars, first we must know the mechanism of the disease and search resistance genes. Development of molecular biological technique provides a powerful tool for studying disease resistant genes and a new gene source for molecular breeding of Verticillium wilt resistant cultivars.In this paper, to study the expression of disease resistance genes of upland cotton induced by Verticillium dahliae, a cDNA library was constructed by suppression subtractive hybridization (SSH) based on the material induced by Verticillium dahliae after 8h, 12h, 24h and 48h as a tester, the material of control as a driver. Eight hundred clons were stored and piasmid DNAs were extrated randomly to examine insert size. The results showed that the average insert size is about four hundred base pairs. Twenty clons which were selected randomly were subsequent to be sequenced. ESTs similarity analysis via BLASTx and BLASTn software showed that the twenty ESTs all have homology to sequences with known functions. With the result of BLASTn, twelve ESTs have homology to sequences with known function, the ratio is 60%. With the result of BLASTx fourteen ESTs have homology to sequences with known function, the ratio is 70%. Querying the dbEST of GenBank, the results revealed that most of these ESTs have high homology with the cDNAs induced by abiotic or biotic stresses in plants.Based on the result of BLASTx, BLASTn and Beavn's (1998) classify standard, the ESTs were classified according to their function. The genes obtained from Jimian20 induced by Verticillium dahliae, relate to several kind of disease resistance related genes and signal tranduction. For example, sample 3 and A21 have homology with serine/threonine kinase, sample 4 has homology with glutathione s-transferase, sample 16 has homology with ACC oxidase, and sample 10 has homology with disease resistance-reponsive family protein. These homology genes involved in R gene related signal transduction, SA related signal transduction and so on.According to our research, a lot of genes (signal transduction, intracellular traffic, transcription, cell structure function) have the analogous mechanism in the resistance process when plant faces all kinds of environmental stresses. At last, basing on the disease resistance genes screened out from our research, we discuss the possible moleculer mechanism of cotton Verticillium wilt resistance.