Studies On Molecular Marker Of Fusarium Wilt Resistance-Related Gene In Cucumber (Cucumis Sativus L.)

Cucumber fusarium wilt(Fusarium oxysporum f. sp. Cucumerinum) is a typic soil-borne disease .With the extend of planting areas ,cucumber wilt become a severe disease all over the world to affect badly output and quality of cucumber. The output reduction in cucumber gives amount to 35%～50% every year because of the occurrence of the disease. Breeding of resistant variety is a safe, economy and effective way to prenvent the pollution of the environment,pesticide remnant and to control the disease at the same time. Conventional breeding methods have been successful in variety development. Identification of resistance to wilt mainly depends on field observation . Due to the disease occurs in the whole life cycle ,there are many difficulties in field identification. Development of molecular markers,such as RFLP,RAPD,AFLP and SSR, provides a convenient, effective way to select resistant material in plant breeding and have been used in many fields .For AFLP and SSR possesses less DNA ,more sensitive ,informative, rapid and efficient ,it can be applied to more aspects than other molecular markers in breeding research . Now ,the markers of powdery mildew and downy mildew in cucumber have been found,but there was no report on molecular markers of cucumber wilt up to date. In this paper, AFLP ,SSR technology and Bulked-extremes and recessive class analysis(BERCA) were applied to study the markers linked to the resistance related gene of cucumber wilt using a F₂ population of a cross(jinchun No3.) between a highly resistant parent and a susceptible parent. The main results were as follows: 1.The field identification of F₂ progeny shows that the material resistance of cucumber is controlled by a recessive gene in the test of materials used in this paper. 2. A co-dominant AFLP marker closely linked to cucumber wilt resistant gene was discovered. By checking the polymorphism between the five resistant plants and the five susceptible plants, a co-dominant marker,E25M70-170bp/167bp,was found. Population analysis indicated that among 234 F₂ plants,47 resistant ones possessed two fragments ,which were in accordance with their resistant parent.While the 187 susceptible plants possessed one fragment which was in accordance with their susceptible parent.But there were 3 resistant plants that possessed one fragment and 16 susceptible plants that possessed two fragments.Linkage analysis indicated that the AFLP marker was linked to cucumber wilt gene,and the genetic distance was 8.12cM. 3. A SSR marker (CSWCT06A)closely linked to cucumber wilt resistant gene was found .Population analysis indicated that among 234 F2 plants,47 resistant plants possessed two fragments which were in accordance with their resistant parent.While the 187 susceptible plants possessed one fragment which was in accordance with their susceptible parent.But there were 2 resistant plants that possessed one fragment and 12 susceptible plants that possessed two fragments.Linkage analysis indicated that the SSR marker was closely linked to cucumber wilt gene,and the genetic distance was 5.98cM.