Utilization Of Toxin For Identifying Cotton Resistance To Verticillium Wilt And Genetic Analysis

Verticillium wilt is a soil-borne disease, and it causes the most devastating diseases in cotton all over the world. Verticillium dahliae have a wide geographical distribution, wide host range and disseminated by many ways, the long survival time and so on. It is restricted to use Verticillium fungus to identify the resistance to Verticillium wilt in cotton in the field. Breeding resistant varieties is the most simple, economical and effective method in controlling Verticillium wilt. The most important part of breeding resistant varieties is identifying the resistance to Verticillium wilt in cotton. The identification of resistance to Verticillium is the foundation of screening resistant germplasm resources and studying the genetic analysis of resistance to Verticillium in cotton.In order to replace traditional method, which is used Verticillium pathogen to identify the resistance. We found a new method for identifying the resistance to Verticillium wilt by using Verticillium toxin. We also made a cluster analysis to sort the cotton resistance in field. Moreover a genetic analysis of Verticillium resistance was made in this study. The results are as follows:l.The antepenultimate leaves were collected during the full-bloom stage of cotton, and they were cut to about10-20small leaf discs (the diameter is1.5cm) by hole puncher. Whereafter it was put in the toxin of Verticillium, and counted the disease indexes and yellowing degree after24h. Comparing with conventional method, the correlation coefficient of soaking the leaf disc with toxin is higher through the experimental results in2013and2014. In2013and2014, the correlation coefficient was0.92and0.91respectively. It shows that using soaking the leaf disc with toxin is a feasible accurate method to identify the Verticillium resistance of cotton.2.1n order to identify the cotton resistance to Verticillium wilt more accurately, we combined soaking the root with toxin and soaking the leaf disc with toxin to identify the cotton Verticillium resistance in this paper. Compared with conventional method, the correlation coefficient of combined approach was higher through the experimental results in2013and2014. In2013and2014, the correlation coefficient was0.94and0.95respectively. Compared with reported methods, the combined method is more accurate and reliable than using single method. And it supplied a new idea to identify the disease resistance of other crop.3.We used conventional method and new method (soaking the leaf disc with toxin) to identify the cotton resistance to Verticillium in the field in2013and2014. And we made a cluster analysis according the cotton disease index of bud stage, full-bloom stage and boll opening stage. And it could be classified three types which were disease resistant types, disease tolerant type and disease susceptible types.4.For analyzing the inheritance of Verticillium resistance, The method, soaking the root with toxin, was used in this paper. The Verticillium toxin of V97、V02df and V02were used to infected the three cross, which were61031AxFG1224,61031AxCT1244-3and61031AxFG1268. The results shows that the resistance to toxin of Verticillium was influenced by poly-gene and two pairs of major-gene in the three types. And each cross genetic effect of major-gene and poly-gene were different in different periods.