Idetification Of Wheat Resistance To Fusarium Head Blight(FHB) And QTL Analysis Preliminary Location

Fusarium head blight(FHB), caused by Fusarium graminearum Schwab(telomorph:Gibberella zeae), is a major disease of wheat. Out break of FHB can result in devastating economic losses to wheat production, since it not only lowers the yield but also deteriorates the quality of wheat grains. Deployment of scab-resistant varieties is the most economical measure in controlling this disease. However, the paucity of germplasms and lack of knowledge about the resistance genetics have greatly limited the progress in scab resistance breeding. Therefore, it is the main contents of research on Fusarium head blight (FHB) to dig out and locate new resistance gene. There is rich resistant germplasm in intraspecific and extraspecific of wheat. It is the premise of breeding for scab resistance that how to identify and select wheat scab resistant germplasm. The development of molecular marker technique and perfection of mapping methods of QTLs as a basis for developing the genetic analysis of resistance to wheat scab.In this study, rice stubble was collected for isolation, purification and identification of Fusarium graminearum Schw. Two Fusarium species were identified according to Nierenberg and Booth classification standards. There were F. graminearum Schw. and Fusarium culmorum that used in study on identification of wheat resistance to scab.The resistance test of 162 wheat varieties (lines) from triticeae research institute were conducted in the field. Results showed that there were no immunological and highly resistant wheat varieties (lines). Among them, wheat varieties (lines) showed MR account for 6.79% of tested cultivars (lines), showed MS account for 7.41% of tested cultivars (lines), showed HS account for 82.72% of tested cultivars (lines). There was a very significant difference (P<0.01) among different wheat varieties (lines).50 wheat varieties (lines) were selected from 162 wheat varieties (lines) was used to mycotoxin by means of suppression of radical growth and so on was tested in the laboratory, according to method which was proposed by Siheng Liu (1989). Results showed that root growth, bud growth and root number of resistant varieties and susceptible ones were significantly inhibited, but it has little influence on resistant varieties and has great influence on susceptible ones. There was a very significant difference (P<0.01) with mycotoxin to act on wheat root and wheat malt.In coleoptiles inoculation, Results showed that tissue became brown at the inoculation site after 3 days. Extended browning spot symptom is very clear after 7days. The length of browning spot showed extremely significant difference (P<0.01), It indicated that the length of browning spot could be used as identification index about epidemic degree of shoots of wheat.System comparison and negative correlation was observed between inoculation in flowering stage and inoculation with crude toxin produced by Fusarium Graminearum and coleoptiles inoculation. It showed that the results had quite closely linear relationship (P<0.01) both methods of inoculation in budding and inoculation identification indoor. Correlation coefficient was 0.282 and 0.461 respectively. Identification result indoor was in high correlation with identification result in the field. So it showed that identification of wheat resistance to Fusarium Head Blight (FHB) was more accurate.To identify the resistance gene to Fusarium head blight (FHB) and employ molecular markers associated with the resistant gene for marker-assisted selection, quantitative traits loci (QTL) of FHB resistance in Wangshuibai/SY95-7 F₂ population had been characterized with simple sequence repeats (SSR).At first, the SSR molecular tagging of QTL for scab resistance in wheat was carried with Wangshuibai/SY95-7 F₂ population. The results showed as follows, of the 696 microsatellite primers screened, 125 SSR primers had polymorphism between Wangshuibai and SY95-7.Among them there were 21 SSR primers that showed the same polymorphism both in the resistance pools and sensitive pools and two parents. Pass by association analysis of molecular markers and data of resistance and interval mapping, which indicated that there were QTLs of scab resistance among on chromosome 7A, 6B, 3B, and 2D, 1B, between Xwmc168-7A-Xwmc479-7A, Xwmc486-Xwmc737-6B, Xwmc623-3B-Xwmc231-3B, Xwmc134-1B-Xwmc134 and Xwmc134-1B-Xwmcl34 respectively.