| Wheat stripe rust (yellow rust), caused by Puccinia striiformis West. f. sp. tritic is one of the most important diseases on wheat throughout the world. Planting resistant cultivars is the most effective and economical methods to control this disease. But resistant wheat cultivar gradually lost its resistance traits in several years because of the narrow genetic background. Genetic diversity is the fundamental element of biodiversity, including the genetic differentiation between populations in a species and the genetic variation among individuals within a population. Genetic diversity analysis is helpful for efficient utilization of the germplasm resources and genetic improvement.93 wheat cultivars and advanced lines were assessed for resistance to stripe rust in adult stage by using three prevalent races (CY29,CY31,CY32). Genetic diversity was used to investigate by SSR marker. The main results were as follows:1. 93 wheat cultivars were assessed for resistance to stripe rust in adult stage by using race 31, race32 and mixed races (CY29,CY31,CY32), recorded infection type, severity, and incidence respectively. The results indicated that 30 cultivars were immune and nearly immune to CY31, 57 cultivars were high resistance and moderate resistance, 6 cultivars were medium susceptibility and high susceptibility. To CY32, 29 cultivars were immune and nearly immune, 51 cultivars were high resistance and moderate resistance, 13 cultivars were medium susceptibility and high susceptibility. To mixed races, 21 cultivars were immune and nearly immune, 53 cultivars were high resistance and moderate resistance, 19 cultivars were medium susceptibility and high susceptibility. Overall evaluation of identification result by three times. 16 cultivars were immunity, 50 cultivars were resistance and 27 cultivars were infection.2. 23 primers out of 108 SSR markers in genome A, B and D of wheat were used to investigate the genetic diversity of 93 wheat cultivars. The 23 primers are steady, high resolution and polymorphic amplification profiles. The results showed that 23 SSR primers produced 161 distinctive bands in total and 136 of them were polymorphic, accounted for 84.5%. Each primer amplified 2 to 14 polymorphic bands with the average of 5.9. The value of allelic polymorphism information content (PIC) ranged from 0.54 to 0.93 on an average of 0.78. The greatest PIC was prime wms265 and the smallest PIC was barc18.3. The genetic similarity (GS) among 93 wheat cultivars was calculated according to SSR data.The GS varied from 0.43 to 0.98 with an average of 0.70.The GS between wheat Piotto194.10044 and qingmai978111 was the greatest (0.98), while the GS between wheat kunpeng 1 and xinxiang5407 was the smallest (0.43). The results indicated that lower genetic diversity and narrow genetic basis. Broading the genetic basis become the main problem for plant breeding.4. The result showed that cultivars tested in GS 0.69 were clustered into four groups and six subgroups. There were 13 cultivars in SGI such as shi00-7221, shijiazhuang8, yarmongl9, yarmong2801; 78 cultivars in SGâ…¡; sumai 3 in SGâ…¢and lu959-161 in SGâ…£. SGâ…¡was divided into 6 subtypes. The first subtype contained 6 cultivars such as shi01-5111, ji7369, The second subtype contained 50 cultivars such as lunxuan136, lunxuan978, jinan17, kangbai 2, The third subtype contained 9 cultivars such as 95 zhong 489, jingwang10, The forth subtype contained 9 cultivars such as GB2064, jingdong 8, jingnong02-56, The fifth subtype contained fenshou60, zheng366. The sixth subtype contained 96 zhong43. This is partly accordance with the previous classification. A few cultivars (line) in the same or similar pedigree didn't clustered together.
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