| Wheat stem rust was a long distance air-borne disease with high specialization occurring all over the world. Since the1950s, thanks to the concerted efforts of the national researchers, genetic control methods were applied based on clarifying the mode of transmission and epidemic of the disease, location of source areas for overwintering and over summering. Lots of measures were utilized, according to the population dynamics and virulence variation, such as carrying out anti-source germplasm screening, exploring new genes, cultivating and promoting resistant varieties, distributing resistance variations (genes) properly and controlling bacteria source bases.It contributed that no severe epidemic had occurred widely in China since the1970s. However, new race Ug99appeared in Uganda in1999made the resistance gene Sr31used worldwide loss resistance.What worse, it continue to evolved new mutant strains with wider virulence spectrum and tend to rapidly spread to other wheat producer in the world and cause severe epidemic, shooking the relevant scientists of plant pathology and wheat breeders. Then the worldwide Global Rust Research Collaboration was established led by the Nobel laureate N. E. Dr. Borlaug for carrying out the genetic-based technology to control Ug99worldwide and then preventing the epidemic broking out again in the world. In the study, the population dynamics of Puccinia graminis f. sp. tritici was detected. Resistance of part of national wheat varieties and the resistant source materials against Ug99were initially analyzed. Additionally, molecular detection of part of national cultivars was carried out for detecting the resistance genes to Ug99.1. Monitoring and analysis for the wheat stem rust and invasion of Ug99in2013A total of53single-pustules obtained from22samples generated through sexual cycle and11samples collected from the major wheat stem rust epidemic areas were isolated and identified using the latest complex differential host system. Four race groups including13physiological races were identified (Ug99was not contained), which included the most prevalent races34C3RTGQM and340roII-MRGQM at13.2%predominance, followed by race34MRGQM at11.3%. Six new races having virulence to Sr5+Srll were found for the first time in China and five of the six were isolated from samples experiencing sexual cycle. Virulence tests to Sr single genes indicated that these race groups were avirulent Sr9e, Sr26, Sr31, Sr38, Sr47and SrTt3, while virulent to one or more of the other remaining single genes. 2. Resistent source screening of wheat varieties in China and germplasm resistant to Ug99Seedling resistance of123international materials resistant to Ug99were identified using the predominant races of China,21C3HTTTM,34C3RTGQM and34MRGSM.The results showed that there were85wheat varieties having different degrees of resistance to all the stem rust races tested. These cultivars were resistant to Ug99and mainly national races simultaneously and can be used as future breeding resistant parent materials.226of the332national wheat cultivars tested showed good resistance to all the races tested with proportion68.1%.31.9%of the cultivars were infected with different degrees, indicating that there are still large numbers of cultivars easily infected by stem rust. Additionally, remarkable resistant differences exist in wheat cultivars from different regions. Totally, the resistance of variations in southern regions was superior compared with the northern regions.3. Analysis for cultivars resistance to stem rust of wheat varieties in Yunnan ProvinceTo appraise the resistance level of the wheat cultivars to wheat stem rust in Yunnan Province,102wheat cultivars and68native varieties had been analyzed for their resistances to two experimental races21C3CTHQM,34MKGQM and mixed physiological races of wheat stem rust at adult stage during2012-2013. The result indicated that65wheat cultivars such as Fengmai39, Jingmai10, Yumai3and3landraces includingYun0072, Yun0300and Yun0205were resistant to wheat stem rust, which accounted for63.7%and4.4%.According to the identification result of the resistance at adult stage,110cultivars having different resistances were selected.11native races of Puccinia graminis f. sp. tritici with different virulence and one foreign race (not Ug99) virulent to Sr31were used for postulating the resistance genes of wheat varieties (lines) in Yunnan Province. The results indicated that among the45known resistance genes, Sr31, Sr5, SrTmp, Sr30, Sr36were characterized in these wheat varieties singly or with combination. Sr5was the most postulated gene carried by17cultivars and Sr31was the second and presented in16cultivars. Additionally, five wheat varieties were likely screened to contain resistant genes SrTmp virulent to Ug99, namely Guoji13, Wen06-3, De07-20,098-4and098-2. No relevant reports were found in the past.4. Molecular detection for resistance genes in part of national wheat cultivars and germplasm resistant to Ug99from CIMMYTTo screen and identify anti source materials with good resistance the new race Ug99of Pgt, the reported molecular markers tightly linked to the race Ug99effective stem rust resistance genes Sr22, Sr25, Sr26and Sr28were applied for the test of China and283wheat varieties in China and20accessions from CIMMYT.The results showed that no Sr22was detected in all the tested materials; Sr25and Sr26were not detected in the national wheat varieties. However, Sr25and Sr26were detected to be possibly contained in the germplasm resistant sources MXI10-11\M6SR-RSN\10and MXI10-11\M6SRRSN\13and MXI10-11\M6SRRSN\6from CIMMYT, respectively. Additionally, Sr28was likely contained in MXI10-11\M6SRRSN\3, MXI10-11\M6SRRSN\5and MXI10-11\M6SRRSN\20, Yunmai47, Nanyuan1, Jingmai05-1, Shannong15, Linmai15and Jingmai10.5. First report on race and virulence characterization of Puccinia graminis f. sp. avenae and on resistance appraisal of oat cultivars in ChinaTo unveil current physiological races and virulence patterns of Puccinia graminis f. sp. avenae(Pga) and to provide guidance for screening of germplasm for stem rust resistance and setting goals of resistance breeding, races of Pga were for the first time characterized in China.12single Pg gene differentials of oat used in North America were applied to race identification at seedling stage using Pga samples collected in oat growing areas in China in2013. The three-letter Pga code nomenclature system was followed to name the races. The results showed that26isolates isolated from11accessions were identified for3races, namely TKR, TJM and TKM. Their occurrence frequencies were61.6%,30.8%and7.6%, respectively. It was also indicated that virulence frequency on both Pg6and Pg15was zero, but on Pgl, Pg2, Pg3, Pg4, Pg8, Pg9, Pg12, Pg16and Marvellous, up to100%and on Pg10, Pg13, Pga and Rodney0, up to69.2%,61.6%,61.6%and84.6%respectively. Three races were found out in the China’s Pga population. Resistances to stem rust of35oat cultivars were analyzed with the three races TKR, TJM and TKM, showing only37.1%of the oat cultivars had resistance. |
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