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Liang Y.,CAS Wuhan Botanical Garden | Liang Y.,University of Chinese Academy of Sciences | Zhang Z.,Key Laboratory of Integrated Pest Management on Crops in Southwest China | Peng Y.,Key Laboratory of Integrated Pest Management on Crops in Southwest China | And 4 more authors.
Journal of Food, Agriculture and Environment | Year: 2013

Wild emmer wheat (Triticum dicoccoides) is the progenitor of domesticated wheat and harbors a valuable pool of resistance genes that can be transferred into cultivated wheat. However, little is known about their response to Chinese stripe rust population of Puccininia striiformis f. sp. tritici, which has caused severe yield lost and huge input of pesticides into the environment. In this study, 311 T. dicoccoides genotypes representing 31 populations from the Fertile Crescent were planted in the disease nursery located at Yanting, Sichuan Province of China. We used these genotypes to investigate the virulence composition of the fungal population and the infection types on wild emmer wheat at the seedling and adult stages. The main virulence types of the pathogen at the disease nursery were CY32 and CY33, the most virulent and prevailing race in China. Newly emerged mutant virulent to Yr24 was also detected at a low frequency of 2.17%. Among the 311 genotypes tested, 17 genotypes out of 7 populations demonstrated whole stage resistance to yellow rust. Fifty-six genotypes out from 19 populations were susceptible at the seedling stage but with shown resistance at the adult stage. Water and temperature variables at the places of origin of populations were found to be correlated with the infection types at the disease nurseries. Therefore, wild emmer wheat is a valuable resistance source for China wheat breeding programs against the yellow rust disease.

BAI Y.-L.,Key Laboratory of Integrated Pest Management on Crops in Southwest China | BAI Y.-L.,Sichuan Agricultural University | ZHANG X.-M.,Key Laboratory of Integrated Pest Management on Crops in Southwest China | ZHANG X.-M.,China National Rice Research Institute | And 6 more authors.
Rice Science | Year: 2012

A total of 638 isolates of rice blast (Magnaporthe oryzae) were isolated in 2002-2009 from different rice varieties in different regions of Sichuan, China and inoculated onto seven rice varieties (Lijiangxintuanheigu, IR24, Minghui 63, Duohui 1, Chenghui 448, Neihui 99-14 and RHR-1) to differentiate the virulence types of the fungus and trace the changes. The virulence to the seven varieties was respectively scored at 1, 2, 4, 8, 16, 32 and 64. The total scores of individual M. grisea isolates which were the sum of scores infecting differential varieties could, in turn, be used for the nomenclature of the virulence types due to their accordance to the special virulence patterns. The 638 tested isolates were then differentiated into 56 different virulence types. Type 15 virulent to Lijiangxintuanheigu, IR24 and Minghui 63, and Type 127 virulent to all of the seven varieties were the most dominant virulence types respectively with the occurrence frequencies of 15.99% and 15.83%. Type 19 and other seven virulence types were not monitored during 2002-2009. Type 15 was the predominant virulence type in 2002, 2003, 2004 and 2007, whereas Type 127 had been the most dominant virulence type after 2005 except for the year 2007 when the province underwent severe drought. Five hundred and seven out of the 638 tested isolates were virulent to Minghui 63, and 89.58% of the 384 isolates virulent to either Duohui 1, Chenghui 448 or Neihui 99-14 were virulent to Minghui 63, which indicated the impact of the extensive plantation of hybrid rice Minghui 63 as the restorer line on the virulence evolution of M. oryzae in Sichuan. The virulence pattern of the dominant virulence types suggested that the acquiring of virulence to all the major resistant restorer lines was the main routes of the evolution in virulence of M. oryzae to hybrid rice in Sichuan. The virulence frequencies of the 638 tested isolates to IR24, Minghui 63, Duohui 1, Chenghui 448, Neihui 99-14 and RHR-1 were respectively 74.6%, 79.5%, 73.8%, 37.0%, 39.0% and 40.4%. The analysis for the sources of the different virulence type isolates indicated the pathogen on the newly released resistant varieties were stronger than conventional rice varieties which had become susceptible in the field since 1980s. © 2012 China National Rice Research Institute.

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