02311nam a2200169 a 450000100080000000500110000800800410001910000180006024501110007826001940018952016710038365300180205470000200207270000170209270000160210970000160212519342652012-09-21       2012    bl uuuu     u00u1 u    #d1 aSOARES, R. M.  aPathogenicity of soybean rust populations in Brazil 4 cropping seasons 2007 - 2011.h[electronic resource]  aCONGRESSO BRASILEIRO DE FITOPATOLOGIA, 45., 2012, Manaus. [Anais...]. Tropical Plant Pathology, Brasília, DF, v. 37, Aug. 2012. Suplemento. Trab. 358, Micologia. 1 CD-ROM. Fito 2012.c2012  aSoybean rust caused by Phakopsora pachyrhizi is one of the most serious threats to soybean production in Brazil. In this study, we evaluated pathogenicity of the 7 rust samples collected in Brazil in the 2010/11 season based on infection types produced on 16 differential varieties, and compared them with those in 3 seasons of 2007/08?2009/10. When the data were classified into 3 categories: susceptible, intermediate, and resistant, none of the 7 samples from the 2010/11 season showed identical pathogenicity profile in the differentials. Cluster analysis and principal coordinate analysis revealed that 31 rust samples from the 4 seasons vary geographically and temporally in pathogenicity. The cluster analysis divided the 31 samples into 2 groups (A and B), and the 7 samples from the 2010/11 season were scattered throughout in both groups. The frequencies of susceptible reaction produced in differentials 3?6, 9, 10, and 12 were significantly higher for group A than for group B. The differentials containing resistance genes Rpp1, Rpp2, Rpp3 and Rpp4, except for PI 587880A, displayed resistant reaction to only &lt13%, &lt39%, 23%, and 38% of Brazilian rust populations, respectively. In contrast, PI 587880A (Rpp1), Shiranui (Rpp5), and 3 Rpp-unknown differentials PI 587855, PI 587905, and PI 594767A, showed resistant reaction to 74%?96% of the populations. This study demonstrated that (i) pathogenicity of P. pachyrhizi populations was diverse in Brazil in the 4 seasons, (ii) Brazilian populations of group A were more virulent than those of group B, and (iii) 5 differentials have been effective against recent pathogen populations in the country.  aFitopatologia1 aAKAMATSU, H. O.1 aYAMANAKA, N.1 aYAMAOKA, Y.1 aSUENAGA, K.