oryzae (Xoo) is a major biotic

constraint in the intensive irrigated rice belt comprising Punjab and adjoining north-western states of India. Development and deployment of host resistance is the only effective means of BB management. The pathogen is highly variable, and the current Xoo population from the state could be classified into seven distinct pathotypes (PbXo-1 to PbXo-7) by inducing differential reactions on a set of near-isoganic lines in the background of IR24 and some international, national and regional cultivars. Known BB resistance genes (Xa1, Xa3, selleck kinase inhibitor Xa10, Xa11, Xa14, Xa18) were ineffective, whereas xa13, Xa4 + xa13, xa5 + xa13, xa13 + Xa21, Xa4 + xa5 + xa13, Xa4 + xa5 + Xa21, Xa4 + xa13 + Xa21, selleck products xa5 + xa13 + Xa21 and Xa4 + xa5 + xa13 + Xa21 and rice line IET8585/Ajaya were effective against all the seven pathotypes analysed. Xa21 was effective against all the pathotypes except PbXo-3 and PbXo-4. PbXo-7, the most dominant pathotype, was found

to be virulent and induced susceptible/moderately susceptible reaction on 22 of the 40 test genotypes followed by PbXo-1, PbXo-5 and PbXo-6; PbXo-2 was the least virulent pathotype. Molecular profiling of these pathotypes using random amplified polymorphic DNA (RAPD) and IS1112-based polymerase chain reaction (PCR) generated specific and reproducible fingerprint patterns. Primers S1117, S112, S109, S1106 and JEL are more informative in distinguishing pathotypes. At a similarity of 0.50, pathotypes PbXo-1 and PbXo-2 MCE were grouped together, whereas other five pathotypes showed separate lineage. The data using RAPD-PCR and IS1112-based

PCR approaches revealed their potential in generating unique DNA fragments specific for different pathotypes that may lead to the rapid assessment of genetic variation in the pathogen population. Pyramiding of two/more partially effective known Xa genes and/or search for new disease resistance genes effective against the wider Xoo population appears to be the most appropriate approach for BB management in the near future. “
“Migrations or introduction of new genotypes of Phytophthora infestans to a specific region imposes a different perspective for potato production. During 2009–2010, a late blight epidemic affected the Northeastern United States, which quickly spread through several states. The epidemic was characterized by the appearance of a new genotype of P. infestans designated US-22, which was isolated from tomato and potato. Potato tubers are an essential component of late blight epidemics where the pathogen cannot overwinter on Solanaceous plants. Six potato cultivars were inoculated with 12 isolates of P. infestans (five different genotypes), including isolates of the genotype US-22. Tuber blight development was characterized in terms of tissue darkening expressed as area under the disease progress curve values and lenticel infection.