Wheat blast: Aggressiveness of isolates of Pyricularia oryzae and effect on grain quality

Abstract

Four wheat cultivars commonly used in Argentina displayed different pattern of reaction depending of the Pyricularia oryzae isolate inoculated, according to the observed lesions and type of reaction both on seedlings and spikes of the plants tested grown under greenhouse conditions. At seedling stage, Buck Meteoro showed a susceptible reaction with seven of the eight isolates tested (phenotypic reaction 3 and 4). On the contrary, Baguette 11 showed a resistant reaction with most of the isolates tested (phenotypic reaction 1 and 2). At heading stage, cultivars Klein Proteo and Baguette 11 showed the greatest susceptibility to P. oryzae (more than 95% severity with isolates ArW22 and ArR1). On the contrary, low disease severity was shown in ACA 303 particularly in combination with isolates ArR3, ArR4, BrW27 and BolW8 with mean values of 2.18%–11.50%. The results indicate variation in aggressiveness among P. oryzae isolates evaluated. A low negative correlation between seedling disease severity and spike disease severity was found. The 1000-grain weight was negatively correlated with spike blast severity. Reduction values induced by each isolates ranged from 18.53% to 74.94%. ACA 303 showed the highest reduction in 1000-grain weight. The lower weight registered, in the most affected genotype ACA 303 infected with ArR2, was of 9.32 g. Protein extractability was higher in Wheat blast (WB) infected grains compared to the control healthy wheat. Protein values increased with the increasing severity of WB infection demonstrating P. oryzae interfered with the grain protein profile, thereby altering the grain protein content and quality.