Discoloration of wheat kernels by Pyrenophora tritici-repentis

Infection of wheat kernels by Pyrenophora tritici-repentis (Ptr) causes pri marily a pink/red discoloration. Dark smudge and black point are also commo nly observed. These types of kernel discoloration cause downgrading of whea t. A series of studies on Ptr-kernel infection are summarized here. Infecte d durum wheat kernels germinated faster than uninfected ones, but seedlings derived from the former had reduced vigour. Emergence of plants derived fr om infected seed was also reduced. However, no transmission of Ptr-infectio n from seed to emerging durum wheat seedlings was observed. Studies on duru m wheat also showed that there was no association between discoloration of glumes and discoloration of kernels, or between tan spot development on lea ves and discoloration of kernels. Wheat cultivars of different quality clas ses and species showed differences in the prevalent type of symptom develop ed upon inoculation with Ptr. In addition, the incidence and severity of th e discoloration were genotype-dependent, and the discoloration was more app arent in white than in red-seeded cultivars. A study examining the effect o f incubation conditions on the development of kernel discoloration caused b y Ptr in durum wheat indicated that the length of incubation period mainly affected the severity of infection, whereas temperature of incubation affec ted percent kernel infection, including development of black point.