Hyperspectral and molecular analysis of Stagonospora nodorum blotch disease in durum wheat

Stagonospora nodorum blotch (SNB) is an important wheat disease caused by Parastagonospora nodorum (Berk.) Studies in Mycology, 75: 307–390 (2013). This necrotrophic pathogen can attack common and durum wheat, causing grain yield, quality and safety worsening. This work aims to studying a novel diagnostic technique for early detecting P. nodorum attack and infection progression in three Italian commercial varieties of durum wheat. Plants of these wheat varieties were inoculated in field with a spore suspension of P. nodorum. Different experimental conditions were used: P. nodorum was inoculated in plants at different growth stage (GS); GS32 (Inf A) and GS 73 (milk development - Inf B). To consider natural contaminating mycoflora interference for the subsequent analysis, noninoculated controls, fungicide-treated (T) or non-treated (NT) were used. Inf A produced symptoms both on leaves and ears which appeared to be more severe compared to those induced by Inf B, even if the latter affected more thoroughly wheat yield in at least one variety of wheat. An early detection of SNB could be helpful to manage a targeted control strategy. Hyperspectral imaging analyses showed that this rapid and non-invasive technique allows differentiation between spectra of healthy and diseased tissues already 48 h after inoculation. qPCR confirmed hyperspectral results. The results showed that marked differences emerge in the ability of the varieties to tolerate the SNB disease especially regarding grain yield and quality. Compared with classical approaches, the hyperspectral imaging analysis may represent a useful tool for early detection of P. nodorum on wheat.