Silencing of RBOHF2 causes leaf age-dependent accelerated senescence, salicylic acid accumulation and powdery mildew resistance in barley

Plant RBOH (RESPIRATORY BURST OXIDASE HOMOLOGUES)-type NADPH oxidases produce superoxide radical anions and have a function in developmental processes and in response to environmental challenges. Barley RBOHF2 has different reported functions in interaction with the biotrophic powdery mildew fungus Blumeria graminis f.sp. hordei. Here we analysed in detail, plant leaf level- and leaf age-specific susceptibility of stably RBOHF2-silenced barley plants. This revealed enhanced susceptibility to fungal penetration of young RBOHF2-silenced leaf tissue but strongly reduced susceptibility of older leaves when compared to controls. Loss of susceptibility in old RBOHF2-silenced leaves was associated with spontaneous leaf tip necrosis and constitutively elevated levels of free and conjugated salicylic acid. Additionally, these leaves more strongly expressed pathogenesis-related genes both constitutively and during interaction with B. graminis f.sp. hordei. Together, this supports that barley RBOHF2 contributes to basal resistance to powdery mildew infection in young leaf tissue but is required to control leaf cell death, salicylic acid accumulation and defence gene expression in older leaves, explaining leaf-age-specific resistance of RBOHF2-silenced barley plants.     «

Plant RBOH (RESPIRATORY BURST OXIDASE HOMOLOGUES)-type NADPH oxidases produce superoxide radical anions and have a function in developmental processes and in response to environmental challenges. Barley RBOHF2 has different reported functions in interaction with the biotrophic powdery mildew fungus Blumeria graminis f.sp. hordei. Here we analysed in detail, plant leaf level- and leaf age-specific susceptibility of stably RBOHF2-silenced barley plants. This revealed enhanced susceptibility to fun...     »