HvSRP72 silencing enhanced Blumeria graminis f. sp. hordei growth in compatible interaction with barley

Abstract

Powdery mildew disease, caused by Blumeria graminis f. sp. hordei (Bgh), is one of the important diseases of barley. Hordeum vulgare Signal Recognition Particle 72 (HvSRP72) was previously identified as differentially induced at 6h and/or 12h after infection in powdery mildew disease resistance, suggesting its involvement in pathogen response. Since there is limited information on R gene-mediated signaling cascade, we sought to understand the way which HvSRP72 protein functions in powdery mildew resistance or susceptibility response. HvSRP72 was silenced by barley stripe mosaic virus (BSMV)-induced gene silencing, in order to understand its role in the plant response to pathogen infection. The level of HvSRP72 mRNA in silenced plant samples showed an average 57% reduction with respect to control plants (BSMV:00). The change in resistance or susceptibility to powdery mildew in HvSRP72-silenced plant leaves was determined by measuring the length of hyphal extensions and the germination efficiency upon inoculation. Under susceptible conditions, in HvSRP72-silenced samples spores germinated approximately four times more efficiently and Bgh development was also increased twice with respect to control plants. On the other hand, under the resistant condition, no difference was observed in HvSRP72-silenced samples when compared to the non-silenced ones. Thus, it can be concluded that silencing of HvSRP72 enhances Blumeria graminis f. sp. hordei susceptibility but no change of hyphal growth was observed during resistance response.