Host-Induced Gene Silencing of PsCPK1 in Pathogen Enhances Stripe Rust Resistance in Wheat

Rust fungi are devastating plant pathogens on wheat production. In hopes of controlling the pathogen, the team of Northwest A&F University researcher Tuo Qi generated stable transgenic wheat plants expressing short interfering RNAs (siRNAs) targeting potentially vital genes of Puccinia striiformis f. sp. tritici (Pst), the causal organism of wheat stripe rust.

The team targeted PsCPK1, a gene from Pst which is highly induced at the early infection stage. The knock-out of PsCPK1 via host-induced gene silencing (HIGS) resulted in a significant reduction in the length of infection hyphae and disease phenotype. These results indicate that PsCPK1 is an important pathogenicity factor in regulating Pst growth and development.

Two susceptible lines were then transformed, now expressing the RNA interference (RNAi) construct. The transgenic wheat cultivar displayed high levels of stable and consistent resistance to Pst throughout the T₃ to T₄ generations. The presence of the interfering RNAs in transgenic wheat plants was confirmed by northern blotting, and these RNAs were found to efficiently downregulate PsCPK1 expression in wheat.

This study reveals that the expression of silencing constructs in host plants can be a powerful strategy to control cereal rust diseases.

For more on this study, read the article in Plant Biotechnology Journal.