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.

[onlinelibrary.wiley.com]