The Ta-Lr34res gene confers partial, durable, and broad spectrum resistance
against several fungal pathogens in wheat (Triticum aestivum). Transgenic
barley (Hordeum vulgare) lines expressing Ta-Lr34res showed enhanced
resistance against powdery mildew and leaf rust. While the gene is only
active at adult stage in wheat, Ta-Lr34res was found to be already highly
expressed at the seedling stage in transgenic barley, resulting in severe
negative effects on growth.

To solve this, University of Zurich researchers expressed Ta-Lr34res under
the control of the pathogen-inducible Hv-Ger4c promoter in barley. The
resulting transformants showed strong resistance against leaf rust and
powdery mildew. The transformed events also had similar grain production
compared to susceptible wild types.

These results showed that negative effects caused by early high expression
of Ta-Lr34res can be eliminated by inducible expression without compromising
disease resistance.

[onlinelibrary.wiley.com]