Lr34 has been used in wheat breeding for over a hundred years, as it confers durable broad-spectrum resistance against multiple fungal diseases. UZH researchers are studying how this ‘resistance gene of the century’ functions, and how it could be deployed in barley and maize. Their studies on the Protected Site showed that GM barley with a strong Lr34 gene expression was fully protected from barley leaf rust (P. hordei) and powdery mildew (B. graminis f.sp. hordei), even under field conditions. However, these GM barley plants produced smaller seeds due to a “side effect” of Lr34, leaf-tip necrosis (LTN), which also occurs in wheat. Barley plants with a weaker Lr34 expression were only partially protected from leaf-rust infection, but had no LTN and no yield penalty. The researchers demonstrated that the redistribution of the phytohormone abscisic acid (ABA) in the leaves correlates both in the greenhouse and under field conditions with the production of LTN, and that this redistribution is only measurable in plants with strong Lr34 gene expression. Thanks to these results, not only has our understanding of Lr34’s resistance mechanism improved, but the authors have also shown that by optimising Lr34 gene expression level a good balance between disease resistance and LTN could be achieved, which would enable the deployment of this valuable wheat gene in barley breeding programmes.
Publication (open access):
Bräunlich S.; Koller T.; Glauser G.; Krattinger S.G.; Keller B. Expression of the wheat disease resistance gene Lr34 in transgenic barley leads to accumulation of abscisic acid at the leaf tip. Plant Physiology and Biochemistry 2021, 166, 950-957. https://doi.org/10.1016/j.plaphy.2021.07.001
31.03.2021. The Federal Office for the Environment (FOEN) authorised the University of Zurich to conduct an experimental release of genetically modified wheat lines with improved powdery mildew resistance. It is a complement to the field trials authorised in 2019.
6.01.2021. Since 2014, University of Zurich (UZH) researchers have been conducting field trials on the Protected Site at Agroscope Reckenholz with genetically modified (GM) wheat with improved powdery-mildew resistance conferred by Pm resistance genes from wheat (description of the project. In order to expand their research questions, they want to sow in the current trials some of the genetically modified wheat lines that had already been released previously. Since the authorisation for these plants had expired in 2018, they submitted a new release application (in German) for these wheat lines to the Federal Office for the Environment (FOEN). The UZH proposes to implement the same safety measures imposed on them by the FOEN in the current field trial. In the coming weeks, the FOEN will examine the application as well as the comments and opinions received and will probably decide in spring whether to approve these wheat lines for field trials again.
Further information on the project with powdery mildew-resistant wheat
