Pm3 from wheat confers resistance to powdery mildew caused by fungal
pathogen Blumeria graminis f.sp. tritici (Bgt). Researchers have identified
17 working Pm3 alleles that confer resistance to Bgt isolates. One of the
variants, Pm3e, was found in wheat donor line W150 and similar to
non-functional variant Pm3CS except for two amino acids. To evaluate the
capability of Pm3e to confer powdery mildew resistance, scientists from the
University of Zurich and Agroscope in Switzerland developed transgenic Pm3e
lines by biolistic transformation of the powdery mildew susceptible spring
wheat cultivar Bobwhite.
Results of the field trials showed significant and strong powdery mildew
resistance of the Pm3e transgenic lines, while the non-transformed lines
were severely powdery mildew infected. Thus, it was confirmed that Pm3e
alone is responsible for the strong resistance phenotype. The field grown
transgenic lines showed high transgene expression and Pm3e protein
accumulation with no fitness costs on plant development and yield associated
with Pm3e abundance.
Based on the study, Pm3e can provide strong powdery mildew field resistance,
making its use in wheat breeding programs very promising.