March 27, 2014
Speaker to discuss winter wheat disease
Submitted by Stephanie Alvord-Albanese
Liuling Yan, Oklahoma State University, will present "Can Lr34 resistance to leaf rust be upgraded in winter wheat?" at 3:45 p.m. March 27 in 4031 Throckmorton Hall.
The lecture abstract is:
Lr34 is a non-race-specific gene that confers durable resistance against several diseases including leaf rust, stripe rust, stem rust, and powdery mildew, as well as barley yellow dwarf virus. Allelic variation in Lr34 in winter wheat relies, in part, on a G/T polymorphism that was found in exon 22, where a premature stop codon occurs in the susceptible allele due to a point mutation. In all, three polymorphic sites were reported in intron 4, exon 11, and exon 12 of Lr34 in spring wheat. In a cultivar carrying the resistant Lr34 allele, only a portion — 35 percent — of its transcripts may be correctly spliced. Abnormalities in splicing can be identified as multiple intron retention or exon skipping events, and most of the mis-splicing events result in truncated proteins. These findings indicate the potential of producing more functional transcripts from the resistant Lr34 allele. In normal wheat, only Lr34 on homoeologous chromosome 7D confers a measurable phenotype for durable resistance to leaf rust. However, added expression of Lr34 is conceivable by increasing the copy number of Lr34 in a winter wheat cultivar that already carries a resistant allele, i.e., by producing transgenic wheat that has two copies of Lr34. The copy number of Lr34 can also be doubled by deploying a duplicated Lr34 copy that was recently found in a unique hard red winter wheat cultivar. These approaches may be integrated to generate more functional Lr34 copies and thereby upgrade Lr34 resistance in wheat.