The Induction and Detection of Novel Allelic Variants of TaAP2 Homoeologs for the Engineering of Cleistogamy in Wheat

Barley cultivars carrying a recessive allele at the cly1 locus are cleistogamous. The florets remain tightly closed throughout the pollination period, thereby ensuring self-pollination and inhibiting access to the host of the fungal pathogen responsible for Fusarium head blight. In hexaploid wheat, a limited number of genetic sources of cleistogamy are known, but the level of cleistogamy they show is incomplete and/or unstable. Based on the understanding that cly1 encodes an AP2 protein and that cleistogamy is induced by a single nucleotide polymorphism in the cly1 miR172 targeting site, our strategy to engineer cleistogamous hexaploid wheat is predicated on introducing the critical polymorphism into each of the three TaAP2 homoeologs which are the orthologs of cly1. Sequence variation within the relevant AP2 genes has been surveyed in a collection of >60 diverse accessions of both Triticum spp. and Aegilops spp. varying in ploidy level, but so far no functional polymorphisms have been identified in their miR172 targeting site. Here we report a current TILLING/EcoTILLING approach to detect miR172 targeting site polymorphisms in each of the three TaAP2 homoeologs.