An Efficient System for Ds Transposon Tagging in Brachypodium distachyon

Transposon tagging is a powerful tool that has been widely applied in several species for insertional mutagenesis in plants. Several efforts have aimed to create transfer-DNA (T-DNA) insertional mutant populations in Brachypodium distachyon, a monocot plant used as a model system to study temperate cereals, but there has been a lack of research aimed at using transposon strategies. Here, we describe the application of a maize (Zea mays) Dissociation (Ds) transposon tagging system in B distachyon The 35S::AcTPase cassette and Ds element were constructed within the same T-DNA and transformed into B distachyon plants. The Ds element was readily transposed to other chromosomes or to the same chromosome under the function of Activator (Ac) transposase. Through homologous chromosome synapsis, recombination, and segregation, the Ds element separated from the Ac element. We selected stable Ds-only plants using G418 and GFP assays and analyzed 241 T₀ lines, some of which were highly efficient at producing Ds-only progeny. Through thermal asymmetric interlaced PCR, we isolated 710 independent Ds flanking sequences from Ds-only plants. Furthermore, we identified a large collection of mutants with visible developmental phenotypes via this transposon tagging system. The system is relatively simple and rapid in comparison to traditional T-DNA insertion strategies, because once efficiency lines are obtained they can be reused to generate more lines from nontransposed plants without the use of time-consuming tissue culture steps.