Gene Loss, Silencing and Activation in a Newly Synthesized Wheat Allotetraploid

We analyzed the events that affect gene structure and expression in the early stages of allopolyploidy in wheat. The transcriptome response was studied by analyzing 3072 transcripts in the first generation of a synthetic allotetraploid (genome S(l)S(l)A(m)A(m)), which resembles tetraploid wheat (genome BBAA), and in its two diploid progenitors Aegilops sharonensis (S(l)S(l)) and Triticum monococcum ssp. aegilopoides (A(m)A(m)). The expression of 60 out of 3072 transcripts was reproducibly altered in the allotetraploid: 48 transcripts disappeared and 12 were activated. Transcript disappearance was caused by gene silencing or by gene loss. Gene silencing affected one or both homeologous loci and was associated…