A TRIM insertion in the promoter of Ms2 causes male sterility in wheat

The first dominant male-sterile mutant in wheat, ms2 was identified more than 40 years ago, and Xia et al. have now identified the molecular basis for this trait. They find that the mutation is caused by a transposon (a terminal-repeat retrotransposon in miniature, or TRIM) insertion into the promoter of the Ms2 gene, causing it to be specifically expressed in anthers. The protein encoded by the Ms2 gene has no known functional domains, and only has homologues in the diploid ancestor of wheat, and tetraploid and hexaploid wheat, but functional analysis indicates that it is the cause of the male-sterile phenotype. The authors summarize, “The identification of Ms2 not only unravels the genetic basis of a historically important breeding trait, but also shows an example of how a TRIM element insertion near a gene can contribute to genetic novelty and phenotypic plasticity.” Nature Comms. 10.1038/ncomms15407