MicroRNA misregulation: an overlooked factor generating somaclonal variation?

Somaclonal variation is an important phenomenon that can be observed at high levels in plant tissue culture. Although known to science since plant cell culture techniques were first developed, its origins remain mysterious. Here, we propose that misregulation of microRNAs and small RNA pathways can make a significant contribution to the phenomenon. For many reasons, microRNAs and related small RNAs appear ideal candidates. Their mode of action gives them disproportionate influence over the transcriptome, proteome and epigenome. They regulate important developmental and physiological events such as meristem formation, phase changes and hormone responses. However, the genomic locations of microRNA genes and their unique biogenesis might make them unusually susceptible to aberrant regulation in vitro.