Epigenome Editing Enhances Resistance Against CBB

A novel method published by scientists from the United States describes an epigenetic modification they successfully developed to increase resistance against the cassava bacterial blight (CBB) disease. The approach also has the potential to be effective in other crop species.

A plant becomes affected by CBB when its causal agent, Xanthomonas phaseoli pv. manihotis, affects the plant's S gene called MeSWEET10a by activating the transcription activator like 20 (TAL20). Based on this, the scientists investigated the effects of the direct methylation to the TAL20 effector binding element within the MeSWEET10a promoter using a zinc finger DNA binding domain combined with a component of the RNA-directed DNA methylation pathway. They found that the methylation was able to prevent the binding of the TAL20 while blocking the transcriptional activation of MeSWEET10a in vivo. They then observed that the plants had fewer CBB symptoms and were growing normally.

The scientists proved that the methylation was stable in the presence of the transgene through clonal propagation. The findings provide evidence that DNA methylation can be used as a gene expression dial, an alternative to an on/off switch. It can also be used to create expression patterns in tissue- or environment-specific promoter, considering that DNA methylation does not change the DNA sequence. These suggest that DNA methylation may be useful in other crop improvement programs.

Read more in Nature Communications.