Crop Biotech Update

Scientists Use Cre-lox Gene Switch to Limit Bt Gene Expression in Green Tissues of Rice

November 15, 2017

Scientists from Zhejiang University and China National Rice Research Institute developed a modified Cre-lox gene switch to limit the expression of Bt protein in the green tissues of rice. They used two cassettes labeled as KEY and LOCK. KEY has a nuclear-localized Cre recombinase driven by the green-tissue-specific promoter rbcS; while LOCK has a Nos terminator (NosT), which is used to block the expression of the gene of interest (GOI), bounded by two loxP sites.

A complete gene switch system is in place when these two cassettes are pyramided into rice. The Cre recombinase from KEY cuts out loxP-NosT in LOCK and unlocks the GOI in green tissues but keeps it locked in the endosperm. This system was shown in eYFP and Bt expression assays. eYFP and Cre presence was confirmed in rice green plant parts including leaf, sheath, stem, and glume but not in the root, anther or seed of the gene-switch-controlled eYFP hybrids. Aside from the confined expression of the Bt protein in Bt hybrid rice, high resistance to striped stem borers and leaffolders was also observed.

Read the research article in Nature.