The tissue-specific expression of barnase in tobacco delays axillary shoot development after topping.

Shoot branching is an important agronomic trait that determines plant architecture and affects crop productivity (Shen et al., 2019). Molecular signals from the shoot apical meristem (SAM) create a hormonal environment that integrates with the expression of axillary bud-specific repressors such as BRANCHED1 (BRC1) to inhibit axillary shoot formation (Wang et al., 2019 and references therein). The signal is eliminated by topping (SAM removal), enabling the formation of new shoots (suckers) from axillary buds (Figure 1a).