A major bottleneck in genome editing of many perennial plants is their recalcitrance to transformation and regeneration. To boost genome editing in such perennial crops, transcriptional reprogramming of morphogenic genes is introduced by CRISPR-Combo, a versatile system for simultaneous genome editing and transcriptional activation in plant cells. In potato, we screen 17 morphogenic genes and identify 4 genes (WOX11/12, ARF5, ABI3-1, and ABI3-2) that promote regeneration of genome-edited hairy roots, and 3 of the 4 genes are also found to boost shoot regeneration by Agrobacterium-mediated stable transformation. Similarly, screening of 10 morphogenic genes in citrus leads to the identification of 5 genes (BBM3, FUS3, IPT1, SERK1, and STM) that enhance plant regeneration upon activation. In wild strawberry, we demonstrate that simultaneous activation of Baby Boom genes (BBM1 and BBM2) or of GRF3 and GIF1 reduces the generation time of genome-edited plants by over one month. Moreover, in poplar, we show that simultaneous activation of WUS and WOX11 synergistically promotes plant regeneration without exogenous plant hormones, which leads to a protocol of generating genome-edited poplar shoots in less than one month. Collectively, this study provides efficient strategies for boosting genome editing in four perennial crops. Perennial plants are often difficult to improve genetically because they are hard to transform and regenerate. Here, the authors used CRISPR-Combo-mediated activation of morphogenic genes to accelerate genome editing and plant recovery in potato, citrus, strawberry, and poplar.
Ramasamy et al. (Wed,) studied this question.