CRISPR/Cas9-Based Co-editing of KUP9 and CIPK9 Genes in Rapeseed (Brassica napus) to Improve Drought Tolerance and Yield Traits

Abstract

Drought stress restricts rapeseed yield. KUP9 is involved in potassium ion transport and osmotic regulation whereas CIPK9 mediates abscisic acid signaling and stomatal movement which form an interaction network through potassium homeostasis and signal transduction. A dual-gene tandem expression cassette vector based on CRISPR/Cas9 was designed, optimization of genetic transformation and screening strategies were performed, and we obtained plants co-edited for KUP9 and CIPK9 showing enhanced root potassium uptake, synergistically accumulating proline and soluble sugars, and preferential allocation of photosynthates into seeds; yield components showed a non-antagonistic relationship with drought-tolerance physiological indicators, and its yield loss under moderate drought was decreased by about 30%, and this co-editing strategy decouples the negative correlation between drought tolerance and yield.