Knockouts of Drought Sensitive Genes Improve Rice Grain Yield under both Drought and Well-Watered Field Conditions

Rice (Oryza sativa) is one of the most important staple food crops feeding more than half of the world’s population. One of the requirements for future sustainable rice production is to develop drought tolerant varieties. We have identified a number of drought sensitive tagged lines by screening our rice activation tagging population. Two of the sensitive lines, AH13391 and AH17392, exhibit reduced drought tolerance compared to the controls, and have a single T-DNA in a region next to an ATPase-associated with diverse cellular activities (AAA)-like gene, respectively. Constitutive overexpression of either AAA-like gene (OsAAA-1 and OsAAA-2) significantly reduced the drought tolerance, whereas knocking them out by CRISPR-Cas9 significantly increased grain yield under both drought and well-watered field conditions. Comparative analysis of different OsAAA-1-edited variations shows that the core AAA ATPase domain and the C-terminal end of OsAAA-1 protein are important for its function in drought sensitivity; and OsAAA genes may regulate drought sensitivity through interacting with other drought-stress responsive partners. Our results show that OsAAA genes play an important role in drought sensitivity and demonstrate the feasibility of improving drought tolerance by CRISPR-mediated knockouts of native rice drought sensitive genes.