ACL1-HD-Zip IV complex revealed common mechanism in rice response to brown planthopper and drought. Being a small peptide, ACL1 might function through forming complex with other proteins. So that we searched the possible interacting proteins of ACL1 using the TurboID system.

Brown planthopper (BPH) is the most notorious insect pest to rice. Drought is the most commonly occurring global adversity. BPH infestation caused adaxially-rolled leaves and shrunk bulliform cells similar to drought. The bulliform-cell characteristic gene, ACL1, negatively regulated BPH resistance and drought tolerance, with decreased cuticular wax in ACL1-D, which resulted in quicker water losing. ACL1 was specifically expressed in epidermis. TurboID system and various biochemical assays revealed that ACL1 interacted with the epidermal-characteristic HD-Zip IV ROCs. ROC4 and ROC5 positively regulated BPH resistance and drought tolerance through modulating cuticular wax and bulliform cells respectively. Overexpression of ROC4 and ROC5 both rescued ACL1-D in various related phenotypes simultaneously. Moreover, ACL1 competed with ROC4 and ROC5 in homo-dimerization and hetero-dimerization. Altogether, we illustrated that ACL1-ROCs complex synergistically mediate drought tolerance and BPH resistance through regulating cuticular wax and bulliform cells in rice, a new mechanism which might facilitate BPH resistance breeding.