Comparative analysis of the stellacyanins (SCs) family and focus on drought resistance of PtSC18 in Populus trichocarpa

•A total of 74 SCs from poplar and other four species were identified and analyzed.•A key candidate gene PtSC18 that strongly responded to drought stress was screened.•Overexpression of PtSC18 enhanced drought tolerance of transgenic Arabidopsis by improving water retention and reducing oxidative damage.