Fig. 1 Amino acid sequence alignment of SARD1 proteins in Poncitrus trifoliata（Pt），Citrus sinensis（Cs） and Arabidopsis thaliana（At）

Fig. 2 Predication of phosphorylation sites（A）and N-glycosylation sites（B）in PtSARD1

Fig. 3 Subcellular localization analysis of PtSARD1 in Arabidopsis protoplast

Fig. 4 Expression patterns of PtSARD1 in different tissues（A）and in response to drought（B）as well as exogenous application of SA（C） Different lowercase letters indicate significant differences among various tested samples（P < 0.05）

Fig. 5 Generation（A）and identification（B）of PtSARD1-RNAi Poncirus trifoliata WT：Wild type；D-1 and D-2：PtSARD1-RNAi lines. The same below

Fig. 6 Morphological comparison（A）and relative water loss（B）of two PtSARD1-RNAi Poncirus trifoliata lines（D-1 and D-2）and the wild type（WT） *and ** indicate that there are significant differences at the levels of P < 0.05 and P < 0.01 between transgenetic plants and wild type. The same below

Fig. 7 Generation（A）and identification（B）of PtSARD1-overexpression tobacco lines WT：Wide type；EV：Empty vector；A7 and F7：PtSARD1-overexpression tobacco lines. The same below

Fig. 8 Morphological comparison（A）and relative water loss（B）of the wild type tobacco（WT） and two PtSARD1-overexpression tobacco lines（A7 and F7）

Fig. 9 Comparisons of morphology（A），proline content（B），electrolyte leakage（C）and malondialdehyde（MDA）content（D）in the wild type tobacco（WT）PtSARD1-overexpression tobacco lines（A7 and F7）under water withholding treatment Different lowercase letters indicate significant differences among the three lines at the same time point（P < 0.05）

Fig. 10 Salicylic acid contents of wild type tobacco and PtSARD1-overexpression tobacco lines（A7 and F7） Different lowercase letters indicate significant differences among different treatment time（P < 0.05）