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. 2020 Jul 17;184(1):194–211. doi: 10.1104/pp.20.00476

Figure 8.

Figure 8.

The effect of MsSCL26.1 on the transcription of genes encoding ROS scavenging system-related enzymes. A, Qualitative and quantitative evaluation of MsSCL26.1-mediated activation of antioxidant enzyme genes in a dual LUC reporter system. The data are presented as means ± sd from three biological replicates. Asterisks indicate significant differences between treatments and controls based on Duncan’s multiple range test (*P < 0.05). Scale bar = 1 cm. B to E, Transient expression assays of MDHAR promoter activity modulated by MsSCL26.1 in N. benthamiana leaves. B, Effector and reporter vectors used in the transient expression system. C, GUS staining of N. benthamiana leaves from the transient expression assays. D and E, Relative GUS activity (GUS/LUC) and quantitative analysis of GUS activity from coinjected N. benthamiana leaves. F, MDHAR activity and AsA content in transgenic and nontransgenic apple plants subjected to salt and osmotic stress in vitro for 10 d. The data are presented as means ± sd from three biological replicates. Asterisks indicate significant differences between treatments and controls based on Duncan’s multiple range test (*P < 0.05). G, Model of the mdm-miR171i-MsSCL26.1-mediated drought-stress–responsive network in apple. Antioxidants, such as AsA, are oxidized to MDHA under drought stress, which is accompanied by the release of a large number of ROS. The accumulation of high levels of ROS and other oxidation products, such as MDHA, seriously threaten the survival of the plant. Meanwhile, the transcript level of mdm-miR171i is significantly inhibited by drought stress, which reduces the repression of MsSCL26.1 in plants, especially in the roots, and might partly contribute to the upregulation of MsSCL26.1. MsSCL26.1 activates the expression of antioxidant enzyme genes, such as MsMDHAR. MsMDHAR catalyzes the reduction of MDHA into AsA, thus maintaining the homeostasis of AsA metabolism in plant cells under drought stress. Arrows, positive relationship; T-bar, negative (inhibitory) relationship.