*2.9. Determination of Antioxidant Enzyme Activities*

The supernatant attained from total soluble sugar was supplementarily used to determine the activities of antioxidants. Three replications were used to determine these antioxidant activities. To observe the SOD activity, the protocol utilized by Giannopolitis and Ries [41] was pursued with minor modifications. In addition, the SOD activity was estimated as U g−<sup>1</sup> FW. Activity of catalase was estimated following the approach of Aebi [42]. The peroxidase (POD) activity was assessed by following Change and Maehly [43] detailed protocol. The enzyme activity (APX, POD, CAT) was deliberated as μ mol min−<sup>1</sup> mg−<sup>1</sup> protein at 25 ± 2 ◦C [44].

#### *2.10. Analysis of Gene Expression*

The transcript levels of SA-related genes were estimated by qRT-PCR. In a mortar and pestle, thawed shoot samples of both rice cultivars were crushed inside liquid nitrogen. Trizol method was used to extract the RNA, as already defined [45]. The NanoDrop 2000/2000 c (Thermo-Fisher Scientific, Waltham, MA, USA) was used to identify the purity of RNA. Subsequently, the synthesis of cDNA was accomplished by PrimeScript™ RT reagent kit. Three replications were used to analyze the gene expression level. The *PR1*, *PR2*, and *NPR1* gene primers were utilized to analyze the concerned gene expressions. The used primers are listed in Supplementary Table S1. The 2XSYBR Green Master Mix reagent (10 μL volume), (Applied Biosystems, Foster City, CA, USA), 200 nM gene-specific primers, and cDNA samples (6 μL volume) were utilized to prepare the 20 μL reaction mixture. The relative alteration inside the expression of genes was identified as documented [46]. The

house-keeping gene (*OsActin*) was utilized as a control gene to standardize the other genes during internal calibration.
