Total RNA Extraction and RT-qPCR Analysis

Total RNA was extracted from different tissues using pBIOZOL Plant Total RNA Extraction Reagent (BioFlux, Hangzhou, China) according to the protocol; then the extracted total RNA was treated with gDNA Eraser to remove genomic DNA as following the reaction system (5× g Eraser Buffer 2 μL, gDNA Eraser 1 μL, total RNA 1 µg) (Takara Bio, Dalian, China). Next, total RNA (1 µg) was reverse transcribed using the PrimeScriptTM RT kit (Takara Bio, Dalian, China) to obtain cDNA as following reaction system (PrimerScript RT Enzyme Mix I 1 μL, RT Primer Mix 1 μL, 5× PrimerScript Buffer 4 μL, total RNA 1 µg). The quantitative real-time PCR used an UltraSYBR Mixture (Low ROX) (CWBIO) with three biological replicates, and the detailed procedure referred to the manufacturer’s instructions. The RT-qPCR reaction was performed by qTOWER 3G Cycler (Analytik Jena, Germany) and the relative expression level analysis was calculated using 2^−△△CT method [36 (link),37 (link)]. We selected the UBQ7 gene as an internal reference gene [38 (link),39 (link)]. All PtrAPX specific primers for RT-qPCR and UBQ7 gene primers are listed in Supplementary Table S1.