Ethanol

Tea leaves were sliced (1 cm × 1 cm) and soaked in a glutaraldehyde-fixed solution (Beijing Solarbio Science & Technology Co., Ltd., Beijing, China) overnight. After gradient dehydration with 30%, 50%, 70%, and 90% ethanol (Sangon Biotech (Shanghai) Co., Ltd., Shanghai, China), followed by freeze drying and gold spraying, an S-3400N scanning electron microscope (Hitachi Limited Co., Ltd., Tokyo, Japan) was used to observe tea leaf cuticular wax.

Zinc acetate (Zn(CH₃COO)₂·2H₂O), sodium citrate (Na₃C₆H₅O₇·2H₂O), sodium hydroxide (NaOH), and ethanol (AR) were purchased from Sangon Biotech (China, www.sangon.com). ZnO was synthesized by a simple one-step method. A total of 0.2195 g of zinc acetate and 0.2941 g of sodium citrate were dissolved in 40 mL of deionized water and magnetically stirred for 10 min to form a clear solution. The above mixed solution was used as a precursor solution. Then, a certain amount of 3 mol/L NaOH solution was added dropwise to the precursor solution, and the PH values of the solutions were adjusted to be 9, 10 and 11. The above mixed solution was transferred to a 100 mL autoclave, sealed, and placed in a constant temperature drying oven at 120 °C for 8 h. It was cooled to room temperature, washed several times with deionized water and absolute ethanol, and placed in a constant temperature drying oven at 60 °C to be dried. We named the samples synthesized under the above three different PH values ZnO-1, ZnO-2, and ZnO-3.

The chemicals used in the experiments before the digestion (calcium chloride and ethanol) were purchased from Sangon Biotech Co. Ltd, Shanghai, China. Chymotrypsin was supplied by Thermo Fisher Scientific. MeOH and FA were purchased from Sigma—Aldrich (St. Louis, MO).

The new vegetable tanned cattle leather was collected from the market (Houjie Dingtai Leather Company, Dongguan, China).
The required reagents for the artificial aging experiments include hydrochloric acid (HCl), ammonium bicarbonate (NH₄HCO₃), and sodium hydroxide (NaOH). All reagents are of analytical grade and were obtained from Sangon Biotech (Shanghai, China) Co., Ltd.
For the orthogonal experiments, the following reagents were used: NaOH (analytical grade, Sangon Biotech) and a protein concentration determination kit (Sangon Biotech).
The reagents used for electrophoresis experiments include precast gels, protein loading buffer, electrophoresis running buffer, protein maker, ethanol, methanol, acetic acid, ammonium sulfate, and Coomassie brilliant blue G250. All reagents are of analytical grade and were purchased from Sangon Biotech.
For the biomass spectrometry experiments, the required reagents include formic acid (chromatography grade, Sigma, St. Louis, MO, USA), acetonitrile (chromatography grade, Sigma), and trypsin (sequencing grade, Promega, Madison, WI, USA).
All reagents used in these experiments are of high purity and were procured from reputable suppliers. The quality of the reagents ensures the reliability and accuracy of the experimental results.

For total RNA isolation, Trizol (Invitrogen, Carlsbad, CA, USA), chloroform (China sinopharm, Shanghai, China) and isopropanol (Sangon biotech, Shanghai, China) were added into irradiated cells, subsequently followed by 75% ethanol (China sinopharm) rinsing. The reverse transcription reaction system was performed according to the manufacturer’s protocol of the PrimeScript RT Master Mix kit (Takara, Tokyo, Japan). The synthesized cDNA samples were amplified and detected in the RT-qPCR system under the instruction of TB Green Premix Ex Taq II kit (Takara) in QuantStudio 6 (Thermo) (Tables S1–S5, RT-qPCR protocol).