Rm2016

Multimode reader (Tecan, Switzerland, Spark 10M), Tissue Lyser (Spex, Geno 2010), Pathological slicing machine (Leica, RM2016), Microscope (Nikon, Eclipse Ci‐L), Automatic biochemical analyzer (Beckmancoulter, AU480), UHPLC (Agilent, 1290), Q‐TOF/MS (Agilent, 6538), Centrifugal thickener (Thermo Fisher, SPD131DDA‐PI‐230), and Fluorescence quantitative PCR (Stepone plus, ABI).

For light microscopy, the second leaf of the tea plant approximately 1 cm² in the middle were pre-fixed in formalin-aceto-alcohol (FAA) for 24 h, dehydrated with dehydrator (JJ-12 J, China), washed with xylene, and then paraffin-embedded using a histocentre embedding machine ( JB-P5, China). Next, samples were sectioned with a microtome (RM2016, China) at 5 μm thickness and stained with fast green and safranin for observation under a light microscope (Nikon Eclipse CI, Nikon DS-U3, Japan). The leaf ultrastructural changes in different samples were characterized by TEM. Briefly, small tea leaf blocks from the second leaf of the tea plant no more than 1 mm³ were successively fixed with 2.5% glutaraldehyde (pH 7.4) and 1% OsO4 (pH 7.4) at room temperature, followed by dehydration with an ascending gradient of ethanol-water and acetone-ethanol solutions, penetration and embedding by the resin EMBed 812. Next, the resin blocks were polymerized in an oven at 65 ℃, cut to 60–80 nm thin pieces on the ultramicrotome, placed on 150-mesh cuprum grids and stained by 2% uranium acetate and 2.6% lead citrate in sequence. Finally, the cuprum grids were observed and photographed under TEM (HT7800/HT7700, HITACHI, Japan).