Bx51 pd72 ix71

For histological observations, stalks from fruit samples that were collected 10 DAA were immediately stained in alkaline magenta solution and observed under a stereoscopic microscope at specific timepoints.
Non-pollinated, hand pollinated, and MT-treated fruit samples were collected at 5 DAA, immediately fixed in formalin-aceto-alcohol solution and stored at 4°C (Phillips and Hayman, 1970 (link)). The ovaries were dehydrated in an ethanol and xylene series, embedded in paraffin, sectioned into 8-μm slices, dried, and stained with safranine and fast green (Lin et al., 2007 (link)). Anatomical images were observed using a microscopic imaging system (BX51+PD72+IX71, OLYMPUS, Japan). Cell areas were ascertained from mesocarp longitudinal sections (30 cells per section from 10 to 15 sections) using ImageJ software.

The full-length CDS of GA20ox2 was cloned into a pCambia2300–green fluorescent protein (GFP) to form a translation fusion with the N-terminus of the GFP. The vector was kindly provided by Professor Xu Yan, Northwest A&F University. Agrobacterium tumefaciens strain EHA105, containing either a pCambia 2300 vector with 35S::GFP or the GA20ox2—35S::GA20ox2-GFP, was grown at 28°C in Luria–Bertani medium containing 50 mg L⁻¹ kanamycin and 25 mg L⁻¹ rifampicin. After 24 h, the Agrobacterium cells were harvested and resuspended in infiltration buffer [10 mM MgCl₂, 10 mM MES (pH 5.6) and 150 mM acetosyringone] to a final OD₆₀₀ of 0.8. The resuspended cells were shaken for 4 h at room temperature and then subjected to infiltration by a syringe. The methods of infection were based on Hellens et al. (2005) (link). The leaves were incubated in the dark at 22°C for 12 h and then placed in a growth chamber (25°C, 16-h/8-h day/night) for 4 to 5 days. Fluorescence Microscopic (BX51 + PD72 + IX71, OLYMPUS, Japan) imaging system was used to observe the anatomical images. Excitation and emission wavelengths were 498 nm and 516 nm respectively.

One cm-thick stem pieces of water-treated plants and GA₃-treated plants were collected at 30 and 90 DAT. Then, the 1 cm-thick stem pieces were immediately put into FAA solution (5 mL formalin, 5 mL acetic acid, 50 mL alcohol and 40 mL distilled water) and samples were stained with 1% safranin for 48 h. In accordance with Lv et al.’s method [60 (link)], a 10 μm-thick paraffin longitudinal section was obtained for observing axillary meristem formation under a microscope (BX51 + PD72 + IX71, OLYMPUS, Tokyo, Japan). At 120 and 150 DAT, axillary bud formation was checked in the control group and GA₃ treatment group by a stereoscopic fluorescence microscope (MZ10F, LEICA, Heidelberg, Germany).