Gibberellin-Treated Seedless Cultivation Alters Berry Fracture Behavior, Cell Size and Cell Wall Components in the Interspecific Hybrid Table Grape (Vitis labruscana × Vitis vinifera) ‘Shine Muscat’

TL;DR

Gibberellin treatment in seedless grape cultivation changes berry texture, cell size, and cell wall composition during development.

Contribution

This study identifies how and when gibberellin treatment alters cell and cell wall features affecting berry texture in ‘Shine Muscat’ grapes.

Findings

GA-treated berries had higher fracture load and lower strain but similar toughness compared to non-treated berries.

GA treatment increased cell size heterogeneity and radial expansion in mesocarp tissues.

GA altered cell wall pectin content and gene expression related to cell expansion and pectin modification.

Abstract

Gibberellin (GA)-based seedless cultivation is widely used in the skin-edible interspecific table grape (Vitis labruscana × Vitis vinifera) ‘Shine Muscat’, yet when and how GA treatment reshapes fracture-type texture during berry development remains unclear. This study aimed to identify developmental stages and tissue/cell-wall features associated with GA-dependent differences in berry fracture behavior. We integrated intact-berry fracture testing at harvest (DAFB105), quantitative histology of pericarp/mesocarp tissues just before veraison (DAFB39) and at harvest, sequential cell-wall fractionation assays targeting pectin-rich (uronic acid) and hemicellulose/cellulose-related pools at cell division period, cell expansion period and harvest, and stage-resolved RNA-Seq across the same three developmental stages. GA-treated berries had a larger diameter and showed a higher fracture load and a lower fracture strain than non-treated berries at harvest, while toughness did not differ significantly. Histology revealed thicker pericarp tissues and lower mesocarp cell density in GA-treated berries, together with increased cell-size heterogeneity and enhanced radial cell expansion. Cell wall analyses showed stage-dependent decreases in uronic acid contents in water-, EDTA-, and Na2CO3-soluble fractions in GA-treated berries. Transcriptome profiling indicated GA-responsive expression of putative cell expansion/primary-wall remodeling genes, EXORDIUM and xyloglucan endotransglucosylase/hydrolases, at DAFB24 and suggested relatively enhanced ethylene-/senescence-associated transcriptional programs together with pectin-modifying related genes, Polygaracturonase/pectate lyase and pectin methylesterase, in non-treated mature berries. Collectively, GA treatment modifies mesocarp cellular architecture and pectin-centered wall status in a stage-dependent manner, providing a tissue- and cell wall–based framework for interpreting fracture-related texture differences under GA-based seedless cultivation in ‘Shine Muscat’.

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