Bioactive Gibberellins in Seeded and Seedless Grapes: Identification and Changes in Content During Berry Development

Abstract

GA₁ and precursors of the early 13-β-hydroxylation pathway of gibberellins biosynthesis GA₁₇ and GA₁₉ were identified in berries of seedless grape cv. Superior seedless by full-scan gas chromatography mass-spectrometry (GC-MS) and Kovats retention indices (KRI). GA₁, GA₁₇, GA₁₉, GA₃, and its decomposition product gibberellenic acid were also detected in the berries and seeds of Ribier, a seeded cultivar. Biologically active gibberellins were determined throughout fruit development by the α-amylase bioassay. Levels of active gibberellins expressed as equivalent of GA₃/g of fresh weight increased at the onset of the first berry growth phase, and at the initiation of the second growth-phase, in berries of both varieties, whereas in seeds maximum levels were attained during the lag phase. GA₃ equivalents were 77-fold higher in seeds compared to berries.