Onset and progression of the berry shrivel ripening disorder in grapes

摘要

Background and Aims The grape ripening disorder called berry shrivel is characterised by cessation of sugar accumulation, low pH, impaired anthocyanin biosynthesis in dark-skinned cultivars and water loss. We tested whether damage to the bunch peduncle vasculature can induce berry shrivel and whether cell death in the rachis precedes cell death in the berries.Methods and Results Peduncle phloem removal, but not xylem removal, resulted in symptoms resembling berry shrivel. Fluorescein diacetate staining, however, and microscopic observations of non-manipulated bunches showed that cell death in the berries often preceded that in the rachis. Mesocarp cell death started around the central vasculature proximal to the seeds and spread outward as symptoms worsened. Berries near the bunch tip were the earliest to be affected and developed the most severe symptoms, but ripening of all berries on symptomatic bunches was impaired.Conclusions Loss of functionality of the rachis phloem may not be the primary cause of berry shrivel. The disorder may originate in the distal berries of a bunch and spread towards the proximal berries as they soften at the onset of ripening.Significance of the Study This study contributes towards an eventual understanding of the causes and consequences of an important grape ripening disorder.