Arrested Sugar Accumulation and Altered Organic Acid Metabolism in Grape Berries Affected by Berry Shrivel Syndrome

Abstract

Berry samples were collected over four growing seasons from field-grown Cabernet Sauvignon grapevines in the Columbia Valley of southeastern Washington. Shoots were tagged prior to veraison and berries were sampled weekly from the same clusters. Symptoms of berry shrivel (BS) and bunch-stem necrosis (BSN) were monitored through harvest and berry samples were categorized as “healthy,” BS, or BSN for analysis of sugars, organic acids, potassium, and calcium. The vines of four adjacent rows were geolocated using GPS over three years to determine if BS was associated with specific vines or specific locations within the vineyard. Like BSN, the BS syndrome was seemingly restricted to individual clusters rather than individual vines and was spatially unpredictable from year to year. Vines propagated from BS-afflicted shoots only rarely displayed BS symptoms. Ripening-associated changes in berry solutes began simultaneously in healthy and BS clusters at veraison, but accumulation of sugars, K⁺, and oxalate ceased before shriveling symptoms became apparent on BS clusters. While BS did not affect tartrate, it was associated with slightly faster malate catabolism and slower decrease in soluble Ca²⁺ than in healthy berries. BS was not only associated with a cessation of phloem inflow into the berries, but also with altered organic acid metabolism and metal cation use.