'Chambourcin' grapevine (Vitis vinifera x Vitis L.) berries display sustained post-veraison accumulation of oxalic acid.

摘要

A substantial accumulation of organic acids (OA) occurs during pre-veraison grape berry development, which results in low pH and contributes to the sensory properties of fruits. The main OA in most grape berries are tartaric acid (TA) and malic acid (MA). MA is accumulated via a primary metabolic shunt, whereas TA is accumulated via ascorbic acid (AA; vitamin C) metabolism. Oxalic acid (OX) is also derived from AA in competition with TA, and results from a cleavage between the 2nd and 3rd C atoms. Oxalic acid is subsequently biomineralised as calcium oxalate crystals in idioblast cells. Biosynthesis of TA, MA and OX was determined during grape berry development in 4 grapevine cultivars. In the inter-specific hybrid, Chambourcin, there is a high capacity to accumulate OX during post-veraison fruit development. OX content increased from approx. 1 to 3 mg g--1 berry fresh wt. between 14 and 16 wk post-anthesis, resulting in OX levels that were similar to MA levels in mature fruits.