Inhibition of eukaryotic galactolipid biosynthesis in mature-green tomato fruits at chilling temperature

Abstract

This research aimed at clarifying the relationship between the impairment of galactolipid biosynthesis at low temperature and chilling-sensitivity of tomato fruits. Molecular species of galactolipids were analyzed in mature-green pericarp of tolerant ‘New York 280’ (‘NY’) and sensitive ‘Early Cherry’ (‘EC’) before and after 16 days of chilling, and compared with unchilled pink fruits, undergoing normal ripening, used as controls. Total galactolipid content changed little during ripening, but decreased markedly at 4°C. The ratio of di- to monogalactosyl-diacylglycerol ( DGDG MGDG ) was higher in ‘NY’ than in ‘EC’ at the mature-green stage. The ratio increased during ripening in both cultivars, particularly in ‘EC’, and reached the same level in ‘EC’ as in ‘NY’ at the pink stage. At 4°C the ratio did not increase in ‘EC’. Eukaryotic MGDG increased from about 80% to 95% in the two cultivars during ripening. By contrast, during chilling the % of MGDG eukaryotic species increased slowly to 87% in ‘NY’ while it decreased to 67% in ‘EC’. Condensation of MGDG to DGDG increasingly selected prokaryotic species during ripening, but this condensation of prokaryotic species to DGDG was inhibited in ‘EC’ at 4°C. The data indicate that the reduced galactolipid content in mature-green tomato pericarp after chilling resulted from the inhibition of eukaryotic galactolipid biosynthesis.