VARIETAL DIFFERENCES AND CHANGES IN CELL- WALL COMPOSITION IN RIPENING FIG FRUITS

To elucidate the varietal differences in cell wall composition of fig fruits at harvest, the uronic acid and neutral sugar contents in the s yconia of Caprifig 'VC-180' (Ficus carica L. var. intermedia Shinn x F . carica L. var. sylvestris Shinn), San Pedro type 'King' and 'San Ped ro White' (F. carica L. var. intermedia Shinn) and common figs 'Masui Dauphine' and 'Houraishi' (F. carica L. var. hortensis Shinn) were ana lyzed. In addition, the changes in cell wall composition of ripening ' Masui Dauphine' fruits were investigated, comparing uronic acid and ne utral sugar contents in the syconia exhibiting 10, 50, and 100% colore d peel. Cell wall polysaccharides were sequentially extracted from eth anol insoluble materials of pistillate flowers with water, hot-water, EDTA, KOH (hemicellulose fraction), and H2SO4 (cellulose fraction) sol utions. 1. In the water fractions, the varietal difference in cell wal l composition was very small. The total sugar contents, including uron ic acid and neutral sugar, in the hot-water, EDTA, hemicellulose, and cellulose fractions were significantly highest in the syconia of 'VC-1 80'. Except for 'VC-180', the difference in neutral sugar contents in the cellulose fractions was largest among other cultivars. 2. The uron ic acid contents per unit weight in the water fractions, extracted fro m 'Masui Dauphine' syconia during ripening, became higher in the order of 50, 100, and 10% colored peel, but there was little difference in the neutral sugar contents in the same fractions. In the hot-water and EDTA fractions, the uronic acid contents per unit weight decreased wi th color development; therefore, the total sugar contents from pectic substances likewise decreased. In the hemicellulose and cellulose frac tions, both the uronic acid and neutral sugar contents per unit weight decreased with color development. 3. The cell wall composition per fr uit of 'Masui Dauphine' was different from that per unit weight, becau se the ripening fruits increased in weight. As the percentage of color ing in the peel increased, the uronic acid contents per fruit increase d markedly in the water fractions and decreased in the hot-water and E DTA fractions;the neutral sugar contents per fruit increased in the wa ter and hot-water fractions. However, there were no differences in the total sugars per fruit derived from the pectic substances or in the u ronic acid, neutral sugar, and total sugars per fruit derived from the hemicellulose and cellulose fractions during the ripening process.