Comparison of cell wall components between Fragaria x ananassa and Fragaria chiloensis grown in Chile

Abstract

Fruit firmness and cell wall composition were compared among five cultivars of F.X ananassa ('Chandler', 'Seascape', 'Tudla', 'Hokowase' and 'Reiko') and two land races of F. chiloensis ('94BAU-1A' and '97PUR-1A') grown in central Chile. Fruits of F. chiloensis were smaller than those of F.X ananassa. Firmness of epidermal tissue did not differ significantly between F.X ananassa and F. chiloensis. Firmness of cortical tissue, however, was significantly lower in F. chiloensis than in F.X ananassa and as a result, difference in the firmness between epidermal and cortical tissues was significantly greater in F. chiloensis than in F.X ananassa. Calcium concentration was low in 'Reiko' and 'Hokowase' while high in the other varieties of F.X ananassa. F. chiloensis showed intermediate values between these two groups. Higher levels of total uronic acid and neutral sugars in cell wall fractions of F. chiloensis as compared with F.X ananassa were mainly due to its high concentration in the water soluble fraction. Total uronic acid in cell wall fraction was significantly higher in F. chiloensis than in F.X ananassa, mainly due to significantly higher concentrations in the water-soluble fraction. Non-cellulosic neutral sugars, especially arabinose in the water, CDTA, and Na2CO3-soluble fractions were significantly higher in F. chiloensis than in F.X ananassa. On the other hand, galactose in the CDTA-, Na2CO3-, and KOH-soluble fractions was significantly lower in F. chiloensis than in F.X ananassa. Moreover, cellulose concentration of F. chiloensis was also significantly lower than that of F.X ananassa. Results obtained from cell wall analysis suggest that softer cortex in F. chiloensis might be due to either lower cellulose content, higher solubilization rate of pectic substances, and/or compositional differences in the branching of neutral sugars.