Growth and development of tomato fruits in vivo and in vitro

Tomato (Lycopersicon esculentum Mill.) fruits of the male sterile cultivar Pearson (MS35 BC4, 61) were transferred to in vitro culture during the cell division period. Fruits grown in vivo and in vitro were compared throughout their development according to various growth parameters: fresh and dry weight, cell number, cell diameter, and DNA and total protein content. In all cases, the values pertaining to fruits grown in vitro were significantly lower than their in vivo counterparts. The final fresh weight of fruits transferred to culture 2, 5, or 10 days after pollination was only 0.7, 1.2, and 3.4%, respectively, of that of plant-grown fruits. The results indicate that the reduced fruit size in vitro is related to the reduction in both cell number and cell size. It is interesting to note that the DNA content per cell increased 15-fold during the growth of the plant-grown fruits while this accumulation was only between 2-and 3-fold in all the cultured fruits. The time to first colour appearance of fruits cultured 2, 5, or 10 days after pollination was 196, 132 and 85%, respectively, of that of plant-grown fruits.