The Role of Leaf as Affected by Phyllotaxis and Leaf Histology on the Development of the Fruit in Tomato

The role of leaf as affected by phyllotaxis and leaf histology on development of individual fruit on an inflorescence and fruit development as a whole were investigated by the transport and distribution patterns of 14C-assimilates in tomato.Tomato plants have alternate with four orthostichies with divergence of 90° (270°) and 180°, and floral axes of raceme situate on one orthostichy. The 1st and 3rd fruit was situated on one side of the peduncle, and the 2nd and 4th fruit was situated on the opposite side of the peduncle.The percentage of distribution of 14C-assimilates and RSS (Relative strength as a sink) to the 1st and 3rd fruit of an inflorescence were higher than those of 2nd and 4th fruit from the leaf which was situated just below the inflorescence and on the same side to the 1st and 3rd fruit.Furthermore, the distribution pattern indicated that the leaf just above the inflorescence exports 14C-assimilates to the fruit on the inflorescence as well as the leaf below the inflorescence but located on the opposite side to the inflorescence.The distribution pattern from the leaf on a lateral branch indicated that the inflorescence of the main axis still act as a large sink. However, the RSS values for the leaf on a lateral branch revealed that the inflorescence on the lateral branch was a stronger sink than that on main axis. Since fruit developing stages differ in those inflorescences, fruit size and weight should be different, which heavily contribute to the percentage of distribution to each inflorescence. Therefore, it sometimes happens that the percentage of distribution and the RSS value do not always go together.From these results, the accumulation of 14C-assimilates to an inflorescence is likely affected by their proximity to the source leaf, their developmental stage and the connection of vascular system in the stem.