Figure 1.

Effect of enhanced cytokinin biosynthesis on the photosynthetic activity response to partial defoliation. Photosynthetic rate (A), stomatal conductance (B), and rate of photosynthesis per internal CO₂ concentration (Ci; C) of source leaves in nondefoliated plants (hatched bars) and remaining tomato leaves after partial defoliation of the other leaves (empty bars). Defoliation was performed on mature plants at the reproductive stage of variety M82 and transgenic tomato plants expressing IPT under FBPase (FBPase:IPT, plant line #2) or AtMDK (MDK:IPT, plant line #5) promoters. Plants were grown in a temperature-controlled greenhouse (25°C/18°C day/night). Data represent means (±SE) of six biological replicates. Different letters indicate significant differences between the tomato lines on a specific date (p < 0.05) by Tukey HSD test. Asterisks indicate significant differences between partially defoliated and nondefoliated same tomato line at p < 0.05 by Student’s t-test.